# New PM-25MV Mill



## shooter123456

After getting some Christmas money and making a few extra bucks with a machining job, I decided to get a new milling machine.  I currently have a Harbor Freight X2 that I have had for a little over 2 years now.  I will be converting the PM-25 to CNC immediately.  I intend for this thread to be similar to my PM1030v thread where I try to share details about the machine that I didn't find before buying it, get help with things that aren't quite right, and share what I find the machine is capable of. 

I currently have all the CNC components from my X2 and they should be sufficient for the PM-25, except the X axis ball screw which will only allow for 17 inches instead of the full 20.  That will be replaced relatively soon.

It will be converted and upgraded in 3 stages.
1. CNC Retrofit
     -400 oz-in steppers on each axis
     -1605 single nut ballscrews
     -TB6600 drivers
     -Control with LinuxCNC

2. Automatic Tool Changer + Spindle speed increase
     -10 Tool Umbrella Changer
     -Pneumatic Cylinder
     -TTS Style Holders
     -Angular Contact bearings in the spindle
     -New Pulleys

3. Full Enclosure similar to Tormach 440

A few reasons I chose this mill specifically:
     1. PM customer support and 3 year warranty.  After my experience with the lathe, their quick responses (The longest it ever took to get a reply was 12 minutes), and their quick shipping of parts covered under warranty. 
     2. Most parts from my X2 can be reused for the CNC, then I can revert the X2 to manual.
     3. Size.  My shop is currently a 2 car garage that needs to be able to get a car in if necessary.  Right now I have 2 lathes, a mill, a grinder, a work bench, drill press, and band saw in there and it is getting full. 
     4. Belt Drive.  I was also considering the G0704 and PM-727.  I didn't want to have to deal with making a belt drive for the spindle or taking apart the head to get the gears out.
     5. 120V power.  I was considering the PM-30MV because it has a 2 HP motor instead of 1, has a few extra inches of travel in each direction, and weights nearly double what the PM-25 weighs. But with 220v power and a breaker box that is full, I would need to hire an electrician to either put in another breaker box or rewire it somehow to make space.  With the cost of the rewiring, the need to buy all new CNC components, and the extra cost of the mill, it got pushed too far out of my budget. 

The machine shipped yesterday and I got the call this morning that it will be delivered this afternoon.  If the truck arrives before 4:06 PM, it will have shipped from PA to NC in less than 24 hours.  I elected for the lift gate delivery this time since I no longer have access to a truck and a trailer.  

I have plans for some extras for this machine that I think will be fun.
     1. 4th axis, either a trunion table or just a chuck.
     2. New spindle for a BT-25ish tool or something entirely custom.
     3. Servos (maybe)
     4. A touch probe
     5. Flood coolant
     6. A control panel

Right now, the delivery is scheduled for between 4pm and 6pm, with the estimated arrival time of 4:26 to 4:35.  I will post pictures and more details this evening when it gets here.


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## 7milesup

Sweet!   Will be watching your thread.  

I have been thinking about converting my 833T to CNC, but the finance department would become significantly cranky(er)...


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## tweinke

Will be watching this, learned a lot from your 1030v thread.


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## shooter123456

The machine was delivered yesterday without any issues.  I was going to upload pictures last night but imgur was having server issues.  I will have to keep it brief, but I will add more details later. 

The driver had a 48' trailer that managed to turn around in a cul de sac.  If you have never seen that, it is really impressive.  Hats off to that guy managing to get into a residential street, unload the machine and drop it in the garage, and get the truck turned around in about 10 minutes.  

The machine was crated well and arrived without any damage. Here is a picture of the crate on the pallet. 




With the crate taken apart.  Everything looking good.



I had to take the table and head off in order to lift it onto the bench.  No engine hoist and no one to help lift.  While I was taking the head off, I got a picture of the underside of the base casting.  Its a much higher quality casting than the X2 I have.  You can also see the Y axis leadscrew in there with the brass nut.  The machine has 20mm leadscrews. 



I took the table off which wasn't difficult.  It slid along very smoothly and popped right off at the end of travel. I weighed the table at 66.7 lbs with leadscrew.  The head weighed in at 56.9 lbs.  I gotta say, the bottom of that table is gorgeous.  The ways are ground and you can only see faint traces of machining marks in a few places.  The rest is ground completely smooth.  The leadscrew is also 20mm and is about 30 inches long.  Table travel without overshooting the ways is 20.5".



If the machine weight of 265 is correct, that means column, base, and saddle weigh in around 140 lbs.  It was heavy so I didn't want to put it down on the scale once I picked it up.  I just lifted and placed it up on the bench.  Those parts along weighed more than my entire X2.  Definitely a beefy machine and a large step up.  Right now it is on a fish tank stand I built.  It supported a 30 gallon tank for 2 years so I know it can handle the weight, but it will ultimately be replaced by a dedicated stand. 



It has oil channels machined into the ways which should make it easier to prevent the machine from binding.  You can see the holes for attaching the X axis nut, and the hole in the fire side way is for attaching the Y axis leadscrew.  With that position, it loses about an inch of travel on the far end, and it has to over travel the ways by about 1.5" to get the full 7" of travel.  The Y axis also slid nicely without any binding.



The base dovetails look fantastic as well.  Definitely ground all around.  That grease looking stuff on the ways felt like some kind of glue.  It didn't come up with acetone or isopropyl alcohol, so I am not sure how to get it up.  I am not sure what those markings in the top ground surface are.  You couldn't feel anything raised or depressed there, so its either a casting defect or light scratch. 



The head went back on without any issues.  I placed it on its side on a block of wood, then just positioned the Z axis saddle and pushed it into place.  The Z axis slid well, but it is exhausting turning that handle to lift the head and lower it.  The chip guard is attached to a switch so if the guard is open, it won't start.  But that cover immediately hit the vise when I tried doing some test cuts.  So the whole thing was removed and luckily the switch defaults to on, so if you pop the bar out, its fine.  



Test cuts went pretty well.  It machined nicely and the motor was able to put out decent torque.  I didn't push it too hard but it chewed up some aluminum for a few minutes.  The motor speed fluctuates a little while I was turning handles, but usually kept within about 30 RPM.  I didn't cut much, I just wanted to make sure everything would work before going ahead with CNC.  I need to learn how to adjust the gibs correctly because there were a few points where it started to chatter a bit inexplicably with heavier cuts, but I was satisfied with its performance.



The motor is a 2500 RPM motor and the high speed is a 1:1 drive.  I had asked PM beforehand what the RPM of the motor was and they said they think it is 5000 but they are not sure.  I don't think there is going to be room to get a 2:1 belt drive to get the spindle up to 5000, unless I make a new motor mount.  That isn't a big deal though.  If it was, I would have asked to know for sure before I bought it.  The motor also makes a bit of a clicking sound as it rotates.  Im not sure if that is normal.  It is quieter than my brushed motors except for that clicking.  I haven't measured spindle runout yet.  In the electronics box, the power button wasn't installed all the way so it was loose.  I popped it all the way in and that was fine.  I tried to figure out who makes the motor and controller to get some specs on them, but neither had any markings that I could find.  The spindle is controlled by a potentiometer, so I think I can swap that for an electronic pot to control it. I also noticed the E-stop button was significantly lower quality than the E-stop on my lathe.  The lathe e-stop, you just twist to release and it pops out. On this one, it doesn't feel spring loaded so you do all the twisting to get it to release.  It just doesn't feel as nice or as solid as the lathe e-stop.  It also feels like much cheaper and flimsier plastic. I am also not a huge fan of where that is positioned.  On the X2, it was positioned on the right side of the box and on the lathe it is right on top.  This one is kind of tucked in a corner and partially obstructed by the mounting for the chip guard.  When something is going wrong to the point that you are reaching for the EMERGENCY stop, and not the regular stop, I want it to be unobscured and easy to get to. 

A few perks though that I wasn't expecting: The toolbox is a much nicer one than came with the lathe.  It is plastic with a nice handle on top and a clear top compartment.  The lathe came with a sheet metal one that is fine for what it is, just not as nice.  The oiler is also way nicer. The one that came with the lathe leaked more oil than it dispensed and the nose didn't fit into the oilers.  This one is a plastic squeeze bottle type and the nose fights right into the oil holes.  It didn't leak at all when I used it.  



There is also a drain with a hose attachment on the table for draining flood coolant.  There is a machined recess at the top that is at a slight slant so it will drain out.  I thought that was a nice touch and I wasn't expecting it.  The table also had a t-slot at the front that had stops installed. The T slot would have been useful for installing a DRO if this machine was going to have one.  They also used some kind of sticky yellow glue to protect the table, instead of a grease.  It took a bunch of acetone to get it off and I haven't gotten all of it off yet.  



I may be needing new ballscrews immediately.  My X ballscrew is 550mm (21.5 inch) vs the 30" leadscrew.  That may leave me losing more travel than I thought.  The Y axis ballscrew is 11.9" and the leadscrew is about 13, so that one might be ok.  

I have AC bearings ready for each axis and I think they will be sufficient.  I think I will end up upgrading the Z axis pretty quick with a 20mm screw and Nema 34, so I will need new AC bearings.  I will have to figure out how to preload these bearings right as well.


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## shooter123456

How to remove the Z axis leadscrew on a PM-25MV mill.  (I couldn't find it by googling, so hopefully the next guy can find this)

It took me a while to get the Z axis leadscrew out because of the way the miter gears are installed.  Turns out, you need to remove it all in a pretty specific order. 

Step 1. Lock the Z axis gibs so the head stays in place.  It might be a good idea to put a note or mark somewhere so you don't forget the leadscrew is out, then unlock the gibs and have the head fall. 

Step 2. Remove the column cap.



Step 3. Remove the lock nut from the Z axis lead screw while holding the Z axis handle to keep it in place.



Step 4. Remove the set screw holding the smaller miter gear to the shaft.



Step 5. Tap the shaft out from right to left.  The Z axis handle will come out with it. 



This is what that shaft looks like with the handle removed, but it does not have to be.



Step 6. Remove the large miter gear from the Z axis lead screw. 



Step 7. Remove the key in the Z axis lead screw.  If you try to drive it out before removing the key, you will break a thrust bearing.  This is what the shaft looks like.



Step 8. Remove the screw from the Z axis saddle that holds the lead nut in place. 



Step 9. Jiggle the lead screw until you get it to drop free, while holding the nut so you can lower it down.

Step 10.  Once the leadscrew is free, remove the 4 screws holding the handle plate in place.  Then pull straight out. There are roll pins in place so it can only be pulled straight out.



Step 11. While holding the nut from the front of the column, unscrew the leadscrew until it is free of the nut.  Pull the screw out and then pull the nut out.

Step 12. Nap time, cuz that was exhausting.


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## shooter123456

I have had the chance to play with the mill a bit more and get started on the CNC parts.  I forgot just how much fun it was turning handles and how fast simple operations can be.  

I modeled up the conversion parts I will be using.  I am going to need to make 15 total parts.  I am currently shopping for a new X axis ballscrew with double nuts and a nema 34 for the Z axis.



The machine is very capable and leaves a very nice finish in aluminum.  It has been able to hold .001" without much effort on my part.  If I tried a little harder, it would certainly do better. 



A couple of weird things I have experienced so far:
1. When I lock the X axis gibs, the Y axis tightens up and becomes harder to turn.  The only thing I can think of that would cause that is the saddle distorting when the gibs are tightened.
2. There is a point on the X axis where it starts chattering a bit in deep cuts.  It is only about half an inch that it happens so I figure it must be something with the leadscrew, or maybe a low spot in the ways.
3. There is a slight delay from the spindle motor when you start a cut.  When the cut starts, it pauses for maybe half a second while the RPMs drop, then it jacks up the torque and gets the spindle back up to speed.  It takes way longer for this motor to respond than the brushed motors I have used.


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## shooter123456

Motors are mounted and axes are moving.  Looks like my careful measuring at the beginning paid off because every part went on without an issue and the machine moves smoothly.

Here is the Y axis motor mount.  The ballscrew I have on the Y is about an inch too short so I am down to 6" of travel.  When the funds allow, that will be replaced with a longer double nut screw.



Here is the X axis mount.  The picture isn't very good because the lighting is bad.  I need to get some more light over in that corner of the garage.  The X axis loses 5" travel with the current ballscrew.  This one will also be replaced with a longer double nut screw when the funds allow for it.



Here is the Z axis.  This unfortunately isn't going to last as long as I hoped it would.  The 400 oz in motor didn't have the torque to reliably move the head.  The motor would not lift the head under 60 IPM or over 120.  At 50 IPM, it would try to move it, maybe make a quarter of an inch, then the head would fall as the motor strained.  At 75 IPM, it would move the head well, but would stall roughly 10% of the time when it was lifted.  I am looking at Nema 34 motors and drives now to replace it.  I think I will make a simple adapter plate to allow the Nema 34 to mount to the Nema 23 mount.  I am thinking somewhere in the 900-1200 oz in range.  Since there will be a pneumatic cylinder and potentially a larger motor on the head, I want to have a little extra power so I can move it quickly without needing any counter weight or spring helping to push the head up.  



I was hoping the 400 oz in motor would last a little while on the Z axis, but my hand has been forced.  I was getting set up to do some test cuts when something exploded inside the power box.  The Z axis drive ate it, potentially from the current being drawn holding the head up.  So until I get the new motor and drive, I won't be doing any cutting on the machine. 



I have started the design work for the tool changer and have plans for a pneumatic cylinder, so hopefully those will be next.  I am also getting the planning for the enclosure started.  I got used to it with the X2 and doing the manual machining made such a mess I don't know how long I will last without one.


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## shooter123456

I got a new driver and tested it out with the existing motor on the Z axis.  Using the same input voltage and supplied torque, the new driver is able to move the head without any trouble.  I got a DM860T, and wow it is a world different from the TB6600s.  The motor is much quieter, there is no stepper hiss, there is no start up jump, it produces more torque and it runs much cooler.  Moving the head at 30 IPM, it is nearly silent.  When I step it up to 100 ipm, it makes a stepper noise, but it is much quieter and lower pitched (think errrrrr instead of eeeeeeeeeeee).  The only weird thing is the motor makes a strange grinding sound at 150 IPM, and only at 150 IPM.  Thats 750 rpm on the motor or 12.5 rps.  There might be some resonance there causing that issue.

I am very strongly considering swapping the TB6600s on the X and Y with DM542T drives.  If they run the same way the DM860T does, it will be much smoother and much quieter at lower speeds, and produce much more torque from the same motors.  

Here is the new driver next to the blown one.





I did some test cuts with the new driver on the Z, and I am very please with the machines performance.  Using a .375" 3 flute carbide end mill, I was able to make .1" WOC, .75" DOC, up to 38 IPM at 2500 RPM.  That is an MRR of 2.85 cu-in/min.  It handled it without chatter, but the little slip in spindle speed while the motor catches up did cause some vibration.  I wonder if there is a way to reduce that delay in spindle speed during heavy cuts because with an adaptive tool path, it is constantly loading and unloading the motor and it is very noticeable when the RPM fluctuates.  It made some nice big chips like that.



I also ran the first part under CNC control.  It was supposed to be an electronics enclosure for my micro lathe. Unfortunately, the X axis lost a bunch of steps very quickly with the first cuts, so the part will be scrapped.  I am not sure what caused the lost steps, but making the cuts less aggressive, it was able to run without losing any steps.  

Here is the first precision scrap produced on the new machine. 



I also have a bit of a backlash issue to deal with.  Each axis has about .008" of backlash, but on the old machine with thrust bearings, it was usually .002-.003.  That makes me think the bearings I used on this one are causing that backlash.  I need to get new shims to put the AC bearings in (I don't know if I mentioned I am using the deep groove bearings that came with the ballscrews at the moment), and I am currently sourcing some double nut ballscrews.  Both should hopefully reduce the backlash below .0005".


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## phazertwo

Seems like you're pushing the Z pretty hard to be running it 150 IPM.  Remember that with a stepper as your speed goes up, your torque goes down, so you're far more likely to loose steps while moving fast.  Most times I have missed steps was because of a rapid move, I eventually found a speed/accel. that worked then backed it down another 20% (125IPM X and Y to 100IPM).  For what it's worth I also have DM860's but with 600oz-in motors on the X and Y although I have a PM-940 which I would assume is quite a bit heavier.  At the end of the day it made more sense for me to run a bit slower than scrap parts.

The other scenario I have lost steps in was not using smoothing in Fusion (and the built in smoothing in my controller).  When I'm roughing I set smoothing to 0.005" in fusion, and then I set it to 0.0005" for finishing.  You can hear the difference in the machine, it literally sounds smoother, and you can tell it's not working as hard.

Your build looks very nice, I'm excited to see where it goes and it's making me think hard about re-building some of mine!

PZ


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## shooter123456

I appreciate the input Phazer.  I did a bit of math, and your mill is at least 4x as heavy as mine, so the head is likely a good deal heavier as well.  I was actually able to run the head up to 240 IPM before it would stall.  It was pretty reliable at 160, and worked at 150, the motor just made a weird sound.  It made it going up and going down, so I don't think its from the motor straining too hard under the load.  

It was the X that was giving me trouble with lost steps, and when it was losing them, it was going less than 20 IPM since 20 was the feed rate, and it was currently arcing with the Y axis.  It could be a resonance issue that caused it to lose torque only at that specific speed in the arc, and then the force of the cut was able to overcome the motor.  In theory, it should have had more than enough torque at 15-20 IPM if it could accelerate the table to 360 IPM at 60 IPS without stalling. I will try to figure out what the deal with that is though, even if it just means replacing the ballscrew and drivers, which will happen anyway.

I appreciate the kind words.  I am very excited about this machine and my plans for it seem to keep growing.


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## stioc

Neat project! What are using for your controller between LinuxCNC and the stepper drivers?


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## shooter123456

stioc said:


> Neat project! What are using for your controller between LinuxCNC and the stepper drivers?


Thank you, I am glad you like it!

I am using an inexpensive 5 axis optoisolated break out board to connect the computer to the drives through the parallel port.

The one I have is identical to this one, but I got it from a different seller: https://www.omc-stepperonline.com/s...ard-interface-mach3-cnc-router-kit-st-v2.html


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## stioc

Thanks for the info! I'm contemplating going the GRBL route for my RF31 conversion (for simplicty and my prior knowledge with it) but I keep hearing good things about LinuxCNC. I just can't decide if I want to convert my mill at all, I like the manual mill (will a DRO and power feed) for the basic stuff but CNC will allow for making new/interesting parts. Just don't have the room for two in my 2 car garage where I do everything from automotive work to woodworking and everything in between.


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## shooter123456

stioc said:


> Thanks for the info! I'm contemplating going the GRBL route for my RF31 conversion (for simplicty and my prior knowledge with it) but I keep hearing good things about LinuxCNC. I just can't decide if I want to convert my mill at all, I like the manual mill (will a DRO and power feed) for the basic stuff but CNC will allow for making new/interesting parts. Just don't have the room for two in my 2 car garage where I do everything from automotive work to woodworking and everything in between.


I have looked at GRBL, and it just didn't come out on top.  LinuxCNC is an inexpensive route, just requiring an older computer ($40 gets one that is plenty capable) and a $10 break out board.  That gives a complete operating system that lets you access the internet to transfer g-code, a text editor to edit the g-code, essentially unlimited memory, and a much faster processor.  The only place GRBL won was in space requirements.  Its a much more compact, if less powerful, system.


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## stioc

Good points! It comes down to pros/cons, they all have them. The advantage I see with GRBL is I don't have to rely on finding old computers with parallel ports (it's 2018! lol) and two the Arduino becomes a single-purpose board with GRBL (no OS to boot and much faster processing, takes all of 2 secs to boot up when I power it on) it's definitely limited by the memory of the Arduino you use where I hear really long toolpaths fill it up and they get queued up on the g-code sender. I'm using it for my small CNC router- so far I haven't had any issues with it.
LinuxCNC though seems more sophisticated with features like the backlash compensation and I hear Tormach's PathPilot is based on LinuxCNC. Your post makes me want to test it out now.
To CNC the mill or not is the question


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## shooter123456

stioc said:


> Good points! It comes down to pros/cons, they all have them. The advantage I see with GRBL is I don't have to rely on finding old computers with parallel ports (it's 2018! lol) and two the Arduino becomes a single-purpose board with GRBL (no OS to boot and much faster processing, takes all of 2 secs to boot up when I power it on) it's definitely limited by the memory of the Arduino you use where I hear really long toolpaths fill it up and they get queued up on the g-code sender. I'm using it for my small CNC router- so far I haven't had any issues with it.
> LinuxCNC though seems more sophisticated with features like the backlash compensation and I hear Tormach's PathPilot is based on LinuxCNC. Your post makes me want to test it out now.
> To CNC the mill or not is the question


All excellent points.  GRBL is an interesting solution and I bet it is more than suitable for many applications.

As for CNC vs not CNC, you probably won't know until you try it.  I started with my manual X2, converted it, then got the new one and got a chance to work manually again.  I missed manual milling.  I don't know what it is about turning handles, but I made most of the parts for the CNC conversion manually with the PM-25, just because I missed manual machining.  But then, I don't think I really start making the coolest stuff until I had CNC.  With just manual, I made a few 80% AR15 lowers and a few various doodads.  With CNC, I made an AR15 lower completely from scratch, a tiny lathe just for the fun of it, and lathe insert holders.  I am a big fan of CNC, but I really want a big manual machine hanging around as well...

Also, learning to 3D model made a huge difference.  I wasn't limited to making things I could visualize.  Starting with something, changing a little of this, a little of that, adding some of this, changing that, until you are on version 48, and you have something really cool and don't need to keep track of all of it in your head.


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## stioc

I'm exactly of the same mind as you, CNC allows you to build so much more stuff and so much faster especially if it includes radius-es, curves etc. But I think I'll miss just chucking up a part and turning handles...sorta like automatic transmission vs. manual. I wouldn't want the latter for my stop and go commute but sometimes it's just nice to row the gears yourself. I'm still struggling with Fusion360 but that just means I need to spend more time in it.

Anyway, thanks for the info and the sidebar conversation...don't want to hijack your build thread anymore!


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## shooter123456

Got the new motor in.  It is a 1000 oz in Nema 34.  It really dwarfs the smaller 40 oz in one.  It is crazy how much of a difference there is between the Nema 23s and Nema 34s.  I am not sure when I will get the new plate made to put the new motor on.  I will also need to modify a coupler for the half inch drive on the 34.  I couldn't find any couplers that went from 12.7mm to 10mm.  I would like to make some couplers one day, just because I have always wanted to make one.  The couplers I got were $5 each and came in a pack of 3 from Amazon.  

Here is the new motor next to the old one.




Here is the new coupler next to the old one.  The new ones were actually less than the old ones, ($9 vs $5) and they look much nicer.  (New one on the left)





I got a quote for 2 C7 double nut ballscrews from Linearmotionbearings2008 on ebay and he quoted me $99 for a 750mm 1605 with double nuts, and a 350mm 1605 with double nuts as well.  That quote included shipping and end machining on both ends.  He said they should be in around the middle of March.  Since I couldn't find any online that I could afford (Next offer was $300 each), I will be going with these to see how they are.


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## mrjbinok

Great thread!!  I have a new PM-25 ordered that is suppose to be here in a couple of days.  A CNC conversion is possibly in the the future, but initially I want to use the manual machine to learn on. (My first milling machine)

Since available help with a strong back and weak mind is in short supply, I have been trying to calculate how I was going to get it from the shipping container up to the bench top!!  Now I know.  I opted for terminal pickup so having the shipping company load to the back of my truck will take care of half the battle.


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## shooter123456

mrjbinok said:


> Great thread!!  I have a new PM-25 ordered that is suppose to be here in a couple of days.  A CNC conversion is possibly in the the future, but initially I want to use the manual machine to learn on. (My first milling machine)
> 
> Since available help with a strong back and weak mind is in short supply, I have been trying to calculate how I was going to get it from the shipping container up to the bench top!!  Now I know.  I opted for terminal pickup so having the shipping company load to the back of my truck will take care of half the battle.



Sounds like a great idea.  Learning is much easier in manual (in my opinion) because you can feel when something isn't quite right.  Lifting it wasn't too bad while it was taken apart, but I am 22 and in decent shape, not sure what your situation is, but keep that in mind. 

If you end up converting it to CNC, let me know and I can send you the plans for the conversion parts.  This machine was way easier to convert than my X2, and all of the parts can be made manually.  Let me know if you have any questions when you get the machine, I am always happy to help!


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## mrjbinok

shooter123456 said:


> Sounds like a great idea.  Learning is much easier in manual (in my opinion) because you can feel when something isn't quite right.  Lifting it wasn't too bad while it was taken apart, but I am 22 and in decent shape, not sure what your situation is, but keep that in mind.
> 
> If you end up converting it to CNC, let me know and I can send you the plans for the conversion parts.  This machine was way easier to convert than my X2, and all of the parts can be made manually.  Let me know if you have any questions when you get the machine, I am always happy to help!



I'm a little past 22 ( by about 46 years!!) but i have mastered the art of fulcrum leverage to lift stuff around the shop.

I picked up a rolling workbench/storage cabinet from HF the other day and it will serve as the new home for the mill.  I'm still working to attach it to the wall and getting the top leveled.  I make a few specialty tools for the HD Ironhead Sportsters so having a mill will be a welcome addition to the shop.  I've done some basic work with my brothers older Grizzly machine, but I'll be doing a lot of try this and try that plus a whole lot of Internet looking.

Thanks for the offer for help and info.  I'm sure that after I get my machine set up next week I'll have a lot more question than I have answers. lol


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## wrmiller

When I bought my PM25 I was 6 years younger than I am now (62), and while I managed to wrap the thing in a beach towel and lift it onto a 40" tool box, it is not something I recommend folks do. My wife about had a fit. 

I put 3/4" plywood on top of the tool box, and then a piece of 1/4" plate between the mill and the toolbox. Made some screw-type levelers to get the toolbox up off it's wheels and it turned out to be a decent setup.

Have fun with your new mill.


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## shooter123456

wrmiller said:


> When I bought my PM25 I was 6 years younger than I am now (62), and while I managed to wrap the thing in a beach towel and lift it onto a 40" tool box, it is not something I recommend folks do. My wife about had a fit.
> 
> I put 3/4" plywood on top of the tool box, and then a piece of 1/4" plate between the mill and the toolbox. Made some screw-type levelers to get the toolbox up off it's wheels and it turned out to be a decent setup.
> 
> Have fun with your new mill.


If you didn't take it apart first, that is really impressive! I could hardly move the thing while it was all in one piece.  

What kind of tool box do you have your mill on?  I am going to build an enclosure for mine, but I can't decide if I want to make the base or buy something.


----------



## wrmiller

shooter123456 said:


> If you didn't take it apart first, that is really impressive! I could hardly move the thing while it was all in one piece.
> 
> What kind of tool box do you have your mill on?  I am going to build an enclosure for mine, but I can't decide if I want to make the base or buy something.



I no longer have the mill, and yea, I picked it up as one piece. The beach towel was necessary as I used my forearms like a forklift under the table and put the back of the column against my chest. I was in my mid-50s at that time, and probably shouldn't have done that. I was fairly strong most of my life, and old habits die hard. At least I didn't drop it on my foot... 

Going back through my old pics, I found one that basically shows my PM25 setup. It's on a Craftsman 40" toolbox.







I don't have a pic of the levelers I made, but they were similar to a machinist's jack. Put on on each corner of the toolbox. The setup worked really well for me. If you have more questions, lets take this offline so we don't continue to hijack the OP's thread.


----------



## shooter123456

wrmiller said:


> I no longer have the mill, and yea, I picked it up as one piece. The beach towel was necessary as I used my forearms like a forklift under the table and put the back of the column against my chest. I was in my mid-50s at that time, and probably shouldn't have done that. I was fairly strong most of my life, and old habits die hard. At least I didn't drop it on my foot...
> 
> Going back through my old pics, I found one that basically shows my PM25 setup. It's on a Craftsman 40" toolbox.
> 
> View attachment 259202
> 
> 
> I don't have a pic of the levelers I made, but they were similar to a machinist's jack. Put on on each corner of the toolbox. The setup worked really well for me. If you have more questions, lets take this offline so we don't continue to hijack the OP's thread.



Thank you for the info.  I like that set up a lot, very organized and clean.   No worries about the OPs thread, its mine and this is right on subject.


----------



## shooter123456

I made some new lock nuts and machined some spacers for the AC bearings.  I suspect some of the .008" backlash was coming from the bearings I was using and I don't think they were preloaded properly.  I made 2 piece nuts with screws that can be tightened to lock the nut down on the threads.  These are much better than the lock nuts that came with the ballscrews and in my opinion, they are better than the nylon lock nuts.  Since it was an M12x1 thread, I couldn't commercial nuts for it anywhere anyway.  They use 3 4x40 screws to lock and I cut the holes so there was just a little bit of space between the nuts when the holes are aligned.  I have always had trouble with the regular lock nuts occasionally loosening up and it has ruined parts before.  I am confident that these won't move once locked.



Here it is installed on the X axis with the new coupler on the motor.



I machined some spacers so I could preload the AC bearings as well.  That was pretty straight forward but I don't have any pictures of it.  Essentially I machined a bar to the right inside and outside diameter, then parted off 3 pieces, then super glued each to a piece of steel in the spindle, and faced it until it was about .05" thick.  Using the lock nuts, I can adjust the preload on the bearings without needing shims.

I have the tool changer mostly designed now.  It will be a little while before I am ready to start making parts for it, but I will start ordering stock and parts soon.  The plan is to use a Nema 23 motor, a deep groove ball bearing, some round linear rails, and a pneumatic cylinder to run it.  I think I will use an arduino to control the changer if I can figure out how to interface it with LinuxCNC.  The plan is to have several sensors checking each step of the tool change to ensure reliability.  

The tool change will go like this:
1. Z axis return to home position (Home switch confirm head in position)
2. Spindle motor off (Relay on spindle power to ensure spindle motor off)
3. Tool changer move into position below spindle (sensor to confirm changer in position)
4. Z axis lower tool to tool changer (sensor confirm head lowers to tool tray)
5. Pneumatic cylinder release tool (sensor to confirm cylinder actuates)
6. Z axis return to home position (home switch confirm head in position)
7. Tool changer rotate to the next tool (sensor to confirm position of carousel and proper tool selected)
8. Z axis lower spindle to tool (sensor to confirm head lowers to tool tray)
9. Release pneumatic cylinder (sensor to confirm cylinder releases)
10. Retract tool changer (sensor to confirm tool changer fully retracted)
11. Z axis return to home position (home switch confirm head in position)
12. Confirm new tool in spindle (not sure how I will do this yet)

Here is the tool changer with all of the covers removed.  



Other side.



On the mill.



I used Fusion360s FEA to make sure the changer wouldn't deflect too much under the weight of all the tools.  It gave me a deflection value of .0002" at the worst position so I am confident the structure is strong enough.



With a vise installed, there will only be about 5.5" between the bottom of the tool holders and the top of the vise jaw.  I am considering a few alternatives such as adding a Z axis to the tool changer so it lifts up and out of the way when not in use, and the table can move all the way forward (closest to me) when changing tools, so hopefully it will be mostly out of the way.  I don't think it will be too much trouble though, since I don't plan to have any tools sticking out more than 2 inches, and I don't often work with parts sticking more than 3.5" out of the vise.  Im pondering the idea of some kind of quick release for the tool changer so I can lower the tool carousel out and remove it completely for when I work with taller parts.

If anyone has any ideas or suggestions, I am all ears.  I have never tackled a project like this and could use all the help I can get.


----------



## wrmiller

Quite the project you have going here. It will be interesting to see this thing in action when you get it done.


----------



## phazertwo

Arduinos are nice, but considering the amount of I/O you are talking about, it seems it would be very beneficial to up to a full PLC.  It would open up a lot of I/O and have the advantage of being very expandable.... Plus they are industrial devices, so they should last forever on a hobby mill.

I would suggest looking into a Click PLC from automation direct (Starts at $69).  They are crazy cheap for the quality you get, the programming software is FREE, and you have tons of add on capacity (digital I/O and analog).  I have used them a few times for smaller projects at work and they seem to work out very nice.  I plan to install one on my mill to automate things like the motor fan, cabinet fan, coolant level sensor, PDB safety (sensing if spindle is spinning, possibly tool in spindle/not in spindle).  Relatively simple things that I don't need to tie up I/O on my Acorn board with, though it will take up at least 1 input for an error condition.  One could even add an HMI for better visibility and control.

Here is a link the the PLC, and a cheap HMI to go with it... if your into that kinda thing...
https://www.automationdirect.com/clickplcs/index

https://www.automationdirect.com/ad...els/3_inch_Panels_-a-_Accessories/EA3-S3ML-RN

Just a thought.
PZ


----------



## shooter123456

phazertwo said:


> Arduinos are nice, but considering the amount of I/O you are talking about, it seems it would be very beneficial to up to a full PLC.  It would open up a lot of I/O and have the advantage of being very expandable.... Plus they are industrial devices, so they should last forever on a hobby mill.
> 
> I would suggest looking into a Click PLC from automation direct (Starts at $69).  They are crazy cheap for the quality you get, the programming software is FREE, and you have tons of add on capacity (digital I/O and analog).  I have used them a few times for smaller projects at work and they seem to work out very nice.  I plan to install one on my mill to automate things like the motor fan, cabinet fan, coolant level sensor, PDB safety (sensing if spindle is spinning, possibly tool in spindle/not in spindle).  Relatively simple things that I don't need to tie up I/O on my Acorn board with, though it will take up at least 1 input for an error condition.  One could even add an HMI for better visibility and control.
> 
> Here is a link the the PLC, and a cheap HMI to go with it... if your into that kinda thing...
> https://www.automationdirect.com/clickplcs/index
> 
> https://www.automationdirect.com/ad...els/3_inch_Panels_-a-_Accessories/EA3-S3ML-RN
> 
> Just a thought.
> PZ


I will have a look at them.  The reason I picked arduino is because I already have 2 arduino megas, and they have 54 input/output pins and should have more than enough for the sensors and driving the stepper.  I am also already familiar with the programming language, and they are cheap, so I can blow them up without feeling bad about it.  It also has digital and analog I/O, can (in theory) communicate with the PC through the serial port, and has a bunch of add ons that are cheap and easy to use.  

I'll look at those PLCs in more detail, though I am not entirely sure what they do...  At the very least, they look beefy and well made, which would be a big plus.


----------



## phazertwo

PLCs are basically small industrial computers.  Pretty much anything that is automated has a PLC these days, even the Acorn controller that I'm running is considered a PLC with a Beagle Bone computer piggy backed to it.  Programming them is incredibly easy, no experience with any type of C programming is needed.

I used Arduinos a lot in the past, but after finding this Click PLC, I've pretty much given up on them.  PLCs are optically isolated, so you have to try pretty hard to blow one up (and I have tried).  I do have quite a bit of experience with them through work... so that helps too.  As with most things these days there is an incredible amount of material on YouTube to walk you through almost anything you need to know with them.

PZ


----------



## shooter123456

Its upgrade time! I've got some new parts coming for the mill so I figured I would post a quick update, as well as summarize the costs for everything so far in case anyone else is looking to go the same route.  

Parts and costs all including shipping:
2 400 oz in Nema 23 steppers - $67
1 1000 oz in Nema 34 stepper - $69.79
2 DM542T stepper drivers - $67.90
1 DM860T stepper driver - $53.95
1 550 mm SFU1605 ballscrew - $65
1 750mm DFU1605 ballscrew - $50
1 350mm DFU1605 ballscrew - $50
6 7001 AC bearings - $15.54
3 flexible couplers - $15
4 inch mill vise - $100
PM-25 mill - $1649
350 watt power supply - $30
240 watt power supply - $20
Break out board - $10
Aluminum stock - $10
Total - $2271.18

I am hoping to install the new drivers today.  I am hoping they run much smoother than the TB6600s.  I think the ballscrews are supposed to be delivered tomorrow, so I will update once I figure out if they are any good.  

For the tool changer, I have a piece of 4 inch aluminum bar 8" long being delivered tomorrow to make an air cylinder.  I also have 36" of 12L14 steel for tool holders coming.  The mill will probably be used in lathe mode to make most of those.  I also made the umbrella a little bit bigger to hold 12 tools instead of 10.

I also finished the first part CNCd part made on the machine.  I got the backlash figured out and I got the X axis to stop losing steps.  It is the electronics box for my micro lathe.  This machine really can rip up some metal.


----------



## stioc

Nice! I can't wait to see the tool-changer built and functioning, that's pretty neat!


----------



## phazertwo

shooter123456 said:


> Its upgrade time! I've got some new parts coming for the mill so I figured I would post a quick update, as well as summarize the costs for everything so far in case anyone else is looking to go the same route.
> 
> Parts and costs all including shipping:
> 2 400 oz in Nema 23 steppers - $67
> 1 1000 oz in Nema 34 stepper - $69.79
> 2 DM542T stepper drivers - $67.90
> 1 DM860T stepper driver - $53.95
> 1 550 mm SFU1605 ballscrew - $65
> 1 750mm DFU1605 ballscrew - $50
> 1 350mm DFU1605 ballscrew - $50
> 6 7001 AC bearings - $15.54
> 3 flexible couplers - $15
> 4 inch mill vise - $100
> PM-25 mill - $1649
> 350 watt power supply - $30
> 240 watt power supply - $20
> Break out board - $10
> Aluminum stock - $10
> Total - $2271.18
> 
> I am hoping to install the new drivers today.  I am hoping they run much smoother than the TB6600s.  I think the ballscrews are supposed to be delivered tomorrow, so I will update once I figure out if they are any good.
> 
> For the tool changer, I have a piece of 4 inch aluminum bar 8" long being delivered tomorrow to make an air cylinder.  I also have 36" of 12L14 steel for tool holders coming.  The mill will probably be used in lathe mode to make most of those.  I also made the umbrella a little bit bigger to hold 12 tools instead of 10.
> 
> I also finished the first part CNCd part made on the machine.  I got the backlash figured out and I got the X axis to stop losing steps.  It is the electronics box for my micro lathe.  This machine really can rip up some metal.
> View attachment 262219
> 
> 
> View attachment 262220



That's an awesome looking box!  Keep up the good work!

PZ


----------



## shooter123456

I got the ballscrews in, but all I will say about them is that they are not good.  I won't post any more details until I have sorted out the issue with the seller. 

I made new pulleys for the spindle and motor to speed it up.  I managed to get it to about 5450 RPM.  It sounds better than it did before and I did a few test cuts and it ran very well.  After about 30 minutes of cutting, the spindle was very hot though.  My laser thermometer read about 140 degrees F.  I will likely need to swap those out for some AC bearings in the near future.  That was the plan anyway so I am not worried about it.  There was no slipping of belts even in the heaviest cuts I tried.  I actually managed to get the axis motors to stall before the spindle motor stalled.  It was able to take several very stout cuts without any issues.   I will definitely need an enclosure soon because it was chucking chips easily 10 feet away.  I am currently looking for a new spindle motor for the machine to get a bit more torque and speed it up a little bit more.  It has a 2500 RPM motor, so if I can find one that will do 4000, the spindle will run just under 9000 RPM.   The current motor is doing ok, but it takes too long to catch up to torque requirements during heavy cuts.  I think I will end up using that motor on a lathe I am designing and get a new one for the mill.

I am also working on machining the air cylinder for the auto tool changer.  I have made most of the parts for it, I just need to order some components for it before it will be ready to use.  I have the design for mounting it and the spring washers all set out, and I will be using the new 5500 rippems to make the parts.  I should be able to get 2300 lbs of force from the air cylinder and the springs will be arranged to give me about 1900 lbs of holding force.  I am hoping that will be enough.   If not, I can get some stronger springs and increase the pressure in the air cylinder.  I did take some ideas from The GRIZZ build over on CNCzone, so if it looks familiar, give them credit, they gave me the idea. I have stock for the tool holders, but I have not had a chance to machine them yet. They are going to be very similar to TTS holders and are going to be made from 12L14.  If that ends up not being enough, I will make new ones out of 4140.  I am a hobbyist though, so I doubt they will see enough use to be worn out. 

For the enclosure, I am trying to decide between MDF and sheet metal.  I have zero experience with sheet metal and I have none of the equipment for working with it, so that might be a problem.  But I also think sheet metal would work better and would be much nicer.  I have gone back and forth on that.  I have always wanted to do sheet metal stuff, so a massive first project to learn the ropes might work, right?

I am still loving the machine.  My 2 PM machines have just about filled a 35 gallon trash can with aluminum chips.  From what I have seen this machine do in the last few days, I have a feeling that problem will only be getting worse.  Here are some pictures.


----------



## phazertwo

Really nice looking work!

Where did you order your ball screws from?  I'm starting to design a router and any input/advice on that front would be much appreciated!

PZ


----------



## shooter123456

phazertwo said:


> Really nice looking work!
> 
> Where did you order your ball screws from?  I'm starting to design a router and any input/advice on that front would be much appreciated!
> 
> PZ


I got them from linearmotionbearings2008.  I won't go into details until the whole thing is settled, but I would not recommend.


----------



## phazertwo

shooter123456 said:


> I got them from linearmotionbearings2008.  I won't go into details until the whole thing is settled, but I would not recommend.



I assume that's an ebay seller?

PZ


----------



## shooter123456

phazertwo said:


> I assume that's an ebay seller?
> 
> PZ


Yes, sorry.  That is his ebay username.


----------



## alfaspider

mrjbinok said:


> Great thread!!  I have a new PM-25 ordered that is suppose to be here in a couple of days.  A CNC conversion is possibly in the the future, but initially I want to use the manual machine to learn on. (My first milling machine)
> 
> Since available help with a strong back and weak mind is in short supply, I have been trying to calculate how I was going to get it from the shipping container up to the bench top!!  Now I know.  I opted for terminal pickup so having the shipping company load to the back of my truck will take care of half the battle.


------

When you ordered the PM25- Did you consider the DRO upgrade they offer?  I assume there are cheaper DIY scales and read outs, but the one offered looks to be specific to this mill with a larger read out panel.  Only down side appears to be conflicted space with the z axis handles at top right of the column?

Has anyone had experience with the PM installed DRO, and is it worth the extra cost ?

Last time I checked the DRO upgraded unit was not available, so have some time to think about it- or just order a basic mill ?

PM customer support seems to be well regarded, but wonder if actual users think the extra cost is worth the wait?

Thanks,


----------



## mrjbinok

alfaspider said:


> ------
> 
> When you ordered the PM25- Did you consider the DRO upgrade they offer?  I assume there are cheaper DIY scales and read outs, but the one offered looks to be specific to this mill with a larger read out panel.  Only down side appears to be conflicted space with the z axis handles at top right of the column?
> 
> Has anyone had experience with the PM installed DRO, and is it worth the extra cost ?
> 
> Last time I checked the DRO upgraded unit was not available, so have some time to think about it- or just order a basic mill ?
> 
> PM customer support seems to be well regarded, but wonder if actual users think the extra cost is worth the wait?
> 
> Thanks,



I didn't really look at the DRO upgrade..... Tight budget just to get the machine (my first mill as well) restricted how much I had to spend initially.  I've had only limited contact with support as yet.... my experience and everything I have read across the web is positive.  The first thing I decided that I would really need is a power lift for the head assembly.  I have all the parts to do the upgrade now..... just need to fabricate a mounting for the motor and wire it up.

Most all of what I anticipate using the machine for is pretty basic.  The DRO would be overkill for me I think, but the addition of a horizontal feed is looking more and more likely as I surf the web for instructions.  A downturn in health is keeping me out of the shop for now, but hopefully that will change soon.

Hopefully someone else with DRO knowledge will chime in soon and answer your other questions.


----------



## shooter123456

Slow going recently with school getting near the end of the semester and all the nonsense that brings.  

I ordered some new bearings for the spindle since the stock ones are getting really hot at the higher speed.  I am a bit worried about these though because the spindle bearings are small.  The lower is a 7007B bearing and the upper is a 7005B.  The upper bearing is smaller than the upper bearing on my X2.  The tapered rollers are rated at 43,000N for the lower and 30,000N for upper compared to the AC bearings which are 17,500N and 11,300N.  Thats 73,000N compared to 28,800N. I don't know if that difference is going to give me a problem with rigidity, but the new bearings are rated for 9500 and 13,000 RPM, so I should be able to get the spindle going a little bit faster before it starts over heating.

I installed the new stepper drives which made a big difference.  The new drives are DM542T from stepper online.  The motors are running much quieter and smoother now.  I no longer have any stepper hiss going on and under 10 IPM, they are darn close to silent.  The TB6600s certainly work, but the DM542Ts sound much better and so far I haven't had any issues with lost steps.  

The ballscrews sound rough, but I am getting below .001" backlash on the Y and around .0015" on the X.  The X axis screw is currently wiggling like a freshman at her first frat party (or so I would guess, never been to a frat party...) at the floating end and the nut shakes in the holder a bit from the screw not being straight.  It will definitely reduce the life of the screw and it sounds rough, but these screws were refunded and I should be able to get a year or two out of them. 

I am just about done with the air cylinder for the draw bar and I have belleville springs in.  The draw bar should give me between 2100 and 2500 lbs of pushing force depending on how much pressure I use.  The springs are rated for 900lbs working load and 1100 when compressed.  I will be running pairs so that should be 1800lbs on the drawbar with 2200 to release.  I have the stock all roughed out for the air cylinder mounting and drawbar parts, I just need to run the machine to drill some holes and mill a few parts.  

I have made a few changes to the design of the power draw bar as well.  I have replaced the entire quill assembly with an aluminum plate that will hold a 6007 C3 bearing rated for 15,000 RPM.  The spindle pulley will have one part slide into the bearing and the bore will be a close fit for the spindle shaft.  That should support the spindle without needing to deal with the extra 2 large bearings.  The plate will also hold the air cylinder and mount the motor.  The power draw bar assembly will be floating on shoulder screws and when the cylinder is actuated, it will pull itself up until a steel plate grabs a "top hat" part on the spindle, then it will compress the spring washers and release the tool.  The entire thing is made of aluminum, mostly .75" plate, except the top hat which is going to be 12L14 and the plate that grabs the top hat, which is mild steel.  I probably don't need to do it with such thick aluminum plate, but the recycling center near me always has a bunch of them that are roughly 9"x30" which I pay roughly $20 for.  Ordering online usually costs at least 4 times for the thinner material that would be suitable.  I think it is MIC-6 or similar plate because it is definitely cast and it is very flat and consistent over the surface.  

The mill has also been used to make soft jaws for the lathe so I can make the tool holders as concentric as possible.  I have 8 holders partially finished now, with the .75" shank done and the undercut for the collet finished.  6 of which have had the body also roughed on the mill.  Right now, I think it is 3 ER20 holders, 3 set screw, 1 face mill arbor, and 1 drill chuck holder.  

Something I forgot to mention is that I tested a 2" 4 insert face mill (one of the super cheap ebay ones) with some aluminum specific inserts, and it was absolutely shredding the plate.  It flung chips at least 6 feet from the mill too and took excellent cuts with an incredible surface finish.  I was cutting at least .05" deep, 1.25" wide, at something like 20 IPM.  I have some short videos of that that I may upload eventually.

Here are the new drivers next to the old ones.  The new ones are much heavier as well, even though they don't have an aluminum heat sink (even though the TB6600s were largely for show, very little contact with the sink and the rest of the parts).






Here is the air cylinder.  If you recognize it, its because its a design you can purchase from Hoss.  I didn't design this one myself.  Once I have it assembled and tested (its been tested and works, just have to epoxy in the seals) completely, I will chuck it up and turn the outer diameter so it is concentric and the same diameter.





Here is the air cylinder disassembled.





Some soft jaws.  Lighting is terrible because the new mill is under the garage door and there are no overhead lights.  The rest of the light is blocked by mill head.  





Another look.





One of the jaws while being machined.





Here is a model of the new plate for the head.  This part has already been machined, but I forgot to take a picture of the finished part.  





Here is another look at the power draw bar model.  





Another angle.





Here is a dissassembled view of the parts I need to make.  They are pretty simple parts and now that the stock is roughed out, it shouldn't take long to finish it up.





I have started looking into a new motor for the spindle.  I want to eventually speed it up to around 10,000 RPM which means I probably need a faster motor.  I have been looking at putting a DMM servo on it, which would give me 3000 RPM continuous and 5000 top speed, which could be pulleyed to 6000 and 10,000.  I am talking to them now about what those ratings mean to see if that would be a viable solution.  I am also looking at 1-2 HP AC induction motors run with a VFD.   I don't know if it will be worth the trouble getting the computer to control the stock spindle motor if it will be replaced soon.  Once school gets out (end of next week) I start working full time for the summer, so I will have some extra money to spend.  

As always, suggestions, ideas, questions, criticisms, etc are appreciated.


----------



## phazertwo

Curious what is your major?

I really like the idea of the "pinch" style PDB, especially when changing to AC bearings that are rated for a much lighter load.  I think you will be okay with the lighter bearings (at least I hope so since I am doing the same thing!), just don't take massive cuts with huge tools.  I would also use high quality grease and monitor the heat and vibration periodically.  Generally a bearing will let you know it's on it's way out before it causes any problems.  Also something to consider is a greaseable setup, so you can get some fresh grease in there every so often.

That air cylinder you built is freaking awesome.  Makes me want a lathe SUPER bad...

Only question I have about your PDB/Belt drive is about the 3rd bearing.  Normally, having 3 bearings on a shaft over constrains it and will cause a bearing to fail prematurely.  I cannot tell by the pic if that bearing is actually constraining the spindle or maybe it's floating (the shaft is locating it).  Other than that, looks like a solid design, and I can't wait to see it in action!

Also, keep us posted on the DMM servo as a spindle motor.  A few others have brought it up and it's a very interesting idea.

PZ


----------



## shooter123456

phazertwo said:


> Curious what is your major?
> 
> I really like the idea of the "pinch" style PDB, especially when changing to AC bearings that are rated for a much lighter load.  I think you will be okay with the lighter bearings (at least I hope so since I am doing the same thing!), just don't take massive cuts with huge tools.  I would also use high quality grease and monitor the heat and vibration periodically.  Generally a bearing will let you know it's on it's way out before it causes any problems.  Also something to consider is a greaseable setup, so you can get some fresh grease in there every so often.
> 
> That air cylinder you built i freaking awesome.  Makes me want a lathe SUPER bad...
> 
> Only question I have about your PDB/Belt drive is about the 3rd bearing.  Normally, having 3 bearings on a shaft over constrains it and will cause a bearing to fail prematurely.  I cannot tell by the pic if that bearing is actually constraining the spindle or maybe it's floating (the shaft is locating it).  Other than that, looks like a solid design, and I can't wait to see it in action!
> 
> Also, keep us posted on the DMM servo as a spindle motor.  A few others have brought it up and it's a very interesting idea.
> 
> PZ


I am a microbiology major.  Most people assume I would be some kind of engineering major, and if I could do the math, I probably would be.  I actually think I could handle engineering now, but I have one semester left before I graduate and going to engineering would basically mean starting all over.  

I will look into a way to grease the bearings.  They should be relatively accessible so adding a grease nipple somewhere shouldn't be too difficult.  I will cross that bridge when I get there I suppose.  

Thank you for the kind words about the air cylinder.  It was a bunch of work, but it was fun to make and saved me a ton of money over buying one.  Looking at the tormach PDB, I should be saving around $640 by building from scratch. 

The top bearing should be located on the shaft.  I am hoping to have a good bit of play in the plate, so I can position it where the spindle shaft wants to be, then secure it.  It is only there because I thought it might be problematic having heavy belt tension on that part of the shaft, unsupported.  The belt will be pulling on the shaft 6" from the upper bearing (I guess middle bearing if we consider three bearings) and the spindle shaft gets as thin as .1". 

I spoke with a guy at DMM and the set up he recommended was about $500 and he said performance would be similar to a regular AC motor with VFD, except for when rigid tapping.  I might have trouble spending the extra $200ish on a DMM just for slightly better performance rigid tapping.  We will see though.


----------



## phazertwo

I was thinking engineer... you have a knack for this stuff, that's obvious.

I wonder how well a DMM will work for ridged tapping when run through a belt drive.  I know that Centroid says that the encoder must be on the spindle, at 1:1 in order for ridged tapping to work.

Here is what I think I'm going to do for spindle bearing greasing.  It's going to require a new seal housing, but that shouldn't be any big deal.  Just add a little bit of 1/8" copper tubing and you should be good to go.










For the lower bearing I think we can just go right through the quill.  We would need to re-design the cap at the bottom of the quill to have a seal, but again, shouldn't be too big of a deal.

PZ


----------



## shooter123456

Wow, that is a detailed model.  It looks excellent! I will have to look into rigid tapping and such a little bit more.  The DMM rep said that the motor can run continuously at 5000, but that leads to a 50% drop in torque.  So I could do 2 to 1 and have 6000 rpm with full torque, and 10000 with half.  It may end up being too much trouble, and I can just make a tapping head instead.  

Do you have any plans for a 1 shot oil system?  I am thinking that somewhere down the line, I will need to add that, as well as something to grease the ballscrews.


----------



## shooter123456

I finished all of the parts that will be done on the mill for the power draw bar.  It is a total of 7 parts.  I just need to make 3 parts on the lathe (top hat, spindle pulley, drawbar) and this thing will be ready to go.  I also milled steel on the mill for the first time and it cut very well, even with my worn out 4 flute carbide end mill.  I need to come up with a way of supporting the parts better, because when I cut the slot, it deformed with the following passes and led to a slight angle on one of the sides.  Shouldn't affect the part function at all though.

Here are the 7 finished parts.  The steel one is the bottom left.





These two are the first cuts I did on the steel plate.  I tried to capture the finish as best as I could.










Here it is cutting one of the parts with a 3 flute .125" end mill.





Here all the parts are just stacked up waiting to be screwed together.


----------



## phazertwo

Damn dude, you work fast.  Good looking parts too.  You're really making me want to get some more spindle time!

The model is coming along, I've decided to include as much detail as I can so I feel more comfortable designing parts to the model.

My machine has an automatic oilier, so I don't have to worry about it.  Mine came with the machine so I don't know how much it cost, but it's nice to have.  Right now it's on a timer, but I plan to change it over so the Acorn is controlling it, so it will only count time that the machine is actually moving...

PZ


----------



## shooter123456

PZ, you must have jinxed me.  I was booking and cooking with this stuff until you said I work fast.  Then no progress for a month.  Had to deal with finals, then I took a trip out to Vegas to see my parents, so no time to work in the shop.  

Got most everything done for the power draw bar now.  I made a new drawbar, new spindle pulley, and finished machining the air cylinder.  I got everything assembled and test fit and so far everything seems like it should work.  

Chucked up the cylinder to turn everything to the same diameter.





Here is the finished product.  I left a bit of extra material at the top because I thought the air tube connector threads would be getting a little too close to the edge.  I don't think it makes it look bad though.





The new draw bar, just before being threaded.  The threads on my R8 collet aren't straight, so its a bit of a challenge threading it on on the mill, but it works.





Here is everything up for the test fit.  So far, everything seems to fit right.  I apologize for the picture quality.  The glass covering my phones camera shattered and I haven't replaced it yet.  















All that is left is the top hat for the spindle, and I will be ready to try it out.  Fingers crossed that it goes well.


----------



## phazertwo

Sometimes life just pops up.  Again, nice looking parts!

PZ


----------



## tcarrington

A very nice addition to a very nice small mill. I think a time / motion study will show changing tools is a large contributor. Have a consistent pressure on the collet might also be an advantage. Great job!


----------



## macardoso

Shooter123456, I have the exact same shop made air cylinder sitting on my workbench. Would you mind posting what beville springs you ordered? I haven't had a chance to finish the whole system yet, but I want to jump back into it!












The rest of my pictures are of the 18 tool ATC for the G0704.  I wanted a challenge so it is a swing arm type.  It has been on hold for a few months but I am pretty close to finishing it up.


----------



## HellawellCustoms

This thread is absurd! I can't believe what I am seeing! An absolue genius at work! Mad respect for taking a project like this on. This makes me feel very small! Can't wait to see that ATC going!


----------



## shooter123456

macardoso said:


> Shooter123456, I have the exact same shop made air cylinder sitting on my workbench. Would you mind posting what beville springs you ordered? I haven't had a chance to finish the whole system yet, but I want to jump back into it!
> 
> 
> The rest of my pictures are of the 18 tool ATC for the G0704.  I wanted a challenge so it is a swing arm type.  It has been on hold for a few months but I am pretty close to finishing it up.



I went with these springs from McMaster Carr. https://www.mcmaster.com/#9712K437

Working load is 900 lbs and I have them doubled to give me 1800 lbs.  I have them in 3 stacks of 4 so (())(())(()) which doubles force and triples travel.  I would love more details on your tool changer.  I considered one like that, but an umbrella one seemed much simpler.  Cudoz for taking on such a difficult project.  I have never seen one of those on a small hobby mill before.  

Nice air cylinder, looks very familiar


----------



## macardoso

shooter123456 said:


> I went with these springs from McMaster Carr. https://www.mcmaster.com/#9712K437
> 
> Working load is 900 lbs and I have them doubled to give me 1800 lbs.  I have them in 3 stacks of 4 so (())(())(()) which doubles force and triples travel.  I would love more details on your tool changer.  I considered one like that, but an umbrella one seemed much simpler.  Cudoz for taking on such a difficult project.  I have never seen one of those on a small hobby mill before.
> 
> Nice air cylinder, looks very familiar




Thanks for the info and compliments!  I should probably write up a new post on it - maybe this weekend. I'll throw a link here.  I like design challenges so I figured why not. I haven't seen anything other than Dave Decaussin's ATC (



). That guys is ridiculous, I can't touch his stuff and how quickly he gets stuff out.  Started it maybe 2 years ago, took maybe 2 months to design in Inventor, made 95% of the parts in my college machine shop whenever I had time, and spent probably a year (off and on) designing the software and Mach 3 interface. It runs on MODBUS over USB and cycles nicely.  I haven't actually put it on the mill yet but I have a test fixture to run it on. It holds 18 tools (TTS style) and can hold up to a 2" diameter tool (4 if you are willing to have 2 empty pockets) and up to about 4 pounds.  There are 3 air cylinders (Tool extension, swing arm, and drawbar), 2 steppers with encoders (swing arm and drum), and maybe 12? inductive proximity sensors.  The drum is a geneva wheel and can pre-index the tools.  It has a tool to tool time of around 3 seconds, although 5 is more comfortable.

I got pulled into other projects (new control panel with AC servos and my new lathe) but maybe you can give me the kick to get working on it again.


----------



## macardoso

Shooter, here is the new post (don't want to hijack this awesome build you are doing)

https://www.hobby-machinist.com/threads/g0704-swing-arm-atc.70055/


----------



## shooter123456

macardoso said:


> Thanks for the info and compliments!  I should probably write up a new post on it - maybe this weekend. I'll throw a link here.  I like design challenges so I figured why not. I haven't seen anything other than Dave Decaussin's ATC (
> 
> 
> 
> ). That guys is ridiculous, I can't touch his stuff and how quickly he gets stuff out.  Started it maybe 2 years ago, took maybe 2 months to design in Inventor, made 95% of the parts in my college machine shop whenever I had time, and spent probably a year (off and on) designing the software and Mach 3 interface. It runs on MODBUS over USB and cycles nicely.  I haven't actually put it on the mill yet but I have a test fixture to run it on. It holds 18 tools (TTS style) and can hold up to a 2" diameter tool (4 if you are willing to have 2 empty pockets) and up to about 4 pounds.  There are 3 air cylinders (Tool extension, swing arm, and drawbar), 2 steppers with encoders (swing arm and drum), and maybe 12? inductive proximity sensors.  The drum is a geneva wheel and can pre-index the tools.  It has a tool to tool time of around 3 seconds, although 5 is more comfortable.
> 
> I got pulled into other projects (new control panel with AC servos and my new lathe) but maybe you can give me the kick to get working on it again.


Dave does some really cool stuff for sure.  Though he gets stuff done fast because he is a professional and has professional equipment.  He was one of the founders of FADAL, but I still really like the stuff he has made.  

I really like your work, it looks very well designed and thought out.  I wish I had a mechanical engineering background like you, I feel like it would make all of this stuff easier to understand.


----------



## macardoso

shooter123456 said:


> Dave does some really cool stuff for sure.  Though he gets stuff done fast because he is a professional and has professional equipment.  He was one of the founders of FADAL, but I still really like the stuff he has made.
> 
> I really like your work, it looks very well designed and thought out.  I wish I had a mechanical engineering background like you, I feel like it would make all of this stuff easier to understand.




That is very true, I could probably get stuff done faster with a VMC in my garage.

I appreciate that.  Honestly it looks like you are doing just fine.  I feel like it just takes me forever to get stuff done, and you blew through that (and have great looking parts to show)


----------



## macardoso

shooter123456 said:


> I spoke with a guy at DMM and the set up he recommended was about $500 and he said performance would be similar to a regular AC motor with VFD, except for when rigid tapping.  I might have trouble spending the extra $200ish on a DMM just for slightly better performance rigid tapping.  We will see though.



My spindle is a 750W DMM servo with a DYN3 drive.  It's nice, but I never could get it tuned to handle the interrupted loads of cutting. It had to be de-tuned significantly or it would chatter like crazy when cutting.  I hear the DYN4 is much better though. If I had to go it again, I would do an AC motor with VFD.  Even better would be a permanent magnet AC servo motor running open loop (some VFD's can do this). I never bothered to set up rigid tapping even though I had the capability.

That being said, my new control panel will be running another AC servo spindle , but this one will be using an Allen Bradley Ultra 3000 drive and 1.8kW motor.


----------



## macardoso

shooter123456 said:


> Wow, that is a detailed model.



Something you might want to consider.

http://benchtopprecision.com/bf20-3d-model/

They should be charging more for it.  I bought it years ago and it really was worth every penny. Accurate enough to match my machine (although you have to double check, ya know, Chinese QC...


----------



## shooter123456

macardoso said:


> Something you might want to consider.
> 
> http://benchtopprecision.com/bf20-3d-model/
> 
> They should be charging more for it.  I bought it years ago and it really was worth every penny. Accurate enough to match my machine (although you have to double check, ya know, Chinese QC...


I think the one I have is suitable for everything I need.  Its not super detailed, but the important parts are accurate.  I try to avoid spending anywhere I don't have to since there isn't a ton of money to go around.  Maybe after college. 

I am starting to doubt the idea of getting a servo, since they are expensive and I kind of doubt it will be all that much better.  I have started looking for an AC motor that will be suitable.  I found several 56C motors, but they are way too damn big.


----------



## shooter123456

Everything is mounted up and tested.  So far so good.  The spindle threads aren't straight so the top hat wobbles a little bit.  I get a little bit of vibration at 5000 rpm now, but it will do just fine.

I tested the drawbar with a 2 inch face mill doing .75" WOC, .1" DOC at 25 IPM and it didn't pull out at all.   That is 1.875 cuin/min I was able to make the belt slip and there was no pull out.  Right now, the air cylinder can release the tool just fine at 70 PSI, so I can probably tighten the drawbar even more.  I just need to seal some air leaks and it will be good to go.


----------



## macardoso

shooter123456 said:


> Everything is mounted up and tested.  So far so good.  The spindle threads aren't straight so the top hat wobbles a little bit.  I get a little bit of vibration at 5000 rpm now, but it will do just fine.
> 
> I tested the drawbar with a 2 inch face mill doing .75" WOC, .1" DOC at 25 IPM and it didn't pull out at all.   That is 1.875 cuin/min I was able to make the belt slip and there was no pull out.  Right now, the air cylinder can release the tool just fine at 70 PSI, so I can probably tighten the drawbar even more.  I just need to seal some air leaks and it will be good to go.



Awesome job.  Can’t wait to get mine finished.  That’s a hell of a cut for this mill!


----------



## shooter123456

Well that didn't take long... I had the day off on Monday and spent the day working on the mill and I conked out the spindle bearings.  This was expected since they aren't meant to be run at 5500 RPM, it was just a matter of time.

I finished 2 parts that had a total spindle time of about an hour each, let the machine rest for about an hour and half while I went to the store and got some lunch, then set up some new tool holders (ordered some TTS holders, these things are nice!) and started the third part, I stopped it before the first cut after the spindle had been on for about 30 seconds (height offset wasn't right) and it went from 5500 to zero in like 2 turns.  It was almost immediate.  I touched the spindle and it was burning hot and no longer rotating freely.  Luckily, I had a set of angular contact bearings ready for just such an occasion.  

Swapping the bearings was relatively simple.  I made a simple tool to remove the lower bearing nut and just used a pipe wrench on the top nut. The top nut was terribly machined, its a lock nut and the slots that were cut into it are nowhere near straight.  Not a huge deal, but its a rotating part that will certainly need to be replaced if I want to get it moving faster.  The spindle was tapped out of the housing with a deadblow hammer and came out pretty easily.  The bearing cups fell right out as well.  They were a bit of a loose fit which I was surprised by.  I thought I would need to tap them out.  Since the AC bearings are shorter than the tapered rollers, I had to turn 2 spacers, but those went on with no trouble.  The reassembly was easy enough.  I stuck the spindle in my lathe and used sand paper to clean up the non contact parts just so it looked a little better and I touched up the bearing seats a little to remove any burrs or raised edges.  I stuck the spindle in the freezer for a few minutes while I heated the bearings and spacers with a hair dryer.  The bottom one slid right on and got screwed in, but the top one had to be forced in with the lock nut.  It didn't take much pressure to get it to slide on, but it took more than just hand pressure.   I reassembled and put it back on the machine to let the bearings break in a little bit.  I used regular automotive bearing grease to grease them.  The spindle wasn't noticeably quieter with the new bearings, but the loudest one is the very top one which wasn't replaced.  I have started questioning whether that one is really needed anyway, but it doesn't get hot at all so I haven't been worrying about it.  After 45 minutes or so of slowly ramping up the speed, I started machining the third part.  There was no noticeable loss of rigidity from the spindle and all of the same cuts were handled just fine. After about 2 hours of total spindle run time, the spindle was noticeably cooler than with the tapered rollers (again, to be expected).  

Here are the new bearings compared to the old ones.  I thought these were surprisingly small since my X2 used the same size lower bearing, but a much larger upper bearing.  It may not matter, but I figured they would be larger. 






Unfortunately, the third part was scrapped as well.  There was an issue with the tool offset and I messed up a tool path in fusion.  I need to figure out how to do the automatic tool height offset with LinuxCNC.  The first part had no problem at all, but the second part had multiple issues with the offsets not working right.  I also found the X axis slowly and consistently drifting to the right.  The first operation is a roughing pass all the way around the part to get the stock to the right size, and looking at the right side dead on, you can see each pass is slightly farther over.  Since it is consistent, I am guessing it is probably an issue with backlash, so I will need to check that before making more parts.  Another issue I need to address is with the air cylinder.  After sealing all the leaks at the connection points, I was able to hear a slight hiss from one of the exhaust in the solenoid when the other channel is open.  When there is air pressure going to the retract side of the cylinder, the exhaust for the expand side starts leaking.  I am guessing that air is escaping where one of the spacers meets the piston since there is no seal there.  If it ends up being a problem, I will just take the cylinder apart, use some silicon to seal those areas, and go from there.


----------



## shooter123456

I couldn't deal with the chips getting everywhere anymore, so I decided to put a short hold on the tool changer to get going on the enclosure.  I originally planned to try to do it with sheet metal, but after trying to make a small simple part without a brake and shears, I decided that just wasn't going to happen.  Looks like MDF is the material of choice.  I used it on my X2 enclosure and sealed with epoxy paint and that held up fine for a year until the PM25 came and that mill stopped being used.  

I am not very good at working with MDF or wood, so this might end up being a bit of a hack job.  I plan to use plywood for the base and MDF for the body, acrylic for the windows and aluminum for the doors.  I am going to machine a 4 piece frame for each door and they will slide on drawer sliders I used on the X2.  I am hoping to just use the sliders on the top away from the chips and then something simple to support the doors on the bottom.  I ordered 2 LED floodlights to light it up inside and I am planning to make a fogbuster type coolant system to use for the coming months until I figure out how to handle the flood coolant.  I will need to do some waterproofing of the electronics before I can do that.  I plan to put a chip drawer under the mill to make clean up easier.  

As of now, I have all the MDF pieces cut out and almost all of them assembled.  I put a quick coat of paint on it before I fully assembled it while everything was easy to access.  This thing is already really heavy, so I might stick it on wheels so it can be moved once the mill is in it.  The back panel where the tool changer will go is 2 pieces so that one can be removed when I install the tool changer and then when I need to get to it to work on it.  The head will stick out the top a little bit, but that seems to be how all of them are.  I am going to relocate the control box on the side of the head to the electronics enclosure in the back.  I still need to figure out how to control the spindle directly from the computer.  

I also made a tool finger to test before I make more of them.  The machine cut it fine, but it is too tight on the tool.  I will need to make that fit a little bit looser.  I also changed the tool finger design so that it will have a spring and lever to hold the tool in place instead of just gravity.  This should keep the tools from sliding out if the machine is vibrating, if the tool changer spins too fast, or when it is being pushed into place and retracted. 

I solved 2 of my previous problems as well.  The tool height issue was user error.  When I set the tool off set or touched off, I did the correct T1 M6 to tell it which tool I have, but I didn't do G43 H1 to tell it to use that tools offset.  For the lost motion in the X, it was the stepper coupler being a little bit loose.  I was able to turn each of the screws in the coupler a full turn and a half so I am guessing it slipped a little bit when switching directions causing the axis to drift. 

Here are some pictures.


----------



## macardoso

shooter123456 said:


> I couldn't deal with the chips getting everywhere anymore, so I decided to put a short hold on the tool changer to get going on the enclosure.  I originally planned to try to do it with sheet metal, but after trying to make a small simple part without a brake and shears, I decided that just wasn't going to happen.  Looks like MDF is the material of choice.  I used it on my X2 enclosure and sealed with epoxy paint and that held up fine for a year until the PM25 came and that mill stopped being used.
> 
> I am not very good at working with MDF or wood, so this might end up being a bit of a hack job.  I plan to use plywood for the base and MDF for the body, acrylic for the windows and aluminum for the doors.  I am going to machine a 4 piece frame for each door and they will slide on drawer sliders I used on the X2.  I am hoping to just use the sliders on the top away from the chips and then something simple to support the doors on the bottom.  I ordered 2 LED floodlights to light it up inside and I am planning to make a fogbuster type coolant system to use for the coming months until I figure out how to handle the flood coolant.  I will need to do some waterproofing of the electronics before I can do that.  I plan to put a chip drawer under the mill to make clean up easier.
> 
> As of now, I have all the MDF pieces cut out and almost all of them assembled.  I put a quick coat of paint on it before I fully assembled it while everything was easy to access.  This thing is already really heavy, so I might stick it on wheels so it can be moved once the mill is in it.  The back panel where the tool changer will go is 2 pieces so that one can be removed when I install the tool changer and then when I need to get to it to work on it.  The head will stick out the top a little bit, but that seems to be how all of them are.  I am going to relocate the control box on the side of the head to the electronics enclosure in the back.  I still need to figure out how to control the spindle directly from the computer.
> 
> I also made a tool finger to test before I make more of them.  The machine cut it fine, but it is too tight on the tool.  I will need to make that fit a little bit looser.  I also changed the tool finger design so that it will have a spring and lever to hold the tool in place instead of just gravity.  This should keep the tools from sliding out if the machine is vibrating, if the tool changer spins too fast, or when it is being pushed into place and retracted.
> 
> I solved 2 of my previous problems as well.  The tool height issue was user error.  When I set the tool off set or touched off, I did the correct T1 M6 to tell it which tool I have, but I didn't do G43 H1 to tell it to use that tools offset.  For the lost motion in the X, it was the stepper coupler being a little bit loose.  I was able to turn each of the screws in the coupler a full turn and a half so I am guessing it slipped a little bit when switching directions causing the axis to drift.
> 
> Here are some pictures.




That's a nice looking enclosure.  Would you be willing to share plans for it?


----------



## shooter123456

macardoso said:


> That's a nice looking enclosure.  Would you be willing to share plans for it?


I could do that.  All I have is a 3D model, but if you have a way to view it, I would be happy to send it to you.  Message me your email address and I can send it right over.


----------



## shooter123456

I am just about done with the enclosure now.  It has the inside completely painted and waterproofed and the stand has the skeleton done.  Getting the enclosure up onto the stand was a bit of a challenge, but it got done.  I made the decision to put the machine into the enclosure before making the doors since they would make a ton of chips and I can mostly contain them even without doors.  The windows are going to be .093 acrylic sheets, and I am considering going with something a bit thicker for the doors just in case something gets flung like a broken tool or workpiece pulled loose.  That way, if it is thrown toward me, hopefully the doors will stop it.  I removed the spindle control box and it will be relocated to the electronics box on the back of the machine.  

I can control spindle on and off easily with the computer, but I have not yet figured out how to control speed.  Since I run it at full speed 95% of the time, for now I will just leave the pot with the box and walk around to the back of the machine to adjust the spindle speed.  I am waiting on a cable track for the head so I can wire it up nicely.  The track will carry the lines for the air cylinder, the spindle motor wires, and the mist coolant lines.  

Here are a few pictures.  Unfortunately, the glass on my camera is still broken (Just got a new one, need to get it installed!) so there is some flaring of the light.  

Empty enclosure.  There is about an inch of clearance on each side for the machine to get in.  I did this just because I don't have a way to cut the MDF accurately enough to make it closer.  I will use some rubber sheets to fill the area between.





Machine in place.  Getting the table in there wasn't easy, but hopefully I won't need to do it again for a while. 





Other side.





Here is the naked head.  There are lots of holes in it that I would like to fill somehow.  I will try to re use some of them to mount the coolant head, but I want to get rid of the rest.  I might fill them with body filler and repaint it. 





I am still looking for a new spindle motor, but so far that search hasn't yielded any good results.  I don't think it is worth it to spend $500 or so for a DMM servo as discussed a little earlier.  I have not been able to find an AC motor that would work either.  The ones I have found are 56C, which will not fit.  I was looking for some smaller motors, but I haven't found anything that looks suitable yet.  I am looking for something 1 to 2 HP, 3500 RPM or higher, less than 20 lbs, and hopefully $400 or less for the motor and control.  It seems like that is a tall order.  If anyone knows of a motor that would fit those points, that would be much appreciated.


----------



## phazertwo

Looking pretty good.  I am patiently waiting to see how your enclosure turns out...   I have been dreaming of a sweet enclosure, but also lack the equipment to make something nice out of sheet metal.

As far as a motor, why can't you use a 56C and just let the face be above the top of the mill?  As long as the shaft hangs down low enough.

PZ


----------



## shooter123456

phazertwo said:


> Looking pretty good.  I am patiently waiting to see how your enclosure turns out...   I have been dreaming of a sweet enclosure, but also lack the equipment to make something nice out of sheet metal.
> 
> As far as a motor, why can't you use a 56C and just let the face be above the top of the mill?  As long as the shaft hangs down low enough.
> 
> PZ


Its just one of those things... I could probably invest the time and money and make something really nice, but its a supporting accessory.  Something hacked together that looks rough and gets the job done faster and cheaper is fine by me in this case.  Now if I bought the mill because I wanted to have a show piece I could be proud of, that would be a different story.  But in the end, I want to spend that time and money making parts and adding stuff to the machine.

Referring to the motor, when I imported a 56C model from one of the manufacturers, there was not enough room between the air cylinder and column for the motor to go.  With it just clearing the air cylinder, it overhung the back of the head and interfered with the Z axis stepper.  The other option was to off set it to the side, but that would require either using 2 belts to route under the air cylinder or redesigning the air cylinder to make it work.  Neither of those seemed like ideal solutions if there are smaller motors available.  On top of that, the motors I was looking at were 26 lbs, compared to less than 10 for the current motor or some of the servo options.  I would like to try to keep the weight of the head down so it can move quickly.


----------



## shooter123456

In hopes of figuring out who makes the spindle motor and finding more details about it, I took the sucker apart.  In the end, I have learned nothing.

It is a 2500 rpm Nema 34 750w brushless motor, it has a small fan under the top cover, with 8 wires. 5 appear to be for feedback, 3 for power.  The feedback wires are marked +, -, W, U, V. The 3 larger wires did not have any visible markings.

The only markings on the circuit board inside the motor are:
L3155-HL
13/3/23
H13938
P46S24027

Unfortunately, google did not yield any results that give me relevant information.  I had asked Matt for some more information about the motor and control board and he wasn't able to provide anything for me.  

If you have ever wondered what these things look like on the inside, here are some pictures.

Top cover off.  You can see the weird fan on the top.





Side view with wire cover removed.  It looks like this thing melted at some point.  It may have been to seal the motor or support the wires, but it no longer does so. 





Fan removed.  It is just pressed onto the back of the shaft.  I am not sure how it works with the blades not having much room for air flow, but it might be to draw air over the fins on the outside of the motor.





Rear panel removed giving me a decent view of the encoder inside and rear bearing.  You can also see the cooling fins pretty well here.





Here it is next to the 1000 oz in nema 34 that will be going on the Z axis at some point.  The spindle motor is slightly longer, but the same face size I think.





Closer view of encoder and power wires.  Soldering doesn't look all that clean.





Shaft removed.  The magnets are in the shaft and the coils are in the motor body.  Backwards from a brushed motor as far as I know.





Picture of the shaft.  The magnets in this thing are rediculously strong.  It took some care to get it back in the motor without crushing my fingers or breaking the encoder.





That's all for now.  If anyone can tell me anything about the motor, that would be great.  I may repurpose it once I pick a new motor for the machine.  Maybe to keep costs low, I will swap the motor with the one on my lathe.  The lathe has a 4000 RPM 750w brushed motor.  That should give me the higher speeds I want, about 8800 RPM with my current pulley set up.  The 2500 RPM motor would change the lathe low speed from 50-1000 to 30-625.  That would give the lathe a ton more torque and the mill would get the speed I want.  Decisions decisions.


----------



## shooter123456

The enclosure is about set now except for the doors.  The windows have been installed, they are just .093" acrylic sheet and have 6 holes drilled, then 6 matching holes are drilled into the MDF and screws and nuts are used to secure it in place.  I made a few parts with the machine and even without doors, I am containing well over 90% of the chips.  There are only a few cuts in a few directions that manage to send chips out the front of the enclosure.  I got my LEDs installed and that makes a huge difference.  They are cheap ebay units, they cost $10 for the 2 of them. They are wired directly into an AC line and come on when the machine is powered up.  

I had an issue with the Z axis driver cutting out and dropping the head, which obviously is not what you want when you are spinning a cutter... I lost a part to that and I am not 100% sure why it happened.  The drive wasn't hot, but after leaving the machine off overnight and running it with an extra fan blowing on the electronics, the machine cut for probably 6 hours (spindle time, probably 10 hours total on time) with no problem.  

For the spindle draw bar, I wired a button into the box where the chip guard interrupt was.  I simply took that out, shorted it so that it assumes the chip guard is always closed, then the hole was the perfect size for a button I had on hand.  Just wired it in to the solenoid and now when you press the button, the tool releases, release the button and the tool is secured.  I forgot to take a picture of that, but you can see it easily in a few of the other pictures I have.  

I am going to need to come up with a better work holding solution, because the vise I have isn't ideal.  Using the vise, the max usable Y axis travel is a little over 4".  In one direction, the vise runs into the way covers, and in the other direction it leaves 2" unreachable past the front jaw.  I am considering either trying to find a vise that doesn't stick out as much in the front or making something suitable instead.  There are other methods of workholding, but a simple and effective one that cuts your travels by 40% isn't ideal.  

I finished making an encoder mount to give the controller some feedback and hopefully increase the reliability a little bit.  I know a lot of people aren't fans of encoders since "properly designed" stepper systems shouldn't need them, but I am not an expert, and this system is far from properly designed.  $30 for 3 encoders and a few hours of machine time to prevent lost parts due to stalls, drives overheating, etc is worth it for me. 

Up next is some pulleys for the steppers and encoders, some motor covers, making the doors, a control panel, and continuing on the ATC.  I have some of the parts machined already, now I need to figure out the air cylinder for it and the sensors.  I got an inexpensive 7" usb monitor that I think should suffice for the control panel, along with some buttons and switches.  I was looking into a motion controller for the machine, but I wasn't able to find one that would run linuxcnc for a decent price.  Instead, I may just try to replace the control computer with something a little better.

Here are the LEDs I got.  They are 10w each and are plenty bright. 






It makes it nice and bright inside.  In this picture you can see the button on the side of the head for actuating the drawbar.





Here is a side view through the window. There is some glare off the LED and the cracked camera glass, but you get the idea.  The wiring needs to be cleaned up, but in due time.  I plan to fix all of that when I make a new electronics box (Not enough room in the current one) and control panel.  Here you can also see the drawbar button. The wires and hoses will need to be run through the cable track once I figure out how I want to mount it. 





Here is the little USB monitor.  It is only 7", but as you can see that is plenty to see linuxcncs interface.





Here it is working on the encoder mount.  It is using a 5/8" 2 flute indexible carbide endmill in a homemade holder.  Everything is much easier to see with the lights.





Here that part is after finishing everything but the backside.  It is looking pretty good for the most part.  There were some issues with chatter doing the corners during a finishing pass and there were some marks left by imperfect backlash compensation. 





Shiny.





Backside.





Using super glue work holding for this part.  It needs just about every inch of the 7" of travel the machine has (actually more like 6.8" due to an error on my end).  The stock is 6.5" long.  The first part will be done on the mill, then I will mount it on the lathe to cut the outsides down to size.





I need to work on my Fusion skills, because every program fusion gives to run, something like 30% to 50% of the time it spends just moving around and not cutting anything.  On this program, it was 45 minutes in total, and 15 of those, it was just walking around doing random whisper cuts. 





Lotsa parts getting made.  Some of them need some work on the backside done, but it is coming along.  There is some corrosion on a few of the parts because I get my material from a recycling center and sometimes they sit outside for a while before I can rescue them.  The discoloration usually comes right off with some sandpaper.


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## shooter123456

I ran into a snag with the enclosure doors, as tends to be the case.  I was planning to re-use the draw slides from my old enclosure for the doors.  Unfortunately, they are 18" long, and my smaller door is 14" long.  That limits its opening by about half, which isn't going to do.  I also didn't plan through how to account for the metal bending after machining, and there is a bit of twist in the door frames.  I think I can force it to be relatively straight if I have stronger rails on the top and bottom.  Also, I cut the long pieces I needed for the doors out of a big plate on the mill, and that took forever.  I should have just ordered the stock in the size I needed and saved the time (at 5x the cost though...)

So right now I am trying to come up with new ideas for mounting the doors.  I could try using some cheap round linear rails on the top and bottom, but I may run into space issues, since I didn't build enough in between the Y axis motor and the doors.  I think I can slide the whole machine back a little bit to make room.  I could also try some aluminum angle stock and make some plastic blocks to slide on those.  It won't be as smooth, but I think it would be effective.  Another option might be using some skate bearings and making some guide rails using an arrangement similar to how a bandsaw guides its blade. 

I have a line on a new spindle motor that I am really excited for.  It isn't final yet, but I may be getting a 2 HP 6000 RPM motor for it, and I will bump the speed up to about 7500.  If that works out, I am looking into adding an encoder to the current motor and getting a servo drive to use that on a 4th axis/lathe attachment.  That would be much better than making 2 4th axis attachments, one with a stepper for indexing and 4th axis cutting, and one with a BLDC for lathe work.  If I can't make the spindle motor a servo, I might just forgo a true 4th axis, and instead do what Tormach does with their Rapidturn and have a motor + indexing plate.  

Here is how I cut off the stock for the doors.





Then they were held like this to cut them to size and such.  I spent probably 15 hours with the spindle running to make the 8 brackets.  There must have been better ways, but I made tons of chips and the machine ran well, so it works for me.  Also, you can really see the button here.  It is almost like that part was made for a power draw bar button.





I didn't take a picture of the finished parts because I wanted to solve the mounting problem first.  They are going to need some clean up and a coat of paint though.

I also turned the tool platter on the lathe to remove all the excess material.  That part is done now, which I figured would be the most difficult of all the tool changer parts.  I have started on the air cylinder for it and I am waiting on stock for the tool fingers.





I could have sworn I took a better picture once this was done, but I don't have it now (anyone else have a galaxy S8+ that has disappearing images?) This is the best I have at the moment.





The machine is coming along!  Working out issues as I go seems to be working, and each little upgrade makes the machine (and me) much more productive.  Hopefully that continues until it is making parts faster than I can keep up.


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## shooter123456

Also, I figured it was time to update the total costs so far.  I am adding this info since I rarely see it about others machines which makes it hard to tell what you will spend to get a certain result.  Hopefully this way, if someone else is researching the way I was and trying to figure out what it will cost for a machine like this, they will see this and get a much clearer idea.  If it isn't useful to anyone else, at the very least, it can help keep me organized in case something breaks and I can't remember what it was when I go to replace it.  If anyone wants links to the parts I used and where I got them, let me know.

I figured I would break it down by area so it isn't one huge list.  All costs include shipping.

General Machine Parts:
PM-25 mill - $1649
4 inch mill vise - $100
4 TTS holders +1 ER20 collet - $126
6 TTS knock offs (non atc collar) - $90
5 Homemade TTS holders - $30
Total: $1995

CNC Conversion Parts:
2 400 oz in Nema 23 steppers - $67
1 1000 oz in Nema 34 stepper - $69.79
2 DM542T stepper drivers - $67.90
1 DM860T stepper driver - $53.95
1 550 mm SFU1605 ballscrew - $65
1 750mm DFU1605 ballscrew - $0 (Details below)
1 350mm DFU1605 ballscrew - $0 (Details below)
6 7001 AC bearings - $15.54
3 flexible couplers - $15
350 watt power supply - $30
240 watt power supply - $20
Break out board - $10
Aluminum stock - $10
Total: $424.18

Enclosure:
2 48x96x.75 MDF Sheets - $72
5 2x4s - $15
1 box of screws - $9
3 Acrylic Sheets - $36
2 can of Epoxy Paint - $30
2x 10 watt LEDs - $11
Total: $173

Automatic Tool Changer:
Air Cylinder Stock - $50
Air Cylinder Seals - $20
Air Cylinder Connectors - $5
5 Way Pneumatic Solenoid - $20
Fasteners - $30
400 oz in Nema 23 - $33
6205 Ball Bearing - $3.11
Linear Guides and Bearings - $34
Aluminum stock - $25
Total: $220.11

Grand Total - $2812.29


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## shooter123456

I realized I mentioned I would document the deal with the ballscrews, then forgot and never did.  

I ordered a pair of double nut ballscrews from linearmotionbearings2008 on ebay.  I was quoted $100 for the 2 screws and 2 double nuts, shipped to me, machined to my specifications.  I knew that price was low, but others had reported good experiences and received a good product, so I said what the hell, and took a shot.  They were made and shipped, I received them about 2 weeks after I placed the order.  First thing that was a problem was the packaging.  It was packaged in a flimsy cardboard box, and the ballscrews were wrapped in bubble wrap.  There was nothing to protect them from being bent. 

The second problem was pretty obvious from the picture below.





He had sent single nuts, not double nuts.  Oh well, it happens.  I contacted him and he apologized and sent a pair of double nuts the same day.  I received those about a week later.  In the mean time, I inspected the screws.  They were indeed not straight, with the long one being much worse than the short one. The actual bend wasn't so bad, it was probably around .05" for the long one, and .03" for the short one.  The real issue was the end machining.  First, none of my stuff fit.  The bearing journals were oversized (by about .01") so it took a lot of sanding to get the bearings to fit.  That is where I found just how straight the end machining was.  When I chucked it up in the lathe, holding one end in the 3 jaw and the other end in the steady, while both ends had runout less than .005", the middle was wiggling at .375", if not .5".  It was way off.

Then the double nuts came.  
The first thing I saw was the grinding job done to make the screws and keys sit flush.  Looks like someone just put them together and used a bench grinder to grind it flat.  In the process, taking the head off the screw making it very difficult to remove.  When I tried to thread them onto the screws, neither one would thread past the first nut.










Removing the screws was rather difficult, because they were soft, and had almost no head left. I eventually did get them removed and put them on the ballscrews.  Then it was pretty clear why I couldn't get it to thread on.  With the keys removed, this is where the two nuts met, with no pressure added.





Taken apart all the way for further inspection found that the key ways were not milled straight and they weren't on center. The faces that met each other also were not ground, and there were some nasty burrs.  Both were also full of grinder dust.





A closer look at the screws showed some of the threads were stripped out.  I got some replacements which showed that 3 of the 4 holes were not tapped straight.





All of these issues meant the screws and nuts were basically unusable without significant work.  

I told the seller about my concerns, and the response was very unprofessional.  I won't go into detail, but he said that was the first complaint, these screws and nuts are actually very high quality, the double nuts are precision adjusted for backlash under .0006", and he has already lost money on the transaction because he had to send the double nuts that they messed up the first time.  After some back and forth, he tried to get me to send them back to him on my dime, I refused because that cost was huge, and it was their problem to fix.  Then they offered to remake the screws if I paid the $46 shipping, I again refused stating that I did not want to pay extra to get what I was promised the first time.  Then they offered a full refund asking me to ship them back if the cost isn't too great so they can check them and try to improve.  The cheapest quote I got for the slowest shipping option was $296.  I have no idea how he was shipping them here so cheap, but I did not send them back.  

It took a lot of work trying to get the preload set somewhat well, but these screws are still very rough and because of the bend and poor end machining, there is some oscillation as the axis moves.  As a note, the nuts and screws were significantly lower quality than the ones I got for the X2, and even after I spent a lot of time trying to get them preloaded, the backlash is still about the same as with single nuts.  So I am using these screws for now while I look for replacements.  I check ebay often looking for some ground options I can afford.  Some have come up that are close, but nothing is just right.


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## macardoso

shooter123456 said:


> I realized I mentioned I would document the deal with the ballscrews, then forgot and never did.



Sorry to hear about your experiences. I originally purchased Roton screws, but wasn't the most pleased with the backlash and lead error (although the screw and nut quality was quite good). Really this isn't their fault as they are commercial "transport" grade screws, not precision ground units.  I had looked at your supplier for screws and was still actively considering them, however based on your experiences I may pass them over.  Unfortunately there aren't many offerings for low cost precision screws for us hobbyists.


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## shooter123456

macardoso said:


> Sorry to hear about your experiences. I originally purchased Roton screws, but wasn't the most pleased with the backlash and lead error (although the screw and nut quality was quite good). Really this isn't their fault as they are commercial "transport" grade screws, not precision ground units.  I had looked at your supplier for screws and was still actively considering them, however based on your experiences I may pass them over.  Unfortunately there aren't many offerings for low cost precision screws for us hobbyists.


Given the price I was quoted, I went in expecting them to be crap, hoping they would surprise me.  They did not surprise me though so I got a decent deal and some day, I might try to fix them.  I have thought about pressing a sleeve onto the bearing journal and threads that are off, then trying to machine it in line with the ball races and stepping up to the next size AC bearings.  At the very least, I don't think I could make it any worse. 

You are right about the screws.  The options are few and far between unfortunately. I found another place that sells ballscrews that look a lot nicer, but they are priced accordingly.  Anahiem automation is the site, and they have 1605 and 1610 DFU screws available for $236 for 1000mm max length screws.  But they are still rolled and C7 accuracy.  As soon as you step up to ground, the cheapest I have found start around $485 each.  For 3 axes, that costs almost as much as the entire mill, which just doesn't make sense.


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## macardoso

shooter123456 said:


> Anahiem automation is the site



I've looked at their products and have been impressed. They seem to have quality products at less-than-industry prices, but still higher than a hobby machine deserves. Another thought would be to work with Automation Technologies to get the screws you need. I'm pretty sure they come from the same place as your screws, but as a US based company, you can probably have a little more luck with making sure your screws come straight and concentric. Worth a call at least.


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## GunsOfNavarone

shooter123456 said:


> I have had the chance to play with the mill a bit more and get started on the CNC parts.  I forgot just how much fun it was turning handles and how fast simple operations can be.
> 
> I modeled up the conversion parts I will be using.  I am going to need to make 15 total parts.  I am currently shopping for a new X axis ballscrew with double nuts and a nema 34 for the Z axis.
> View attachment 256296
> 
> 
> The machine is very capable and leaves a very nice finish in aluminum.  It has been able to hold .001" without much effort on my part.  If I tried a little harder, it would certainly do better.
> View attachment 256297
> 
> 
> A couple of weird things I have experienced so far:
> 1. When I lock the X axis gibs, the Y axis tightens up and becomes harder to turn.  The only thing I can think of that would cause that is the saddle distorting when the gibs are tightened.
> 2. There is a point on the X axis where it starts chattering a bit in deep cuts.  It is only about half an inch that it happens so I figure it must be something with the leadscrew, or maybe a low spot in the ways.
> 3. There is a slight delay from the spindle motor when you start a cut.  When the cut starts, it pauses for maybe half a second while the RPMs drop, then it jacks up the torque and gets the spindle back up to speed.  It takes way longer for this motor to respond than the brushed motors I have used.


hey shooter, now that you have many pounds under your belt on the pm-25, do you have any regrets not going with the PM-727? I am right on the edge of ordering the 727 (my first mill) but is the 25 capable enough? I assume that since you purchased it to immediately upgrade it to CNC, ( and your parts look great!) The 25 must be a pretty strong contender for a first mill?


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## shooter123456

GunsOfNavarone said:


> hey shooter, now that you have many pounds under your belt on the pm-25, do you have any regrets not going with the PM-727? I am right on the edge of ordering the 727 (my first mill) but is the 25 capable enough? I assume that since you purchased it to immediately upgrade it to CNC, ( and your parts look great!) The 25 must be a pretty strong contender for a first mill?



When I was looking at a new mill, the PM-727M was also one that I considered.  For me, the PM-25 won for a few reasons.  
1. Factory belt drive with the spindle going to 2500 RPM.  The PM-727M uses gears and a single speed motor, which meant it would be a little less flexible, and speeding up the spindle would take a lot more work.  The PM-727V has a 1.5 HP BLDC motor, but still had the gear head and was $600 more than the PM-25.  Bumping up the PM-25 spindle only required making 2 new pulleys.  The 727 would probably need to have the head taken apart, the gears removed, potentially draining the oil, then redesigning the motor mount, maybe replacing the motor (not sure if it can be run variably with a VFD), buying a VFD to get variable speeds, then making the new parts.  Just a lot more work. 
2. The extra X axis travel.  The PM-727M and the PM-25 have the same table (I think, not 100% sure, but same size) but the PM-25 has 20.5" X travel while the PM-727M has only 15:.  This means that the 727 will have a stronger table since the saddle is longer and supports an additional 5.5", but having only 1 milling machine, that extra travel was worth the loss in strength.
3. Being similar to the G0704 meant that there would be more info related to the CNC conversion out there.  That meant less design work from scratch for me. 

While I don't doubt that the 727 is a stronger and more capable machine, I don't regret my choice at all.  The PM-25 is more flexible (and I mean that like being adaptable, not flexible like flimsy) in my opinion which is what I needed.  I can say for sure that the machine is strong and capable, and very well made.  So far, the limiting factor in terms of heavy cuts has been the spindle motor.  It usually starts struggling before rigidity in the machine becomes a problem.  So far, the heaviest cut I have taken is 1.25" wide, .05" deep, at 52 IPM.  It was with my 2" 4 flute face mill, which gave me an MRR of 3.25 in^3/min.  I think the motor still had some strength left, but the belt started slipping when I went higher.  

I hope that helps make your decision!  If you have any specific questions, I would be more than happy to try to answer them.


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## macardoso

GunsOfNavarone said:


> hey shooter, now that you have many pounds under your belt on the pm-25, do you have any regrets not going with the PM-727? I am right on the edge of ordering the 727 (my first mill) but is the 25 capable enough? I assume that since you purchased it to immediately upgrade it to CNC, ( and your parts look great!) The 25 must be a pretty strong contender for a first mill?



I also wrestled with the mill size question. I purchased my G0704 from Grizzly when I was just starting out in the hobby and had outgrown my Sherline "mini mill" (micro).  The machine out of the box was really quite nice, and I did eventually CNC it because it was a fun project.  Today, (5 years later) I am feeling like I am just running out of space and power on the machine.  I would love a larger machine (RF45 or larger) and will probably upgrade. That being said, I think it all about the kind of parts you want to make, how much you want to spend, and how capable you are to design your own CNC conversion (if you choose to do so).  

I will say that the extra 1.5" of Y travel on the 727 would go a long way as that is where I am the most limited on the G0704. I rarely need the full 18" of travel in X.  The 727 also weighs quite a bit more would would likely lead to better rigidity (the biggest issue with all <2000lb machines).  In the end, you will have a great time with either machine, just understand everything will have its limitations.


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## GunsOfNavarone

macardoso said:


> I also wrestled with the mill size question. I purchased my G0704 from Grizzly when I was just starting out in the hobby and had outgrown my Sherline "mini mill" (micro).  The machine out of the box was really quite nice, and I did eventually CNC it because it was a fun project.  Today, (5 years later) I am feeling like I am just running out of space and power on the machine.  I would love a larger machine (RF45 or larger) and will probably upgrade. That being said, I think it all about the kind of parts you want to make, how much you want to spend, and how capable you are to design your own CNC conversion (if you choose to do so).
> 
> I will say that the extra 1.5" of Y travel on the 727 would go a long way as that is where I am the most limited on the G0704. I rarely need the full 18" of travel in X.  The 727 also weighs quite a bit more would would likely lead to better rigidity (the biggest issue with all <2000lb machines).  In the end, you will have a great time with either machine, just understand everything will have its limitations.


That really leans me towards 727 again. All good points as well. I would love CNC, but the expense! I wouldn’t even know what software to control it. It would have to be a premade kit as I don’t think I have the attention span to wing that over months. I have seen kits for $2500 and up, right now that sounds crazy, one day I know I’ll be chomping at that bit. Is the 727 just out of the question for CNC?
Thanks everyone for the help, my apologies if I hijacked this thread...


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## macardoso

GunsOfNavarone said:


> one day I know I’ll be chomping at that bit. Is the 727 just out of the question for CNC?



So take anything I say with the understanding that I have done a few CNC conversions and feel pretty comfortable with the process. Basically all hobby CNC conversions are: design a few motor mounts/bearing blocks, machine ballscrews, hook up motors to control electronics, and plug into a PC.  You can take it to any extreme that you want but you could probably do the whole thing for <$1000 on a budget.  You will need some design abilities, machining capabilities (you can use your shiny new mill to make most of the parts, but if you need to modify the machine itself, then you need another tool), and comfort with basic wiring. The big question is, do you really need it?  Many of the components I make actually could be done on a manual machine in less time than writing a program or jogging the machine. But there are certainly others which absolutely need CNC to be made.  

My thoughts in short, think what kind of work you want to do on it (a manual machine is very capable by itself). If you want a CNC, and are comfortable designing and making your own conversion, either mill works fine. If you will enjoy the building of the CNC then it can be a ton of fun to do just that (and save money), but if you need to have a machine working as fast as possible, buying a kit accomplishes that.


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## GunsOfNavarone

You know, that brings up a really good question and I have been pondering for weeks.....haven't gotten up the nerve to ask yet. What if you need to mill something let's say 5/8" thick and let's say at one end it comes to a taper. That is,  say the Y measurement is 3" but tapers down slowly, at a 4 5 degree angle to  1/2" along the Y. This requires the X and Y to be turned at a specific ratio to one another. How would you do this w/o CNC....this is why I KNOW I will need CNC....unless there is a common way to do this that I am unaware because.....well, I haven't learned that among many things right now.


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## macardoso

GunsOfNavarone said:


> How would you do this w/o CNC



Use a swivel milling vise.  Set the vise at 90* square, mill your one side, the loosen the vise, set to whatever degree your wedge requires, then cut the second side.   Gets tricky, but there were probably a hundred years of people machining stuff w/o cnc.


The other way (if the part can’t be held in a vise) is to clamp it to your mill table with hold down clamps and use an indicator to set the angle.   Basically you do some trig to say that over a distance of 4” you should have a change in Y of something.   Use the handwheels and a test indicator to measure where you are at and tap it into alignment with a mallet. Tedious but perfectly doable.


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## GunsOfNavarone

Yeah, I thought that about life before CNC, the “old timers” probably did this without batting an eye. Your first technique sound doable, the 2nd sounds tricky as hell!


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## shooter123456

I recorded the machine making a few cuts.  Most of them are pretty light, but it should give you an idea how it is running.


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## macardoso

Looking great!  What spindle motor are you running right now?


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## shooter123456

macardoso said:


> Looking great!  What spindle motor are you running right now?


Thank you! Currently the stock 1 HP BLDC motor.


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## mksj

Nice conversion on the PM-25, your saga with the ball screws is similar to others posted experiences with the least expensive options.  There are some reputable sources from China, usually a bit more cost but sometimes spending a bit more, one ends up with not having unusable products. What always is shocking to me is that you can buy these parts from China have them shipped to you for far less than just the cost of shipping it back to China if there is an issue. I am glad at least you got a refund. On some items, Chinese sellers just send you a new part because of the cost of returning the item. The positive side of buying through say eBay is at least you have some recourse if the product is defective or not as described. I pretty much have stopped buying anything direct from China because of the issues mentioned, along with long delivery times and very poor packing which often results damaged parts.

There needs to be some consideration if CNC conversion is a dream that it would be nice, vs. buying a mill with the intent to convert to CNC. Also the scope and type of work, along with the build budget. Almost every CNC conversion with smaller mills, individuals will mention that it would be nice to have more travel. When one looks at the machine footprint/floor space, once you build an enclosed cabinet, there might be 25% difference between what you would need for say a PM-25 vs. PM-932. Just mentioning this, because table travel becomes a significant factor. If your intent is to mill,  then the PM-927MV would be a good choice with limited floor space, if your intent is to do a CNC conversion down the line, the PM-30MV would be my first choice due to the increased travel and 2Hp motor vs. the PM-25MV.


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## shooter123456

GunsOfNavarone said:


> That really leans me towards 727 again. All good points as well. I would love CNC, but the expense! I wouldn’t even know what software to control it. It would have to be a premade kit as I don’t think I have the attention span to wing that over months. I have seen kits for $2500 and up, right now that sounds crazy, one day I know I’ll be chomping at that bit. Is the 727 just out of the question for CNC?
> Thanks everyone for the help, my apologies if I hijacked this thread...



Everything is a trade off, you just need to decide what you can live with trading away and what you really need.  I have converted 2 machines to CNC and sort of built a CNC lathe from scratch (its mostly done, just back burnered for now) and you really can do it for as much or as little as you want.  I don't think I would ever spend $2500 on a conversion kit, that just seems silly to me.  Some motors, electronics, and ballscrews is really all you need to get it going.  I typically upgrade along the way as is needed, but a lot of the cheap stuff I get at first has never needed to be upgraded.  I prefer to make mounts just because they are so simple and easy to do.  

The 727 is absolutely not out of the question for CNC.  There were just a few specific things I wanted that the 727 would have been more difficult and expensive to accomplish.  Mainly related to the spindle and spindle motor.  I have no doubt that the 727 would make a fine CNC mill.

Also, you didn't hijack the thread.  This is right on topic in my opinion.


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## macardoso

shooter123456 said:


> Thank you! Currently the stock 1 HP BLDC motor




I'm impressed! You can certainly hear it bog down at the start of the cut, but it really moves some material.  I'm excited to see how your ATC turns out! We might have to exchange notes!


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## shooter123456

macardoso said:


> I'm impressed! You can certainly hear it bog down at the start of the cut, but it really moves some material.  I'm excited to see how your ATC turns out! We might have to exchange notes!


I appreciate that! The spindle motor does seem very slow to react when a load is applied, and I noticed that even before it was CNCd.  Taking manual cuts with the motor pulleyed in its stock configuration, it would still take a second to ramp up the torque.  I am hoping that the new motor solves those problems.  I know that the currently spindle isn't straining with those light cuts though.  Most of them were under .25 WOC, .05 DOC, and 35 IPM which is only .4375 in^3/min.  It managed 1.25" WOC, .05" DOC, at 52 IPM which is 3.1875 in^3/min which is 7x the cut.  After that the belt slipped, but the motor was still pushing.  

Hopefully I can get the ATC up and running soon!  Besides the tool fingers (3 parts for each of the 10 fingers...) I only have 6 more parts to make.  We should exchange notes for sure.  I will have a few questions about the programming, since I think you mentioned you already did that part.


----------



## macardoso

shooter123456 said:


> I will have a few questions about the programming, since I think you mentioned you already did that part.




I think the motor bogging down has more to do with the control electronics than the motor horsepower. It takes the slow control loops in the stock motor electronics a bit of time to "catch up" when a load is applied. Not sure there is much to be done about that. 

The software to control the ATC isn't too bad.  Are you running Mach 3?


----------



## shooter123456

macardoso said:


> I think the motor bogging down has more to do with the control electronics than the motor horsepower. It takes the slow control loops in the stock motor electronics a bit of time to "catch up" when a load is applied. Not sure there is much to be done about that.
> 
> The software to control the ATC isn't too bad.  Are you running Mach 3?


I agree completely.  The new spindle motor is a servo, so in theory it should catch up faster.

I am using linuxcnc.


----------



## macardoso

shooter123456 said:


> I am using linuxcnc.



 I did my ATC with Mach, so the configuration won't match, but the concepts should be the same.  I wish there was a well documented, feature filled, and stable machine control software for us hobbyists.


----------



## GunsOfNavarone

Man! The last few post here i had to read twice each...thought I was reading typo's, come to find out I'm just stupid on this subject. That video, I could watch that for a very long time....mesmerizing...
Well, I will definitely be hitting you up for some help when the time comes, great work there brother!


----------



## phazertwo

shooter123456 said:


> I recorded the machine making a few cuts.  Most of them are pretty light, but it should give you an idea how it is running.



Just watched your video.  Good looking stuff you got going on there.  Who's cutter is that 5/8 2 insert endmill?

Have you tried turning up your non engaged speed when running an adaptive tool path?  It almost looks like you're cutting faster than the linking moves.

PZ


----------



## shooter123456

phazertwo said:


> Just watched your video.  Good looking stuff you got going on there.  Who's cutter is that 5/8 2 insert endmill?
> 
> Have you tried turning up your non engaged speed when running an adaptive tool path?  It almost looks like you're cutting faster than the linking moves.
> 
> PZ


I usually bump it up to 80-100, but it looks like for that one, I left it at 35, the same as the cutting feed rate.  I agree though, it does look like it is cutting faster. 

The end mill is made by Zenit and uses ACMT inserts.  I think I have ACGT inserts in it at the moment.  I got a deal on ebay for a .375" single flute, a .5" single flute, a .625" 2 flute, and a .75" 3 flute, plus 40ish inserts for it for $50.


----------



## shooter123456

I got around to working up a mist coolant system out of an older RO filter I had around from fish tanks.  I only needed a few extra parts to get it going.  That included 1 connector, a block to mount everything to, 2 pressure regulators, a solenoid valve, a needle valve, and a locline kit from ebay.

It works the same as any other fogless mister where there is pressure on the air line and the coolant line, then they come together in a block with a needle valve on the coolant line.  I adjust the pressure on the two independently, then adjust the needle valve until I get a decent amount of coolant in the stream without fog.  The machine will control the coolant using the solenoid valve, and the locline will let me redirect it anywhere I want.  

The coolant tank is one of the filter bodies and I put a piece of copper pipe on the output line with an aluminum adapter.  This way, the input puts pressure on the air on top, which forces the coolant down, through the copper pipe, and out to the machine.  

I haen't had a chance to test it on the machine, but off the machine and using water, I was able to get good coolant flow with very little sputtering and very little fog.

Here are all the extra parts I had from taking apart the RO filter along with the 2 pressure regulators.






Here is the adaptor that fits the copper pipe into the filter body.





Here it was with the copper pipe forced through it.





Then I made this little block out of aluminum and that connector you see on top for the air line.  This screws into an existing hole whos original function I have yet to determine...





At the very least, this means I will not need to sit there with the air gun spraying out at is interpolates holes.  Hopefully, with coolant it will be able to run reliably without me keeping an eye on it.


----------



## phazertwo

Looks good, and way nicer than my setup!  Again, good work!

PZ


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## shooter123456

phazertwo said:


> Looks good, and way nicer than my setup!  Again, good work!
> 
> PZ


I appreciate it! Funny that you mention that, I was actually mimicking your mist system, and your post where you said 

"I like to pretend I'm a tough guy, but let me tell you... I giggled like a 3rd grade school girl at a sleep over... for the ENTIRE TIME it was cutting. Watching the mill chew up that material with out me needing to do ANYTHING but watch, freakin' amazing. Mist coolant is THE BOMB! "

is what made me say "Ef it, I need to get a mister set up!"


----------



## shooter123456

I ran into a bit of snag with the ATC.  I had a plan to machine the fingers that would minimize set up time and hopefully get me an accurate part.  The critical part is the thickness of the area that needs to fit into the groove of the tool holder, and the distance from the top of the finger, to the top of the groove.  It needs to be repeatable so that when the head lowers down to grab the tool, it can go to the same position each time and have the spindle face contact the tool holder shoulder. 

The plan was:
1. Cut the 2"x.25" stock to length in the band saw.
2. Use a simple program to drill the 2 .25" holes in the mill while leaving extra space for error.
3. Make a fixture to hold them 2 at a time using the .25" holes to locate them and 2 screws to hold them down.
4. Face the fixture and use that height as the zero reference.
5. Machine the fingers 2 at a time.

Well something didn't work.

I designed the holders to have fingers that are .085" thick to fit into the .09" grooves on a TTS holder and leave a little room for error.  I ran the first two, and that thickness came to .103 with a .013" tab left on the bottom of the holders.  I measured the bare stock at .252 in most places and .255 at the worst area.  I adjusted the zero height for the Z to bring it down .013" (.013" + .005" = the .018" they were over).  Ran the next 2, and this time, they came out to .065".  Weird, adjusting the height down .013" changed it .038".  I tried adjusting the zero again to bring it up .02" and the next 2 came to .059".  

So something is wrong with the Z axis losing steps somehow.  I think it could be the motor struggling some places and losing steps when the head rapids up.  It could also be something with the computer, but I would think if it was a latency issue, the X and Y would have problems too, since they move way more than the head does.  It could also be that the ballscrew end supports are loosening up, the coupler to the motor, or maybe some stickiness in the ways.  I will need to isolate this issue before I try again to make the fingers.  Luckily, I ordered enough stock to make 24 fingers, and I only need 10.  

I think finally putting the big 1000 oz in motor I have waiting on the Z will fix any issues with a lack of torque, and I need the current motor to rotate the tool changer, so that may be the next project.  I need to make an adaptor plate and open up the coupler from .25" to .5".  

The new spindle motor needs 240 volts (I got the go ahead to steal the line that runs to the hot tub) so it might make sense to plan to replace the 2 motors at the same time so I only need to deal with the wiring and such one time.  

Here is the fixture.






The drilled finger blanks.





Mounted in the fixture.





After machining.  These aint gon work.





I keep getting ahead of myself and forgetting about other stuff that really needs to be done before I should be working on the ATC.  This includes:
1. Way oilers and ballscrew greases.  I don't think I will get an automatic unit, but I would like to plumb everything so I can get to it easily to add the oil.  
2. X and Y motor covers.  I have some plans made up for these, hopefully keeping the chips out of the motor coupling and the ballscrew bearings.
3. Straighten ballscrews, remachine the ends square, make new spacers, and machine the mating surfaces.  I have some ideas for getting the ballscrews working a little better.  I also have some cheap linear scales I could try ballscrew error mapping with after.
4. New electronics enclosure.  I am out of room in my current box, and I need to add more.  I need to add the stepper driver for the ATC, the servo drive for the new spindle motor, another power line to get the 240 VAC to the servo drive, some connectors and fans.  In NC summers, it can get hard to keep the electronics cool.  Right now I have the door off completely and a box fan blowing straight at it.  This isn't ideal since it will blow chips right into the electronics if the chips escape. 
5. I need to finish making all my tool holders.  

So there is a lot to be done to say the least.  I am not completely sure at what point I will throw in the hat and say that's enough, but each improvement makes the machine run better and I am enjoying that so I will keep improving.


----------



## shooter123456

More parts, more progress, more problems!

I have been itching for some of those Mitee Bites Talon grips since I saw them on NYCCNC and how they securely hold the part using only .06".  Unfortunately, for 2 jaws and 4 grips, it is about $200.  They are relatively simple parts, so I made some. The jaws were very easy, made from aluminum and should last a very long time with the use my machine sees.  The grips are scrap yard mystery steel, probably 1018 or A36.  It machined nicely and didn't warp at all when I cut it down to size, so that makes me think hot roll.  I started with 7 clamp blanks, then lost once since I drilled the center hole off center, and then one more was pulled from the jaws and marred up when I was cutting them to length.  I ended up with 5 grips.  I have not had a chance to test them yet, but I see no reason they won't work. 

I made a manifold to distribute the compressed air to the machine.  It takes 90 PSI from the compressor and connects to the 4 pneumatic systems the machine has (or will have) which are the mister, the power draw bar, an air gun, and ATC (when that is done...).  Each line will have regulators and solenoids down stream to control the air.

I made the new mounting plate for the Nema 34 motor for the Z axis.  Fusion has been being a little bit weird since the last update (as is always the case with Fusion) and has been giving me inconsistent heights with 3D adaptives.  It doesn't make a lot of sense to me, since it will take a cut lighter than its maximum step down and leave extra material that it doesn't come back to cut.  This is with stock to leave set to 0 and "machine shallow areas" checked.  Anywho, the 2 contour for the motor face was at the right height, but the adaptive was about .02" too shallow.  It should still work, but its not a good look and isn't ideal.  I don't think that dimension is critical though, so I won't worry about it.  I just need to either make a new coupler, or open up the current one from 1/4" to 1/2".  I am not sure if it will fit, so a new one might be needed.  Then I can wire it up, give it the full 7 amps the drive can handle, and the head should be zipping along.

The enclosure has had some milage put on it, and even with the back ATC section still open, and only 1 door, it catches most of the chips.  I filled a 20 gallon storage container with chips contained in the enclosure, and in that time, the chips that escaped were maybe 3 inches deep in a 5 gallon bucked.  If I can just figure out the door mounting, and then mount the rear panel, it should contain nearly all the mess.

I know I have mentioned a new spindle motor a few times, but I left out the details until everything was squared away.  Another member here offered me a screaming deal on a servo motor and I just couldn't pass it up.  I don't know if that person is ok with me crediting him for it, so for now I won't say who it was.  The details were worked out and the new motor and drive are scheduled to be delivered tomorrow.  The motor is a 2 HP 6000 RPM AC synchronous servo with a matching drive.  The motor checked off all my boxes and then some (I wanted at least 1.5 HP, 5000 RPM, under 20 lbs, and fits on my machine). I plan to step up the spindle speed again, likely to 7500 or so.  I plan to use the current pulley arrangement to see how the spindle responds to higher RPMs.  With the current arrangement and faster motor, the spindle will get up to 13,200 RPM.  My bearings are rated for 13,000 and 17,000 RPMs, but I don't think the spindle is nearly well made enough to handle that without excessive vibration.  I would like to get it to 10,000, and maybe some balancing can make that possible.  As a side note, its insane the difference in documentation between the cheaper hobby stuff and the industrial stuff.  The hobby stuff comes with one 4"x4" sheet if you are lucky telling you basic dimensions and wiring.  Or if you are unlucky, you can't get any information at all about the motor has a 100 page manual detailing every aspect of the motor including wiring, duty cycles, torque curves, etc.  I have never used real equipment like this before so this was surprising to me.  I already have the mounting plate designed and once I verify the motors dimensions, it I just need to make the one plate, wire everything, and figure out how to program and control it.

Since the new spindle motor is a servo, it can be run in both velocity and positioning mode.  This opens up a number of new possibilities such as:
1. Rigid tapping
2. Indexing during tool changes
3. Holding position for using lathe tools with ATC
4. Indexing and holding for broaching corners

It would be pretty cool to be able to get the machine to hold a lathe tool in the spindle, cut a part using a lathe attachment, then use the ATC to switch to a drill or end mill and cut without me needing to do anything.  I may need to add a brake to the spindle to keep it held strong if I want to make this work.  But I couldn't be more excited for this thing and the things it may allow me to do.  At the very least, 2 HP and 6000 RPM should let me remove a lot of material very quickly.

I also tore the Y axis way cover.  When the table is close to the column, the way cover bunches up and gets caught between the vise and the Z axis way covers.  I guess the rubbing wore a hole, and at some point that hole got snagged and now there is a big jagged gash in the cover.  I would like to replace it either with accordion ways like the Z axis uses, or maybe some sheet metal or machined aluminum V covers. 

Have some pictures!

Here are the jaws and grips.  I don't have the correct screws yet, but they just need 10x32 countersink (what are the ones with an angled head called?) screws. 





Pneumatic manifold/distributer/splitter/air thingy, whatever you want to call it.





Z axis motor mount.  I didn't want to remake the entire Z axis motor/bearing block assembly, so the mounting plate for the larger motor also serves as an adaptor.  The holes inside the circle will attach the plate to the current nema 23 mount, then the larger outside holes will attach the motor.





Here is a drawing of the new motor mounted on the head.  With the air cylinder, spindle motor, and nema 34 Z axis motor, everything is a bit of a tight fit.


----------



## shooter123456

I made a little more progress after being out of town for a week.  I made the mount for the servo motor and I am getting going with programming it.  The drive needs to be tuned and it all needs to be wired in to the controller so the computer can run everything.  

I can confirm that the talon grips I made work.  I used them to make the motor mounting plate and the part didn't budge while cutting.  You might notice that the outside of the plate is a little bit rough... When the tool was profiling it, I forgot to set "stock to leave" to .015" so the finishing tool would have some material left to remove.  Oh well, it doesn't look terrible and it works, so I will use it as is. 





Finished product fresh outta the vise.





And in her first public appearance, the new Lenze servo spindle motor all mounted up and dwarfing the the Nema 23 Z axis motor.





I have been instructed by the landlords (Aka Mom and Dad) to hold off on breaking into the breaker box to steal a 220v line to run the motor at full speed, so for the moment, I am stuck using 120v power.  It works fine, but the speed is cut in half (Max speed of 7000 down to 3300) and torque suffers a little.  At the very least, it is still going to be more powerful than the stock spindle motor, and the max spindle speed is bumped up from 5500 RPM to about 7250.  Once I get the thing programmed and tuned, I will make some test cuts and see how it does.


----------



## shooter123456

I am still working on the Servo drive.  It has an old version of the firmware that does not have autotuning.  To get the new version of the firmware, you need a new version of the firmware already installed.  I might be stuck trying to tune it manually I am thinking.  I have sent 3 different emails to Lenze an all 3 were ignored (first sent 3 weeks ago) so I might be SOL in that department.  I also tried calling them, and their system puts me on hold for about 10 minutes, then sends me to voicemail.  No response there either.

Getting a little tired of working on the motor, I decided that I need to make something that isn't machine related on the mill.  Its been too long since I made something that wasn't an upgrade or a part for the machine.  With all this talk of "Ghost guns" in the news recently, I was inspired to make an AR-15 lower.  It would give me a chance to use all the upgraded parts I have added to the machine and hopefully let it run on its own for a while.

The first side needed 9 tools to complete.  They were

1. 3 flute .375" carbide end mill
2. 90 degree spot drill
3. 3 flute .250" carbide end mill
4. 3 flute .125" carbide end mill
5. 2 flute .625" insert end mill
6. .250" twist drill
7. .201" twist drill
8. .156" twist drill
9. 4 flute .375" ball nose end mill

This is the first time I used the mist coolant with actual coolant in the tank (in this case WD-40).  It worked well for the most part.  The only problem I had was that the flow of coolant would stop occasionally and I needed to open the needle valve on the side of the head to get it flowing hard, then turn it back down to where it was.  I am not sure why it is stopping like that, but I will figure it out eventually.  It was also very smokey.  The garage filled up with smoke from the WD-40 burning off pretty fast.  The door needed to be opened and fans run to keep it down to a more manageable level.

I used the mitee bite jaws on the vise and they did their job.  I had to switch one of the jaws to the outside of the moving jaw.  I couldn't tighten it too hard or the aluminum jaw would start to bend back.  That didn't seem to be a problem since tightening lightly held it in place very securely. 

For the first side, the mill ran for about 2 hours.  There were only 2 problems that needed to be corrected.  First, the .625" insert end mill started rubbing once it got down past 1" deep.  I had to take it out, machine away the shoulder that was there on the lathe, then put it back in.  It was nice to be able to pause the program, pop the tool out, fix it, and pop it back in and resume without any fuss.  The second problem was that I roughed to profile first, then roughed the features in with the .375" 3 flute end mill. With less than .1" left on the bottom of the part and being held in the vise, and the tool extended out of the holder to reach the 1.5" depth around the part, there was a lot of chatter.  I probably needed to back off the DOC and increase WOC instead.  

Here are all the tools used.





Here is how it started.  I just faced it flat before starting.





Here is the profile after the profile was roughed.





Here is the modification that was needed on the insert end mill.
Before: 





After:





Righter after it finished roughing the features in the top.  It is a good thing I paused it here to take a picture because while it was paused, we had some power flickers (a lot of storms in NC recently) and though we didn't lose power completely, the control computer rebooted.  If I hadn't paused it, it would have crashed in the middle of the finishing pass, dropped the head, destroyed the part, and probably damaged the vise.  





Here it is all done with the first side.  Next it needs to be flipped and the second half will be machined.





Here is a close up of the first 3D rounded contour I have ever done.  This was with the 3/8" ball end mill and I think it turned out very well.


----------



## phazertwo

Nice work!

Here is the coolant I'm using.  https://www.amazon.com/gp/product/B00R9M0110/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

1 gallon should last you quite a while once you get the mister dialed in.  The difference between WD40 and coolant is impressive, and I would imagine much better for you lungs!  Though coolant is not good to breathe either, so I wear my respirator when running mist.

PZ


----------



## shooter123456

phazertwo said:


> Nice work!
> 
> Here is the coolant I'm using.  https://www.amazon.com/gp/product/B00R9M0110/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
> 
> 1 gallon should last you quite a while once you get the mister dialed in.  The difference between WD40 and coolant is impressive, and I would imagine much better for you lungs!  Though coolant is not good to breathe either, so I wear my respirator when running mist.
> 
> PZ


I was hoping to avoid the respirator by getting it to run without fog... Does the coolant smoke at all when you are cutting?  I need it mostly to keep the chips from sticking to the tool, actually cooling isn't as much of a concern.  Does it lubricate the cutter as well as WD-40?

Also, do you dilute it at all before using it? Any discoloration on the part after using it?  I can't remember which one it was, but one of the coolants turned aluminum parts brown.

I want to get some real coolant though.  The WD40 is just what I have used with a spray bottle for the longest time and I had a gallon jug of it.


----------



## macardoso

NICE WORK!

Which indexable endmill do you use?  How does it perform in aluminum?  I'd like to use one, but I haven't found something that works well in aluminum and I can't justify the cost of a Tormach shearhog.


----------



## shooter123456

macardoso said:


> NICE WORK!
> 
> Which indexable endmill do you use?  How does it perform in aluminum?  I'd like to use one, but I haven't found something that works well in aluminum and I can't justify the cost of a Tormach shearhog.



I have a set of Zenit end mills that use AP?T (I think G but not sure).  There is a .75" 3 flute, a .625" 2 flute, a .5" single flute, and a .375" single flute.  I snagged the set of 4 of them, plus around 20 inserts for $50 shipped on ebay.  They work well for what I do, but I am not sure how they would compare to a shear hog.  I want one of those too, but also can't justify spending $240 on a single tool.  With the new motor, they are ripping through aluminum pretty hard.  The biggest cut I took after getting it set up tonight was 4.35 in^3/min, so at the very least they do as well as the shear hog if you can spin them.

NYCCNC recommends .2" wide, .2" deep, 40 IPM for using the shear hog with the Tormach 440.  That is 1.6 in^3/min.  The 440 also weighs at least double what the PM25 weighs, so I have trouble imagining the PM25 would be able to do much more than the 440 with the shear hog.


----------



## shooter123456

The spindle servo is up and running!! I can't believe how crazy this motor is compared to the stock motor.  Right now I am running it with 120v instead of 240v, so it is not achieving its full 2 HP rating and its speed is cut in half.  With the motor running at 3000 RPM, the spindle is moving at 6600 RPM.  I did a few test cuts with my insert end mills and it was moving!  

My standard roughing cut with the original motor was .3" wide, .05" deep, 35 IPM.  That gave me .525"/min MRR and the spindle motor would get bogged down a little bit at the start of the cut.  When I did the same cut with the AC servo, it didn't even notice it was cutting something.  I had a motor RPM readout on screen, and I think at the very beginning of the cut, it fell 2 RPM for just a second.  I started bumping it up until I got to the max feed which I had set at 96 IPM.  At .75" wide, .05" deep, and 96 IPM, the motor dropped about 200 RPM and stayed there.  It didn't sound like it was struggling but it was definitely working hard at that rate.  That was 3.6"/min MRR.  I had to reconfigure the controller to let me move the axes a little bit faster to see where the motor started to complain.  I got it up to 116 IPM (4.35"/min!!) before I backed off because the lights in the garage were starting to dim.  I am honestly not sure how that happened because the motor and drive were on their own dedicated 15 amp circuit, independent from the one the lights were on.  But I didn't want to risk it and destroy something just when we were getting going. 

I did a few test cuts that were deeper, but none of them sounded as good as .05" deep or could get close to the MRR before the motor started to struggle.  I did manage to stall it once, cutting .15" deep, .35" wide, at 70 IPM.  It only stopped for a second, but once I stopped feeding, it started right back up again.  I thought I would need to reset it if it faulted, but there was no recorded fault and it kept going when I slowed the feed down.  

I am running the spindle with an analog signal from LinuxCNC and it uses a relay to enable and disable the drive.  The breakout board has an onboard relay, but I couldn't reach the headers to wire it in, so I connected it to an 8 relay board I have in the box.  

I used the same pulley I had on the stock motor, I just needed to open up the bore a little bit to fit the larger shaft.  If I stick with the same pulley arrangement, the spindle will go 13,200 RPM once I hook the drive up to 240v mains.  I think it would shake itself apart at that speed though, so I will need to slow it down a bit and make a new spindle pulley.  

Here is the new motor next to the old motor next to the new Z axis stepper next to a 2.25 HP treadmill DC brush motor.  The new AC motor isn't much bigger than the stock motor, only slightly heavier, and at least twice the power.  German Horsepowers are a lot stronger than Chinese Horsepowers.





The huge chips from the .15" deep cut.  These were very loud running into the enclosure door.





I recorded a few of the cuts.  I really like the .05" deep one at 96 IPM.  The motor doesn't care, there is no chatter, the chips are cleared well, and I love the sound... I regenerated the tool path I used for roughing the AR15 lower, and the old one took 1 hour and 2 minutes.  The new one, using the new speeds and feeds finished in 15 minutes, 32 seconds.  Almost exactly 1/4 the amount of time!





I am going to mess with more feeds and speeds soon.  I think these inserts just like a shallow depth of cut.  There is a lot of space to explore between .05" and .1" deep though.  

Huge shout out to @phazertwo for providing the motor at such a great price and @macardoso for helping me configure and tune the drive!  This wouldn't have happened without them!


----------



## phazertwo

shooter123456 said:


> I was hoping to avoid the respirator by getting it to run without fog... Does the coolant smoke at all when you are cutting?  I need it mostly to keep the chips from sticking to the tool, actually cooling isn't as much of a concern.  Does it lubricate the cutter as well as WD-40?
> 
> Also, do you dilute it at all before using it? Any discoloration on the part after using it?  I can't remember which one it was, but one of the coolants turned aluminum parts brown.
> 
> I want to get some real coolant though.  The WD40 is just what I have used with a spray bottle for the longest time and I had a gallon jug of it.



I diluted it 10:1, and it seems to be working great.  It does lubricate well, and it didn't change the color of my parts.  Hopefully I can get the mister dialed to the point that I don't feel like I need to wear a mask, but for now it's not constant enough.

Nice work on the motor, I'm very excited by this!  I'm glad you're putting it to good use!  Those cuts are looking really good, if you gear it down a touch like you were talking about you should find a bit more torque which will help.  Of course getting it setup on 240v would be killer.  You've really got me thinking about what to do with the other one!

As always, great work!

PZ


----------



## shooter123456

phazertwo said:


> I diluted it 10:1, and it seems to be working great.  It does lubricate well, and it didn't change the color of my parts.  Hopefully I can get the mister dialed to the point that I don't feel like I need to wear a mask, but for now it's not constant enough.
> 
> Nice work on the motor, I'm very excited by this!  I'm glad you're putting it to good use!  Those cuts are looking really good, if you gear it down a touch like you were talking about you should find a bit more torque which will help.  Of course getting it setup on 240v would be killer.  You've really got me thinking about what to do with the other one!
> 
> As always, great work!
> 
> PZ


I will check it out, thank you for the tip!  Their price does not seem at all unreasonable.  When I was dialing in my mister, the pressure had to be crazy low to stop the fogging.  I think I have it set to 8 PSI on the air line and about 10 PSI on the coolant tank.  Even with the air line set to 15 PSI, it would fog like crazy.

I would love to see what the motor can do on a 940.  I think I am going to run into rigidity problems long before I find the limit for the motor.  I don't have a way to balance the spindle and tool holders at the moment, so I think I will limit the speed to about 8000 RPM.  Right now it is geared 1:2.2.  Their torque curve for the motor and drive at 120v stops at 2500 RPM (I was running at 3000), but if that graph is accurate, the motor was able to produce 3.39 Nm, which translates to 1.54 Nm at the spindle.  Once hooked up to the 240v line, I will be going to 1:1.3 gearing, which at the same 6600 RPM at the spindle will give me about 2.25 Nm at the spindle.  If I drop the motor down to 4000 with the spindle at 5200, it should give me 3.5 Nm at the spindle.  The torque curve claims that at 2000 RPM, the motor can put out about 8.75 Nm, which should be plenty of torque at lower speeds.  The motor also claims to have a top speed of 7000 with a slight reduction in torque, so that would give me 9100 RPM for using smaller cutters if I can balance the spindle a little better. 

My Dad will be home this weekend and he is going to help me run the 240v line to the drive.  I am going to make a separate electrical enclosure for the spindle drive to try to avoid noise and avoid building a new enclosure big enough to fit all of the electronics.  Let me know if you need any of the info I used to get it running.  Again, I can't thank you enough!  This is a massive upgrade and I couldn't walk away from the machine since I was having such a blast turning scrap aluminum into chips.


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## shooter123456

I didn't realize I hadn't posted anything for so long... Whoops!

Since my last post I have:
1. Connected the servo drive to a dedicated 220v line (I keep saying 240, but I think its actually 220).
2. Run an AC line to the shop, no more 100 degree 80% humidity afternoons.  Also I am not having any trouble with drives overheating.
3. Straightened the ballscrews, cleaned up the ballnut faces, and shimmed the nuts to increase preload.
4. Cut down the Y axis nut mount a little to slightly increase travel.  I got about .375".
5. Started machining parts for a lathe attachment using the stock motor and quill bearings.
6. Machined a stepper coupler to connect to the Nema 34 shaft and mounted the Nema 34 Z axis motor.
7. Machined the second side of the AR15 lower.
8. Made a threadmill tool and threadmilled for the first time on the mill.
9. Made all 10 tool fingers for the automatic tool changer.

Connecting the servo motor to the 220v line did several things for me.  First, it increased the output of the spindle motor to 2 HP from 1(ish) HP and the speed from 3000 to 6000 (Max speed actually 7000).  Second, it took the spindle load off of the 120v lines in the garage.  I was using 2 15 amp 120v lines to run everything in the shop.  This meant that I could not run 2 of the larger power consumers at once (Milling machine, lathe, bandsaw, or air compressor) since any 2 at once would cause both of them to strain, or if the mill tried a heavier cut while anything else was on, it would trip the breaker.  If I split the mill between the 2 120v lines (Spindle power on 1, control power on the other), when the air compressor kicked on, it would cause enough of a power flicker to cause the control computer to reboot.  No bueno when it is cutting.  Now, I have a free 120v line that can run the other machines while the mill is cutting on its own.  So I can leave the compressor on to recharge, I can prep stock on the bandsaw, or work on the lathe while the machine is doing its thing.

AC in the garage is possibly the greatest thing I have ever done.  In the past, I would soak through multiple shirts with sweat in one day and the machine would occasionally overheat the stepper drives.  Now, its still warm, but much more tolerable.  I have not yet insulated the door, but I can keep it around 80 to 85 degrees with the inside thermostat set to 75.

The X axis ballscrew was starting to concern me.  The tail end would wiggle at least .250, if not more, when the table was farther to the right.  It was also way too far out to support that end without binding issues.  To straighten them, I took a pair of V blocks and a dial indicator and put them on my X2 table.  I measured the point of max runout on the screw, then used the mill head to push on the highest point until it didn't spring all the way back.  That took a fair amount of force.  With the V blocks placed about 12 inches apart, the highest point was about .025" out and roughly 3/4 of the way down the screw on the drive end.  Once I got that down to .005 or so, I just kept moving it back and forth until I found what point was the most out of round and pushing and working the screw into somewhat straight.  Initially, I found 1 major bend, and 2 more minor bends (about .01" each).  After straightening, I was able to get everything in to about .003" at the worst points.  I didn't measure the machined end, but I wish I had.  Once reinstalled, the far end of the screw wiggles maybe .01" and there is no longer an audible oscillation while the table moves.

I re-cut the faces of the nuts using soft jaws on the lathe.  Most of the faces were rough machined and not ground, and looked pretty bad.  The front of the flanged nuts on both were pretty bad too.  I had to go off the assumption that the ball races would run true with the ground body of the nut.  This may not actually be the case, but I didn't know how to measure off the ball races, and its not like I could make them much worse.

Here is the set up for the nuts facing. The nuts were definitely hardened, but cut well with carbide.  In theory, the soft jaws ensure perfect (or at least very very good) concentricity.






Here you can see how far out the face of the nuts were.  I had to take off about .015" to get it squared up.





Oh yea thats much better.





I always forget just how many fasteners the machine has and how many little components there are.





The extra shims preloading the nuts let me get the backlash on X and Y from about .0035" to .0015".  I would like to get that even better, but I am happy with .0015.


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## shooter123456

I started working on a lathe attachment/4th axis for the machine as well.  I am using the stock 1 HP BLDC motor and the large bearings from the quill for it.  I have an idea for getting it to index automatically, but I don't think it will have full 4th axis capabilities.  But 3+1 would be possible. 

The 2500 rpm motor is going to be pulleyed down to 1000 RPM which should provide plenty of torque.  I don't ever run my lathe faster than 1000, so I figured that would be plenty.

As with most of my projects, I started with some scrap plates.  All of them had to be cut to size on the bandsaw before going on the mill.  Who would have thought a little $150 bandsaw would be used so much and make my life so much easier?










I had to open up the bearing pocket for the front plate by about .002" for a heavy sliding fit (is that a thing?)  I am very happy with that surface finish.





The rest of the parts were cut using a super glue fixture.  Machining them was pretty uneventful and the machine ran on its own for a while with no issues.  It probably ran for at least 6 hours that day.










Here is a look at almost all the parts and stock that will be used.  I have not decided if I want to put a tapered bore on the spindle.  I am trying to find a 2 piece jaw 4" 3 jaw chuck, but I have been unsuccessful so far.  





I used a fixture to machine the second half of the AR15 lower.  This was also uneventful (which is good) and it cut very well.  Everything lined up nicely and it didn't move at all in the fixture.  





I think there is a little bit of nod in the head somehow.  It is trammed well left to right, but it might be off a little front to back.  I am still happy with these finishes though.





This was one of the more interesting set ups I have done.  I clamped my 3" toolmakers vise in the 4" vise, then used a clamp to hold the lower upright against the 3" vise.  Here it is threadmilling the rear thread.





Its not the prettiest thread, but it works.  I will need to buy a decent threadmill.  They are a bit expensive though and I don't often need to threadmill.





I am thinking I will add another line for dedicated air coolant.  With the mist, there is not enough pressure to clear chips from deeper pockets and it starts to recut chips if I don't blast them out with the air gun.  I will just need some more locline and another solenoid valve.  

I bought some stock to make a sheet metal brake to bend some sheet metal.  I am going to try to make new way covers for both the Y and Z axis, as well as a cover for the head to keep chips out of the pulley and upper bearing.  I have not decided how exactly I will do these covers, but I will figure it out as I go.


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## shooter123456

I got the 4th axis close to ready today.  I machined the spindle shaft, finished the back side of all the 4th axis plates, drilled and tapped some holes, and did a quick test assembly.  It is short 2 pulleys and 2 lock nuts before it can run.  Then I need to find a 4"chuck with 2 piece jaws and/or come up with a vise to use with it.  

Here is the shaft after everything but the front end machining.





Here is the backside of the rear plate being machined.  It is cutting the face that will mount the motor.





Test assembly.





There's the repurposed spindle motor.


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## macardoso

Nice finish on the 4th axis spindle! What steel?


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## shooter123456

macardoso said:


> Nice finish on the 4th axis spindle! What steel?


Thank you!  It is 12L14.


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## macardoso

Very nice! Just a thought, but you could either machine the pilot diameter for a front mounting bolt-thru chuck, or you could put a 5C taper in it.


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## shooter123456

I always thought that given enough time, these machines will pay for themselves.  I had my houses backflow preventer inspected recently and it failed the inspection because one of the check valves was leaking.  They said the ears used to install and remove them had broken off so it was damaged beyond repair.  A new one runs anywhere for $250-$350.  So I said to myself "I have all these machines, there has to be a way to repair this item that is damaged beyond repair."  

First thing to do was remove the damaged check seat.  It actually wasn't too hard.  I just used the lathe to turn down a rod to the ID of the check seat, then superglued the rod to the rubber seat, and twisted it out.  






I got a new check seat (actually an entire service kit with 2 check seats and o-rings and such) for $21.  Turns out putting the new one in is kind of hard.  But wait, they sell a tool for it!  For $160... I said not today, parted off the part of the rod with the superglued seat on it, stuck it in the mill and cut 4 little grooves in it, then boom 5 minute later, the new seat was installed.  






In my eyes, the 2 machines just earned at least $230 (a penny saved is a penny earned right?) with about 20 minutes of work.  A shop rate of $690/hour isn't bad right?


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## shooter123456

In an attempt to finance some new machine parts, I thought to myself "Self, lets try to make a few kits for sale!  Maybe there is a market out there!"  So I have had the machine choochin hard for a few weeks now trying to get a few parts that looked great and make sure I have the programs all tuned in right.  It is basically the same design as the one I have had on the machine for 7ish months now, except I added some chamfers and radii to try to make it look a little nicer.  

I wonder if my idea regarding the kits is any good though.  I would welcome feedback here.  My thought is "I make the custom parts that need to be machined, then the user sources the hardware like ballscrews and bearings that are available through 100 different vendors."  Theoretically, if you were looking to convert a machine and could save $200-$300 over the other offerings by sourcing your own hardware, would that be an attractive option, or would you prefer to pay a bit more and get everything all at once from one person?

Here's a few pictures of the parts so far.  They all need a bit more work done and I need to make some flanges.  I love how the chamfers from the 3/8" spot drill look.  So much easier and cleaner than deburring by hand.  The pics are a little dark because I turned a few lights off.  Otherwise you can't see much on the part besides the reflected glare.


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## phazertwo

I think it's a killer idea.  Honestly, I would offer up different levels of kits...  Keep a hardware set on hand and have it ready to ship, just in case some one wants a more complete kit... Assuming you have the financial and storage means to carry some inventory.  You could also provide a hardware list, so they can just order it themselves.

The parts themselves look pretty dang good.  The only criticisms I have is (A) I would try to use a fly cutter, or face mill on the flat surfaces you get a super smooth finish.  (B) come up with a logo/name, and etch it into the big parts.  That's really just aesthetics though.

Last I would say find someone on the board here that would be willing to give it a try.  Hopefully someone that is willing to help you out with pictures of install so you can build some good instructions (if you want to take it that far).  Once that mill is up and running have him take a bunch of vids to send you so that you can post them, some with the thing just chewing the some Al.

I could see this being a nice little side business, and with your skills I bet you could build some cool fixturing to really save you time and make nice parts.  If it works, you could branch out to other machines... A kit for a PM-833T would be killer. (https://www.precisionmatthews.com/shop/pm-833t/)

As always, solid work!

PZ


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## shooter123456

I appreciate the feedback! 



phazertwo said:


> Honestly, I would offer up different levels of kits... Keep a hardware set on hand and have it ready to ship, just in case some one wants a more complete kit... Assuming you have the financial and storage means to carry some inventory.



There are a few reasons I wanted to offer only the machined hardware and not the ballscrews and bearings.  
1. I couldn't buy anything in enough quantity to get a wholesale discount, so I would be paying the same price anyone else would, except I would need to pay for shipping twice.
2. I would need to support the ballscrews and bearings and make sure they were decent quality for a decent price.  If a set is bad, then the purchaser has to ship them back to me, then I would need to ship them back.  Again, paying for extra shipping.
3. I wouldn't be offering anything different than everyone else selling kits.  Competing directly would be tougher than offering something different.
4. People can re-use ballscrews they already have, purchase used ones, or take advantage of any sales or discounts.  
5. I don't really have the extra money and space to buy a few sets and store them.  



phazertwo said:


> The only criticisms I have is (A) I would try to use a fly cutter, or face mill on the flat surfaces you get a super smooth finish. (B) come up with a logo/name, and etch it into the big parts.



More good feedback, thank you.  I have a face mill that creates fantastic finishes, but they are not perfectly flat.  I figured the part being flatter would be better compared to looking nicer.  Though for most of the parts, it doesn't matter how flat they are, so it looking better could be the better way to go.  I have been thinking about a logo, but I am not the creative type.  That is good advice though, I will try to come up with something. 



phazertwo said:


> Last I would say find someone on the board here that would be willing to give it a try. Hopefully someone that is willing to help you out with pictures of install so you can build some good instructions (if you want to take it that far). Once that mill is up and running have him take a bunch of vids to send you so that you can post them, some with the thing just chewing the some Al.



Is there any reason you would find someone else to do it, instead of just putting it on my machine and taking the pictures/videos with that?

Again thank you for the feedback!


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## phazertwo

Those are 5 good reasons not to get into the hardware business lol.  You have obviously thought this out!  In this case I would say just provide a drawing of what the ball screw needs to be... MAYBE go so far as to provide some part numbers for ball screws you know will work.

As for flatness vs finish... As a general rule I tend to pick function over form each and every time, however if you can make it look significantly nicer and not detract from the function, or add significant cost... make stuff shinny.  I would challenge you to evaluate your parts, and make drawings with realistic tolerances.  Like you said, some of those surfaces don't need a flatness on them at all... better to make them look nice.  Remember people on the interwebs make decisions based on pics they see...  It's marketing really.

As for a logo... Start with just a name, and etch it, or an abbreviation into a few parts.  More marketing really, you just need to make sure that if someone sees some pics of it on the interwebs they know how to find you.

Last, I was thinking that you would keep yours up and running, but if you're going to tear it down, DEFINITELY write the instructions as you are assembling (IMO no instructions is not an option).  MUCH easier to do it all yourself.  HOWEVER... I would still find a guinea pig and have them install and post all about it.  Again, marketing.

PZ


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## bakrch

Great thread!

I had similar issues with my ball screws, but they work ... for now.


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## Karter44

With all the photos of a dis-assembled mill in this post, how difficult is it to remove the head and table and then re-assemble?  I have a basement workshop but there is no room on the basement stairs to take down a complete mill.  I have restored a '40s Logan lathe but I have never worked with milling machines before.  I do have a knock down engine hoist that can be used.  Thanks for the help.


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## shooter123456

Its not hard at all. The head is very easy to remove, but I would remove the spindle motor first, otherwise it is very top heavy and has a tendancy to swing around hard when you loosen it up.

To remove the head, there are just three nuts that need to be removed and it pops right off. It weighs around 60 lbs, so be ready for it. There is also a little spike at the bottom to point to the head angle, and its a bit hazardous.

The table is about 55 lbs if I remember right and also comes off pretty easy. You just need to run the table to the end of its travels, remove the end blocks and loosen the gib up and it slides right off. Be careful when it is at the end of the travel because it may tip a little, especially if the head is already off.

Reassembly isnt too bad. The tough parts are getting the X axis gib back in place. I needs to be wiggles and nudged to get it to sit right. The head can be a pain in the butt to get the screws lined back up, but that is the hardest part. Then it just needs to be trammed back in.


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## shooter123456

Trying to make a lot of parts gave me a chance to push the machine harder and try to get even more out of it.  I am making motor risers and at first it was taking about 10 minutes for the first operation for each part.  I sped things up and got it down to about 5.  I posted a video of it moving pretty quick if anyone wants to see.


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## phazertwo




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## phazertwo

What is your max RPM right now?  Looks like she was cooking!

Also, consider ditching the drill op... Looks like your pretty much machining it out with the end mill anyway.

PZ


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## shooter123456

phazertwo said:


> What is your max RPM right now?  Looks like she was cooking!
> 
> Also, consider ditching the drill op... Looks like your pretty much machining it out with the end mill anyway.
> 
> PZ


Holding steady at 7500.  Can't really push it higher without a good deal of spindle work.

I didn't really want the drilling operation in there, but without it, there was trouble getting into the corners.  The 1/4" end mill doing and adaptive cut would leave a lot of material.  Then doing a 2d contour to finish it, there would be a lot of chatter when it got to the corner.  When I used a 1/8 end mill to do the adaptive, it got into the corners just fine, but took 4x as long to do it.  The drill time for that operation is 32 seconds (and I have been running 2 parts at once and the other part needs holes drilled, so the drill will be in the spindle anyway) and so far is the best way I have been able to figure out how to do it. I think if I spent some time figuring out ideal feeds and speeds for drilling, I can speed it way up.


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## shooter123456

I think it is time for the direction of this machine to change.  I have been in college for the last 4 years and for the most part, I have had an abundance of time and a very limited budget.  Well I am graduating in 2 weeks and I have started a new job.  As the stars have aligned, those two have reversed.  I now have an abundance (well compared to what I am used to... which was no money) of money to spend and limited time.  So now, I need the machine to work faster and more reliably, even if that means some things will be more expensive.  

So its time to re do the machine I think.  I would like to tailor it more towards production and reliability so I can design a part and output some toolpaths, then stick a piece of stock in the vise and press start, then come back however many hours later and have a finished part waiting for me.  Ideally, I could get the machine up and running in 10 minutes or less, and not have to worry about a thing, even if that means I don't come back to the machine until the next day (or next several days).  So what will I need to accomplish this?

1.  Servos.  I just don't trust steppers to run that reliably for long amounts of time without me checking in on them.  I also would like the increased speed from servo motors and the fact that servos are much smoother is a big plus.  Right now I am looking at DMM 640-DST-A6HS1 motors and DYN4-L01A2-00 drives for X and Y, then 86M-DHT-A6MK1 and DYN4-H01A2-00 for the Z.  All in, those would run $1415 and would give me (theoretically) 1000 IPM rapids (more likely 400 IPM rapids) and cutting feeds in the 200 IPM range.  Alternatively, I am looking at clearpath servos, which I haven't been able to decide on a model, but it looks like it will be roughly the same price, but I would get to try them out for 3 months to see if I like them first.  I could also put servos on X and Y just for the running smoothness and rapids, then if the machine makes any money, add a servo the Z.  

2. Flood coolant and new enclosure.  My enclosure was meant to be quick and easy to contain some of the mess.  It did that for sure, but I want something that will be water tight (ish) and allow for flood coolant.  I sort of like mist coolant, but it doesn't do a great job with pockets and holes, and it is a bit unreliable for me.  It is also tough to get it to work with different tool lengths without adjustment.  I am working on a design for an enclosure made of steel instead of wood (I got a welder a few months ago and messed with the exhaust on my car to learn to use it, now the car is louder and I sort of know how to use a welder) and sheet metal instead of MDF.  It will also be stronger and more rigid so it doesn't shake like crazy when the machine accelerates hard with the servos.

3.  Auto tool changer.  There is only so much the machine can do without me changing tools constantly.  I made an auto tool changer and it had a lot of problems.  So much so that I decided not to show it at all and keep it to myself.  I have tweaked the design and changed a ton on it, and once the stock and parts come in, I will try tool changer take 2.  It will need sensors out the hoorah to make sure that if it fails, the machine doesn't continue running and break everything.  I have nightmares thinking about a partial index causing the machine drop down and break the tool changer, then have it continue running and break something each time it smashes into the tool changer.  Don't want that nonsense. 

4.  Ground ballscrews.  My ballscrews are rough and I don't love them.  If I can find ground ballscrews for a semi reasonable price, I will buy them in a heartbeat.  This doesn't need much explanation.

5. Remote control.  My house is wired with security cameras, and I can check on them with an app on my phone.  I also learned how to use remote desktop at my old job.  I feel like these can be combined so I can keep an eye on the machine when I am away, and maybe even have it do stuff remotely.  This is just a nugget of an idea, but who knows...

6. Probe.  I would like to make a probe so I can fixture something and tell the machine to do its thing.  I think the most time consuming part at the moment besides work holding is using a wiggler to touch off the workpiece.  A probe would speed this way up.  If I can't make a probe that is reasonably accurate, I will look into buying one.  

7.  A new control computer.  The one I have is an old work surplus machine that isn't all that great.  It works but it has its glitches (for example, 1 in 10 times when I remove the USB drive, the computer restarts) and it isn't all that reliable.  I want one that will work all the time and minimize the time I spend redoing set up work because it conked out for some reason.

8.  Spindle work.  The spindle on the machine is like a 4 out of 10.  It needs to be balanced and have a few other improvements made so it can run fast without vibrating.  I want a better surface finish that it just can't handle.

9.  Head spacer.  The machines spindle isn't centered over the Y axis travel, so in order to use the whole thing, parts need to hang off the front of the table.  This often makes them run into the column.  You also lose a lot of travel when you use a vise.  I would like to fix that.

I would love some feedback on all this.  If you have ideas for things I could get to improve it, I am all ears.  My idea is to make it out perform a Tormach 440 (which I consider the closest competition, though my machine has more travels) by far, for less than half the price of an equivalent machine ($14,500 for the machine with tool changer and enclosure). 

Like everything for this machine, I hope it will only take a few months, but I am sure I will be halfway done by next Christmas...


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## phazertwo

I'm interested to see what you come up with... Servos and a encloser that can handle flood coolant are the things I dream about at night.  If you and Jake both figure out servos, it should be a walk in the park for me!

We should compare spindles.  Do you have a model of yours that I could compare to mine?  I've been doing a lot of dreaming of a spindle that has stacked AC bearings and can turn 10k rpm... but this means a whole new spindle, and probably quill.  I've been thinking about how to do this in a smaller lathe and hold everything as concentric as we would need it... if our spindles are the same, I'd be willing to split some of the development effort with you.

PZ


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## shooter123456

phazertwo said:


> I'm interested to see what you come up with... Servos and a encloser that can handle flood coolant are the things I dream about at night.  If you and Jake both figure out servos, it should be a walk in the park for me!
> 
> We should compare spindles.  Do you have a model of yours that I could compare to mine?  I've been doing a lot of dreaming of a spindle that has stacked AC bearings and can turn 10k rpm... but this means a whole new spindle, and probably quill.  I've been thinking about how to do this in a smaller lathe and hold everything as concentric as we would need it... if our spindles are the same, I'd be willing to split some of the development effort with you.
> 
> PZ


The DMM and clearpath servos are supposed to be very easy to set up and use. I anticipate clearpath being much easier then steppers from what I have seen. The reason I have never used them is just because of cost. 

I have a model that I can send to you tonight. I don't think the two are very similar though, yours is a whole lot bigger. Mine is really quite tiny and unimpressive. Ive considered making an entire new spindle, but I don't know that it would be worth it for this particular machine. I would need to replace the head as well, and I would probably want to change it to a BT30 instead of R8. I think I can get this spindle to run acceptably at 10,000. I will need to remachine the threads at the top and replace the r8 collet it is currently using (threads arent super straight on those either), then see if I can use a phones vibration sensor to get it balanced better. If that all works, it should run much smoother and vibrate less.


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## shooter123456

I have been visiting my parents for Christmas, so I have been away from the shop for a few weeks.  That means plenty of time to model and design stuff.  I made a number of changes to the design of the tool changer because there were a few things that weren't quite working for me.  

First was the tool fingers.  They were a little bit over complicated, had very small parts that needed to be made, couldn't get enough spring tension in the space that I had left, and they required a very accurate tool holder geometry.  The diameter of the groove had to be very specific and even when they were close, it would either be super tight, or somewhat loose.  I didn't like that, so I changed the design to a 2 piece finger design that rotates on a shaft and are forced apart at one end by a spring so they grab the tool holder on the other end.  I saw a very similar design on Haas tool changers so I figure it has to be a decent design.  I started making some of those parts before I left and I think it should work just fine.  

Here are is the updated version of the tool changer, from the bottom.  You can also see some cut outs in the tool platter to try to reduce the weight.






I also decided to just buy an air cylinder instead of making one.  I was having a heck of a time boring out a bar to use (accurately) and an already finished one made of stainless steel was only $24 brand new.  Screw it, I bought it instead. It is a 2 stage cylinder with a 4" stroke.  That will be plenty for the tool changer.  It has a little over a 1" bore which will let me push it with 150lbs of force if I need to.  I don't anticipate needing to use more than 30ish lbs.

I ran into some trouble with the motor that is used to rotate the tool changer.  I was concerned that it wouldn't have enough torque to rotate the tools.  The tools rotate on an axis with a diameter of 4.5".  Considering only the weight of the tools, estimating 1 lb per tool (conservatively, more likely each tool will weigh less), that gives me 10 lbs (160 oz) rotating at 4.5".  To move them, I would need 720 oz/in of torque (if my math is right, it is very possible that I am miscalculating completely).  I am using a 400 oz in stepper, so it might struggle.  To mitigate this, I made a 2:1 gear box that will double the torque and hopefully let me rotate the tool changer without trouble.  






I am planning to make some changes to the pneumatic draw bar as well.  Right now I am using a 3 stage air cylinder with 3" pistons.  The springs I am using have a working load of 900 lbs and a flat load of 1200 lbs.  I am running them in pairs giving me 1800 lbs of working force and 2400 lbs to release.  At 115 PSI, that gives me enough force to release the tool.  The plan now is to add another spring to give me 2700 lbs of holding force and 3600 lbs to release.  This will let me push the tool a bit harder without worrying about it pulling out.  To get the 3600 lbs of release force, I will add another stage to the air cylinder and push the pressure up to 130 psi.  That will give me 3675 lbs of force to release the tool.  

Last, I got a deal on some vises on ebay.  I got 2 4" machine vises for $85 each that seem to be good enough for what I want to use them for.  I now have 4 vises, and they should all fit on the table of the machine, letting me run 4 parts at the same time, or maybe run OP1 on 2 vises, then OP2 on the second 2 vises.  I think this and the tool changer should let me really ramp up the production capabilities of the machine. 

Here is a look at the 2 vises I received.  They have the flat sides which should let me get them in much closer to each other and save some space.  For what I paid, I am very pleased.  






Here is how it should look when I get all 4 mounted with the tool changer.


----------



## macardoso

Awesome job on the ATC! I can't wait to see the real deal.  I have mine 90% built and laying in a corner. You're making me want to go finish it up.


----------



## macardoso

Also, from having designed and built an ATC from the TTS system, be aware that the slot on the tool holder is very finicky and intolerant of misalignment. It has caused me a lot of problems in the past. I'm happy to share any design files for my ATC which might help you.


----------



## Firstgear

welcome to the land of tax payers!

I saw that your posting on the coolant lines that occasionally stopped flowing, that you had to turn the needle valve open and when it started flowing again you turned it back down.  If you want this to run automatically that cant happen.

Couple of thoughts...
1. on the inlet side before the needle valve put an inline filter.  You can get these at Tractor Supply or Rural King (or Ebay) for about $5-$8.  Look for the filters that are used for home spraying systems (I have one I pull behind my garden tractor when I want to spray weed killer in the yard).  I would start with the smallest screen mesh they have since the viscosity of what you are dealing with is just above water.  This will eliminate any very small particles that get into the coolant as it wont take much across that needle valve to plug it enough that requires manual intervention.  Another filter that would work would be a paint filter, like is used for a manual spray gun.  This might be a better way to go since they may make them with smaller mesh size.  At any rate you can try one of them.
2.  After putting the filter in place, if you still have problems, get a more accurate regulator.  if you are using 5psi, make sure that you are using a regulator that is 0-15psi....you want that regulator to not be sitting too close to off...that will raise hell with you too.
3.  Not sure what you are using for a needle valve but the same issue here.  If you cant control the pressure feeding it the needle valve will have to take the pressure drop meaning it will be hardly open, again, it wont take much to choke off the flow requiring you to open it and then after what ever it was cleared, then setting it back again....you might need a better needle valve....

Having built systems before in my work life, these were the kinds of things that often tripped me up.  These systems were going into automated systems where there were no human eyes so they had to work.  That is what you want.

Let me know your thoughts....


----------



## phazertwo

That really looks great.

As far as torque is concerned for rotating the ATC when there is no external force being applied to the assembly (is spins free save friction): Torque=Angular Acceleration * Moment of Inertia (τ=αI). Moment of Inertia is a term takes into account size, shape, mass ect. of the object that is rotating. τ=αI is actually just the rotational equivalent of F=ma for linear motion.  Except F is replaced with τ, m is replaced with I, and a is replaced with α.

I could go into more detail, if you like, but long story short, you won't need the gear box to spin the ATC.  I think there is a way to get Fusion to tell you your moment of inertia, if not I think I can get it in SolidWorks.  Or we can roughly calculate it and get close enough.  *OR* I'll beat my inner nerd back to where he belongs.

As always, inspiring work.  Your video "Pushing PM-25 CNC Faster" actually got me off my ass and working on my machine!

PZ


----------



## shooter123456

Firstgear said:


> welcome to the land of tax payers!
> 
> I saw that your posting on the coolant lines that occasionally stopped flowing, that you had to turn the needle valve open and when it started flowing again you turned it back down.  If you want this to run automatically that cant happen.
> 
> Couple of thoughts...
> 1. on the inlet side before the needle valve put an inline filter.  You can get these at Tractor Supply or Rural King (or Ebay) for about $5-$8.  Look for the filters that are used for home spraying systems (I have one I pull behind my garden tractor when I want to spray weed killer in the yard).  I would start with the smallest screen mesh they have since the viscosity of what you are dealing with is just above water.  This will eliminate any very small particles that get into the coolant as it wont take much across that needle valve to plug it enough that requires manual intervention.  Another filter that would work would be a paint filter, like is used for a manual spray gun.  This might be a better way to go since they may make them with smaller mesh size.  At any rate you can try one of them.
> 2.  After putting the filter in place, if you still have problems, get a more accurate regulator.  if you are using 5psi, make sure that you are using a regulator that is 0-15psi....you want that regulator to not be sitting too close to off...that will raise hell with you too.
> 3.  Not sure what you are using for a needle valve but the same issue here.  If you cant control the pressure feeding it the needle valve will have to take the pressure drop meaning it will be hardly open, again, it wont take much to choke off the flow requiring you to open it and then after what ever it was cleared, then setting it back again....you might need a better needle valve....
> 
> Having built systems before in my work life, these were the kinds of things that often tripped me up.  These systems were going into automated systems where there were no human eyes so they had to work.  That is what you want.
> 
> Let me know your thoughts....


I hope uncle sam enjoys  living large on my hard work 

I will keep your thoughts in mind.  I think a filter is probably a good idea, but the issue has largely gone away on its own.  I switching to koolmist from WD-40 helped a bunch, and I think the WD-40 may have been clogging the lines a little bit for a while after.  It is definetely a cheap thrown together system.  The needle valve is one I found in the garage, probably form an old refrigerator and the mist system parts are almost completely from an RO water filter.  The regulator is an inexpensive one and I am not sure what the rating on it is.  If I redo the mister, I am going to follow your advice and add a filter and a better regulator.


----------



## Firstgear

If you stated earlier, I am sorry if I missed it.  What are you building this machine to make?  Are you trying to get in the machine shop business?  Make your own products you plan to sell?


----------



## shooter123456

Firstgear said:


> If you stated earlier, I am sorry if I missed it.  What are you building this machine to make?  Are you trying to get in the machine shop business?  Make your own products you plan to sell?



The machine is for personal projects, I am just trying to make a few things to sell to fund more parts for the machine.  Not planning to get into the machine shop business.


----------



## adhue587

Hi,

You've done an awesome job at getting this designed.  Any chance you would share your 3D models?
I have a PM-25MV and really want to get it CNC ready.  The Power Drawbar and ATC are awesome too.


----------



## shooter123456

The new servo motors got in.  I got 2 CPM-SDSK-2321S-RLN  motors for the X and Y axis and CPM-SDSK-3421P-RLN for the Z.  Needless to say, they are quick!  I am using the same 48V power supplies I used for the steppers, so the motors are limited slightly from their full ratings at 75V.  I am probably going to buy a Clearpath power supply sometime soon to get them up a little bit and to run it off of 240v AC input since I have a 60 amp line for it.  

I am now getting 400 IPM rapids on X and Y and 250 on Z.  The set up was very easy and they are very smooth.  They are also much quieter than steppers.  You usually hear the ballscrew turning now instead of the stepper whine.  They are plenty strong for this machine and I am very please.

Here is a video showing a short before and after.


----------



## phazertwo

Very nice!  I like the speed, it really is impressive.  I'm very excited to see you tear up some Al.

Care to share why you went with Clear Path?

PZ


----------



## shooter123456

phazertwo said:


> Very nice!  I like the speed, it really is impressive.  I'm very excited to see you tear up some Al.
> 
> Care to share why you went with Clear Path?
> 
> PZ


Thank you!

I went with clearpath for a number of reasons.  I was really only considering them and DMM because I wasn't aware of any others that weren't either no name Chinese imports or 3x+ the price.

Clearpath won because:

The sales guy was very clear and straight forward, providing me with a ton of information and making it easy to choose which ones were best for me.
The DMM sales guy just quoted me for the most expensive Nema 23 and Nema 34 items they had and didn't seem to think it was overkill even though they were 3x the power of what I have now.  Ended up being more than $600 more expensive for very little gain.
Clearpath lets you try their motors for 3 months and return them no questions asked if you are not impressed.
Clearpath autotuning is simple and easy, the DMM ones were not nearly as straight forward.
I can use the Clearpath motors on my machine without buying new power supplies.  Saves me a few bucks for now.
Drives are attached to the motors saving me space in the electronics box.
The information available on the Clearpath motors was much more clear and thorough than DMM.  They also seemed to have their stuff together a lot more (ie their site looks professional and is easy to navigate vs DMM which looks kinda like an ebay store selling rebranded motors.)

It wasn't a super tough decision really and I am happy with the performance.


----------



## phazertwo

Good to hear they have some good customer service!  A 3 month no questions asked return is a pretty sweet deal as well.

PZ


----------



## Larry42

shooter123456 said:


> Motors are mounted and axes are moving.  Looks like my careful measuring at the beginning paid off because every part went on without an issue and the machine moves smoothly.
> 
> Here is the Y axis motor mount.  The ballscrew I have on the Y is about an inch too short so I am down to 6" of travel.  When the funds allow, that will be replaced with a longer double nut screw.
> View attachment 257206
> 
> 
> Here is the X axis mount.  The picture isn't very good because the lighting is bad.  I need to get some more light over in that corner of the garage.  The X axis loses 5" travel with the current ballscrew.  This one will also be replaced with a longer double nut screw when the funds allow for it.
> View attachment 257207
> 
> 
> Here is the Z axis.  This unfortunately isn't going to last as long as I hoped it would.  The 400 oz in motor didn't have the torque to reliably move the head.  The motor would not lift the head under 60 IPM or over 120.  At 50 IPM, it would try to move it, maybe make a quarter of an inch, then the head would fall as the motor strained.  At 75 IPM, it would move the head well, but would stall roughly 10% of the time when it was lifted.  I am looking at Nema 34 motors and drives now to replace it.  I think I will make a simple adapter plate to allow the Nema 34 to mount to the Nema 23 mount.  I am thinking somewhere in the 900-1200 oz in range.  Since there will be a pneumatic cylinder and potentially a larger motor on the head, I want to have a little extra power so I can move it quickly without needing any counter weight or spring helping to push the head up.
> View attachment 257208
> 
> 
> I was hoping the 400 oz in motor would last a little while on the Z axis, but my hand has been forced.  I was getting set up to do some test cuts when something exploded inside the power box.  The Z axis drive ate it, potentially from the current being drawn holding the head up.  So until I get the new motor and drive, I won't be doing any cutting on the machine.
> View attachment 257209
> 
> 
> I have started the design work for the tool changer and have plans for a pneumatic cylinder, so hopefully those will be next.  I am also getting the planning for the enclosure started.  I got used to it with the X2 and doing the manual machining made such a mess I don't know how long I will last without one.


To take some strain off the Z-axis system you might install a couple of pneumatic cylinders, one on each side for balance. The regulator would maintain the same force through out the travel range. Mount the cylinders rod up to get maximum force from the piston. This is a common system  on industrial CNC machines that carry much heavier loads.


----------



## Larry42

shooter123456 said:


> I made some new lock nuts and machined some spacers for the AC bearings.  I suspect some of the .008" backlash was coming from the bearings I was using and I don't think they were preloaded properly.  I made 2 piece nuts with screws that can be tightened to lock the nut down on the threads.  These are much better than the lock nuts that came with the ballscrews and in my opinion, they are better than the nylon lock nuts.  Since it was an M12x1 thread, I couldn't commercial nuts for it anywhere anyway.  They use 3 4x40 screws to lock and I cut the holes so there was just a little bit of space between the nuts when the holes are aligned.  I have always had trouble with the regular lock nuts occasionally loosening up and it has ruined parts before.  I am confident that these won't move once locked.
> View attachment 259216
> 
> 
> Here it is installed on the X axis with the new coupler on the motor.
> View attachment 259217
> 
> 
> I machined some spacers so I could preload the AC bearings as well.  That was pretty straight forward but I don't have any pictures of it.  Essentially I machined a bar to the right inside and outside diameter, then parted off 3 pieces, then super glued each to a piece of steel in the spindle, and faced it until it was about .05" thick.  Using the lock nuts, I can adjust the preload on the bearings without needing shims.
> 
> I have the tool changer mostly designed now.  It will be a little while before I am ready to start making parts for it, but I will start ordering stock and parts soon.  The plan is to use a Nema 23 motor, a deep groove ball bearing, some round linear rails, and a pneumatic cylinder to run it.  I think I will use an arduino to control the changer if I can figure out how to interface it with LinuxCNC.  The plan is to have several sensors checking each step of the tool change to ensure reliability.
> 
> The tool change will go like this:
> 
> Z axis return to home position (Home switch confirm head in position)
> Spindle motor off (Relay on spindle power to ensure spindle motor off)
> Tool changer move into position below spindle (sensor to confirm changer in position)
> Z axis lower tool to tool changer (sensor confirm head lowers to tool tray)
> Pneumatic cylinder release tool (sensor to confirm cylinder actuates)
> Z axis return to home position (home switch confirm head in position)
> Tool changer rotate to the next tool (sensor to confirm position of carousel and proper tool selected)
> Z axis lower spindle to tool (sensor to confirm head lowers to tool tray)
> Release pneumatic cylinder (sensor to confirm cylinder releases)
> Retract tool changer (sensor to confirm tool changer fully retracted)
> Z axis return to home position (home switch confirm head in position)
> Confirm new tool in spindle (not sure how I will do this yet)
> 
> Here is the tool changer with all of the covers removed.
> View attachment 259218
> 
> 
> Other side.
> View attachment 259219
> 
> 
> On the mill.
> View attachment 259220
> 
> 
> I used Fusion360s FEA to make sure the changer wouldn't deflect too much under the weight of all the tools.  It gave me a deflection value of .0002" at the worst position so I am confident the structure is strong enough.
> View attachment 259221
> 
> 
> With a vise installed, there will only be about 5.5" between the bottom of the tool holders and the top of the vise jaw.  I am considering a few alternatives such as adding a Z axis to the tool changer so it lifts up and out of the way when not in use, and the table can move all the way forward (closest to me) when changing tools, so hopefully it will be mostly out of the way.  I don't think it will be too much trouble though, since I don't plan to have any tools sticking out more than 2 inches, and I don't often work with parts sticking more than 3.5" out of the vise.  Im pondering the idea of some kind of quick release for the tool changer so I can lower the tool carousel out and remove it completely for when I work with taller parts.
> 
> If anyone has any ideas or suggestions, I am all ears.  I have never tackled a project like this and could use all the help I can get.


Some machines mount the tool changer separate from the head. Off to the side. The machine then transverses to the end of its (X) travel to pick up tools.


----------



## shooter123456

Larry42 said:


> To take some strain off the Z-axis system you might install a couple of pneumatic cylinders, one on each side for balance. The regulator would maintain the same force through out the travel range. Mount the cylinders rod up to get maximum force from the piston. This is a common system  on industrial CNC machines that carry much heavier loads.


That seems to be a common solution for this sort of problem.  That motor was swapped for a 1200 oz in stepper, then swapped again for a servo.  Now the motor is more than capable of moving the head.

I still considered going that way to relieve strain on the system and prevent unnecessary wear, but when I did the math, it wasn't really worth it.  The head weighs about 75 lbs with everything on it.  The air cylinders would only be able to counteract gravity, otherwise they would be pushing up against the motor and the head would be floating.  Not ideal. At 75 lbs, the head experiences 333N pushing down.  The ballscrew is rated for 9800N.  So really nothing to worry about there.



Larry42 said:


> Some machines mount the tool changer separate from the head. Off to the side. The machine then transverses to the end of its (X) travel to pick up tools.



I also considered doing that, but elected not to for a few reasons.  First, it takes up table space, which this machine does not have much to spare.  I think on the one I modeled up, to get 9 tools on the table, I lost 6" of travel in the X, then a little more to keep the tool from hitting the rack when it was cutting.  The other issue I had with that is keeping chips away from the tools.  I wanted to keep the tools up out of the way to keep them a bit cleaner and hopefully prevent chip build up from gumming up the works.

I am very close to done with a rotating tool changer that will be mounted on the column.  It is a very common design on industrial machines, so in theory it is a tried and true method.

I appreciate your input though for sure!


----------



## Larry42

shooter123456 said:


> That seems to be a common solution for this sort of problem.  That motor was swapped for a 1200 oz in stepper, then swapped again for a servo.  Now the motor is more than capable of moving the head.
> 
> I still considered going that way to relieve strain on the system and prevent unnecessary wear, but when I did the math, it wasn't really worth it.  The head weighs about 75 lbs with everything on it.  The air cylinders would only be able to counteract gravity, otherwise they would be pushing up against the motor and the head would be floating.  Not ideal. At 75 lbs, the head experiences 333N pushing down.  The ballscrew is rated for 9800N.  So really nothing to worry about there.
> 
> 
> 
> I also considered doing that, but elected not to for a few reasons.  First, it takes up table space, which this machine does not have much to spare.  I think on the one I modeled up, to get 9 tools on the table, I lost 6" of travel in the X, then a little more to keep the tool from hitting the rack when it was cutting.  The other issue I had with that is keeping chips away from the tools.  I wanted to keep the tools up out of the way to keep them a bit cleaner and hopefully prevent chip build up from gumming up the works.
> 
> I am very close to done with a rotating tool changer that will be mounted on the column.  It is a very common design on industrial machines, so in theory it is a tried and true method.
> 
> I appreciate your input though for sure!


I've got two CNC's with tool changers. One is a ride-along with 8 tools that is located just in front of the spindle. The other is mounted at the end of the moving gantry and holds 18 tools. It has a cover built in. 8 tools isn't enough. If an operator has to put a different tool on the changer, he has to be sure to have told the machine the diameter and length or bad things happen. I can see where adapting a manual mill to a tool changer in a way that wouldn't limit the table movement would add design complications. It could be done by having the tool carousel move into and out of it's tool changing location.


----------



## shooter123456

I got the tool changer mounted up.  I ended up ditching the gearbox because the motion was utter garbage, and the motor has plenty of torque on its own.  The spring loaded tool fingers are working as expected, and when I set the tool change height, it grabs to tool groove just fine.

I am now working on controlling it.  I am using an arduino to control the tool changer, and it will communicate with the machine controller through the serial port.  I am planning to a few different sensors to keep it working right, and a switching relay to prevent it from actuating when the head is down or the spindle is on.  I am also thinking I will put an accelerometer on the tool platter, so that if a tool gets caught, it can send an E-stop signal to prevent the head from either crashing down on the tool changer or pulling it up.  There is enough play that it can bend a fair bit before anything would be in danger of breaking.

It still needs some work, but it is cool to see it mounted and moving!


----------



## phazertwo

Nice progress!  I really like that it doesn't stop at each tool, that will really speed things up!

PZ


----------



## shooter123456

Unfortunately, there has not been a ton of progress in the last few months.  I have been using the machine to actually make stuff rather than just working on the machine.

I got started on the new enclosure and it is going about as I expected given that I have no experience working with sheet metal and minimal experience welding (I have welded one other time, and it went poorly, but got the job done).  The enclosure uses 1.5" square tube for the stand and 18 guage sheet metal for the rest of the body.  It will have a chip tray right below the machine that will allow the coolant to drain and it will slide out to be emptied.  I keep thinking about a chip auger, but at the moment there is no plan to add one.  I don't think it is really needed, but I think it would be super cool to have one and never have to worry about the chips.  I am planning to have a wash down setting for the coolant, so when I switch a solenoid, the coolant will flow to a few parts of the enclosure and spray down the mill.  Again, not really needed but I think it will be really cool.  With the machine still in the other enclosure, I don't have a ton of room to work on it, so I had to stack things along the walls to make room.  The insulation panels normally aren't there, but I ran AC to the garage and the door is insulated.  A few of them fell out when the door was opened.

Here is the enclosure as it was a few days ago.  The welds aren't great, but so far they are holding.  I have added the two back panels already, but no pictures of that.  The right side of the machine is pretty square, but the left side is noticeably off.  I am happy with it though and won't go through redoing the whole thing.  I used a few harbor freight tools to make it work.  Their FCAW welder, pneumatic sheet metal shears, seamer, and grinder.  I also have the chip chute and tray made, but I am still grinding them and making sure they won't leak.  












I also made a little thingadoo that holds an air solenoid to the side of the head for the air blast coolant.  It also plugs up the hole were the quill handle used to be.  Two birds with one piece of metal!  The wiring and air line will be routed better once the enclosure is done.  I am planning to add a sheet metal guard to the head and the wire will run through a cable track.
















Slow progress, but it is still progress.  Currently working on redisigning the electronics box, replacing some of the connectors, rewiring to clean everything up, etc.  I am getting close to finished with the design for the control panel which will probably come before the enclosure is finished.


----------



## macardoso

Looking great! Remember, you're supposed to be using this, not just building


----------



## shooter123456

macardoso said:


> Looking great! Remember, you're supposed to be using this, not just building


What is this "using it" you speak of?  Isn't the whole point for it to self upgrade until it wears out?


----------



## macardoso

shooter123456 said:


> What is this "using it" you speak of? Isn't the whole point for it to self upgrade until it wears out?


Spend enough time on these forums and you'll start to believe it too!


----------



## phazertwo

As always, looking great!  I'm really liking the enclosure.

PZ


----------



## shooter123456

Getting close to the end with the new enclosure.  I have finished up most of the weld work, got the front opening all framed up, got new sliding rails for the doors, resized the doors from the old enclosure for use on the new one, mounted the doors, siliconed the corners where there was no sheet metal overlap, fabricated the chip tray, and I am now working on cleaning it up and getting it ready for paint.  A few places will need body filler, but I am hoping the end result will look pretty good.  I am planning to add the flood coolant tank and plumbing after painting everything and getting the machine moved over.   The paint on the mill is looking pretty rough in some places, so the machine will also get a fresh coat along with the enclosure.  I am planning to do the machine and lower part of the enclosure in gray and the upper and inside parts of the enclosure in white.  I am picking white mostly because it will keep things bright inside.  

Here is the enclosure almost as it stands now.  There is a little chip chute to funnel the chips into the tray which will sit on tracks below it.  





Here is a look at the inside looking down.  The tape is there to help get nicer edges from the silicon.  You can see the chip tray below and the chip chute as well.  





Here is another view of the chip tray down below.  The tray will sit on sliders so it will be up a little bit higher.  The gap should be about an inch, so hopefully it will manage to contain the majority of the chips.  





Just another look at everything.  The doors mount to the .25" steel bars running across the top and bottom.  Half inch steel square tube frames up the left and right side of the opening to stiffen everything up a bit and get rid of the sharp edge from the sheet metal.  I am planning to add a piece of sheet metal folded over the bottom edge of the opening to protect that as well.  





I got a bunch of new connectors and such for the new electronics box as well.  The number of connectors needed really adds up quick... I am hoping it will be worth it when I don't need to deal with the complete birds nest of wires running every which direction currently.  

Right now I am thinking the control panel will be mounted up on the front right, then a tool rack and accessory rack will be mounted to the left side.  I got the casters in recently, so those will also soon be added to the frame.  

I thought I had pictures of the doors, but it looks like I do not.  I will be sure to take some and add them.  The door frames are made of aluminum and the windows are acrylic.  I will be making some handles soon similar to the ones on the new tormach enclosures.  There is still plenty of work to go.  Need to figure out the automatic lubrication for the machine, way covers, motor covers (and waterproofing for flood coolant), control panel, head cover, spindle pulleys, air routing and control, and touch probe.  I am sure that list will grow before I finish...


----------



## shooter123456

I got the enclosure all bondoed up and primed.  I had the darndest time getting my little HVLP touch up gun to spray the primer well, so I ordered a full size HVLP gun which made short work of priming.  Amazing what using the right tool for the job does... less work and better results.  I also got one of those sand paper flapper wheels and that cleaned up welds and edges without digging in and making more trouble the way a regular grinding wheel was.  

Here it is all primed up.  The top will be white, then the bottom will be gray.  I will added some sheet metal around the base to clean it up at some point.  I will also be adding an edge guard to the bottom of the opening to keep it from getting dinged up and cutting me.  You can also see pretty well how the rear opening isn't squared up right.  The pieces I will add to close the gap between the mill column and enclosure should hide that completely, so I didn't bother trying to figure out how to correct it.





Another angle.  You can see some of the sheet metal seams on the inside.





Chip tray primed up as well.  I spent a long time welding up all of the edges to hopefully keep it water tight for when I start using flood coolant. I will add a drain to it when that happens.  I am still toying with the idea of adding a chip auger so I don't have to bother emptying it.  It would be overkill and unnecessary, but it would be cool and convenient, which is a good enough reason for me.





Here are the door frames.  I was planning to paint these as well, but while cleaning up the surface, I really liked the brushed metal look.  Unfortunately, there are a few dings here and there (door material was from the scrapyard), so I may end up painting it to hide those blemishes.  I tried using my metal brake to snap the window acrylic, but that didn't go so great.  The edges are very jagged and there are a few cracks, but those are mostly hidden in the frame, so I will likely use them for a while. 





I am thinking the first job for the machine once it is in its new enclosure will be finishing up the parts kits.  I have done a large chunk of the work on these and I tell ya, small scale production is fun!  Trying new things and thinking of ways to speed up the process is very satisfying.  So who wants a parts kit?


----------



## phazertwo

Wow.  That enclosure is looking nice!  Parts kits are too!  With all the grumbling about ArizonaVideo not providing kits on schedule, you should be able to sell those babies!

PZ


----------



## shooter123456

I think I figured out how I can make some way covers for between the saddle and column.  I want something that would keep chips and coolant off of the ways and ballscrew, without collecting chips until it jams everything up.  The stock set up with the thick rubber sheet worked ok, but it collected chips, and kept getting bunched up so that any time I worked on something larger than 3" wide, the vise would rub against the cover until it ripped.  The according style covers seemed ok, except that they caught chips like crazy and were difficult to keep clean.  The ones on the Z axis also ended up tearing after the vise rubbing it too many times.  

What I really want is some of those sheet metal telescoping ways that you see on the real VMCs.  They seem to protect well, easy to brush off the chips that gather on them, and last a long time.  The problems is that bending and welding sheet metal covers like that so they slide well while not having excessive clearance requires skill and equipment beyond my capabilities.  I tried to come up with something that I can reasonably make that will work well.  Since I am a lot better at machining than bending and welding, I tried to stick to machining as much as I could.

What I came up with is basically aluminum blocks that slide on rails with a piece of sheet metal attached to the top.  This way I can closely control the clearance between the parts and control their movement.  The blocks will have little pins sticking out of them that will ride in the a slot of the adjacent block.  This way, when the first segment reaches the end of its length, the pin will reach the end of the slot and start pulling the next one.  Then when that one reaches the end, it starts pulling the next one.  When they go the other direction, the table will push the first all the way back in, then the second, the third, etc.  I will use either felt or rubber as wipers for the covers to keep chips from getting under them between the spaces.  The two end segments will be fixed to the saddle and the column.  I am planning to use "tight tolerance stainless round bar" from mcmaster for the rails.

Here is a picture of the top.






Here is a picture of the bottom.





I have also designed the covers for the X and Y axis motors.  The X looks very similar to the way Tormach covers their motor.  Its just a box that surrounds the motor to keep chips and coolant off of it.  The Y axis has a sheet metal box that mounts to the motor mount specifically to protect the motor, then a moving section attaches to the saddle that will protect the ways when the saddle is moved toward the column.  





Any thoughts, feedback or suggestions are welcomed and appreciated!


----------



## macardoso

I like the idea! Do you think the rods are necessary? If you already have the tongue and groove on the inside of the plates AND you are bolting to the saddle which has to move perfectly straight out, then I'd think it would keep itself straight?

If you do use the rods, I suggest you install small oilite bushings in the plates. This will get your rods running through much more smoothly and less likely to bind in the hole.


----------



## shooter123456

macardoso said:


> I like the idea! Do you think the rods are necessary? If you already have the tongue and groove on the inside of the plates AND you are bolting to the saddle which has to move perfectly straight out, then I'd think it would keep itself straight?
> 
> If you do use the rods, I suggest you install small oilite bushings in the plates. This will get your rods running through much more smoothly and less likely to bind in the hole.


I thought they would rotate around the pin too much without the rods holding them in place, but now that I think about it, they could only tilt forward, and they would be resting on the section in front of them so they can't tilt forward.  So maybe it can be done without the rods... Worst case, it doesn't work and the rods can be added after the fact.


----------



## shooter123456

I made the new Y axis motor mount and bearing block.  This one does a better job protecting the coupling from chips and coolant, but it comes at the cost of decreased access during assembly.  I also switch from the original bearing block with a flange to hold the bearings in place to a configuration where one bearing goes in on each side of the bearing and preload is set by tightening the lock nut.  It is 3 different parts and I used alignment pins so they will go together easily and line up perfectly.  I am hoping they also add a little bit of rigidity to the set up. 

Here is a lock at the mount with the bearing block closest.  You can see how the coupler will be completely covered from the top.  The enlarged portion on the back where the motor mounts will also mount a cover for the motor.  That will be made of sheet metal and should do a good job of protecting the motor connections from coolant. 





Here it is from the motor mount end.  I enlarged the holes that mount the bearing block to the base which will hopefully allow better alignment once installed.  The 4 larger holes here attach the motor mount to the spacer, then the smaller holes on the outside corners will be used to screw the motor on. 





Here it is from underneath.  It looks like there is more space between the parts because I did a very light edge break chamfer on them. The finish on the spacer isn't fantastic.  I left .01" after roughing with the insert end mills to clean up with a regular end mill, but it wasn't enough.  I am wondering if there is run out in the holders of those end mills, so they went in farther than they should have and then there wasn't enough to clean up after.  I will increase the stock to leave for those tools so hopefully things look better in the future.


----------



## vinnito1

shooter123456 said:


> I think I figured out how I can make some way covers for between the saddle and column.  I want something that would keep chips and coolant off of the ways and ballscrew, without collecting chips until it jams everything up.  The stock set up with the thick rubber sheet worked ok, but it collected chips, and kept getting bunched up so that any time I worked on something larger than 3" wide, the vise would rub against the cover until it ripped.  The according style covers seemed ok, except that they caught chips like crazy and were difficult to keep clean.  The ones on the Z axis also ended up tearing after the vise rubbing it too many times.
> 
> What I really want is some of those sheet metal telescoping ways that you see on the real VMCs.  They seem to protect well, easy to brush off the chips that gather on them, and last a long time.  The problems is that bending and welding sheet metal covers like that so they slide well while not having excessive clearance requires skill and equipment beyond my capabilities.  I tried to come up with something that I can reasonably make that will work well.  Since I am a lot better at machining than bending and welding, I tried to stick to machining as much as I could.
> 
> What I came up with is basically aluminum blocks that slide on rails with a piece of sheet metal attached to the top.  This way I can closely control the clearance between the parts and control their movement.  The blocks will have little pins sticking out of them that will ride in the a slot of the adjacent block.  This way, when the first segment reaches the end of its length, the pin will reach the end of the slot and start pulling the next one.  Then when that one reaches the end, it starts pulling the next one.  When they go the other direction, the table will push the first all the way back in, then the second, the third, etc.  I will use either felt or rubber as wipers for the covers to keep chips from getting under them between the spaces.  The two end segments will be fixed to the saddle and the column.  I am planning to use "tight tolerance stainless round bar" from mcmaster for the rails.
> 
> Here is a picture of the top.
> 
> 
> 
> 
> 
> Here is a picture of the bottom.
> 
> 
> 
> 
> 
> I have also designed the covers for the X and Y axis motors.  The X looks very similar to the way Tormach covers their motor.  Its just a box that surrounds the motor to keep chips and coolant off of it.  The Y axis has a sheet metal box that mounts to the motor mount specifically to protect the motor, then a moving section attaches to the saddle that will protect the ways when the saddle is moved toward the column.
> 
> 
> 
> 
> 
> Any thoughts, feedback or suggestions are welcomed and appreciated!


From personal experience, I haven't had  good experience with AL rubbing on SS because the AL ended up galling. I would suggest look at adding some sort of bushing to prevent this from happening. Although your contact area looks alot more than my previous failed applications, so the stress causing galling should be alot less. My practical experience found that if the stress was above 2-3 ksi, binding would result between the 2 materials.

Have you thought about 3D printing the covers. This would be less expensive and allow you to build a smaller scale to work details.Here are a few pictures my design of 3d printed way covers ( in blue) from my column build/linear rail conversion. The small prototype i've built seem to have promise, but haven't gone full scale. I know that I would have to cover them in thin sheet metal to protect the surfaces from hot chips melting into it. I've has decent luck with the printed material not wearing out too quickly but would considered it to have a finite life. . And it should be pretty easy to design mounting provisions for the wiper.


----------



## shooter123456

vinnito1 said:


> From personal experience, I haven't had  good experience with AL rubbing on SS because the AL ended up galling. I would suggest look at adding some sort of bushing to prevent this from happening. Although your contact area looks alot more than my previous failed applications, so the stress causing galling should be alot less. My practical experience found that if the stress was above 2-3 ksi, binding would result between the 2 materials.
> 
> Have you thought about 3D printing the covers. This would be less expensive and allow you to build a smaller scale to work details.Here are a few pictures my design of 3d printed way covers ( in blue) from my column build/linear rail conversion. The small prototype i've built seem to have promise, but haven't gone full scale. I know that I would have to cover them in thin sheet metal to protect the surfaces from hot chips melting into it. I've has decent luck with the printed material not wearing out too quickly but would considered it to have a finite life. . And it should be pretty easy to design mounting provisions for the wiper.


If I use the guide rods, I am thinking I will add one of the oilite bushings mcmaster sells.  That should keep it from galling.  I hadn't considered 3D printed covers as I do not have a 3D printer.  Maybe someday I will have one and I can consider going that route.


----------



## mcdanlj

shooter123456 said:


> ...I do not have a 3D printer.  Maybe someday I will have one and I can consider going that route.



Let me know if you have a design you'd like to try printed.


----------



## shooter123456

mcdanlj said:


> Let me know if you have a design you'd like to try printed.


That is a very generous offer, I appreciate it and will keep it in mind.


----------



## shooter123456

So the boss says "I have a job I think you can handle."

Got the machining for the handles finished.  I am not sure if I will keep them this long, but this is the general idea.  The end parts were machined on the mill and the middle is just 1.125" aluminum tube I found at the scrap yard.  They will just screw on to the doors.






Just sitting on the door frames.





A little long I think, they will probably need to be shortened a bit.


----------



## shotgun choker

How much for one of your enclosures


----------



## shooter123456

shotgun choker said:


> How much for one of your enclosures


I am afraid it would be prohibitively expensive for me to make one where I wanted to make a half decent hourly wage for the time I spent on it.  

Though materials were probably around $500 or so and the extra tools were in the $300 range.


----------



## shotgun choker

shooter123456 said:


> I am afraid it would be prohibitively expensive for me to make one where I wanted to make a half decent hourly wage for the time I spent on it.
> 
> Though materials were probably around $500 or so and the extra tools were in the $300 range.


It looks good shooter, be sure to show the finished product.


----------



## rwm

Gorgeous! I want a tour when you are finished!
Robert


----------



## shooter123456

I made some progress on the way covers over the weekend.  I had a little bit of trouble getting the sheet metal to cut right on the machine, but a little bit of tweaking and a few failed parts got them to cut well enough.  I had to slow the spindle way down, slow the feed way down, and turn off the mister and spray WD40 instead.  Otherwise, it was so gummy it was just kind of smudging the material out of the way.  The little side pieces were all made from scraps (The largest one was only 2.125x1.6) so it is nice when I get to use those little extra bits and not need to buy more material.  There are 12 of those in total with the shortest ones having a slightly different profile to match the ways a little bit better and hopefully keep chips from getting in from the front.  There will be .025" clearance between the sides of the cover sections and .05" of clearance along the top sheet metal sections.  The slot in the sheet metal parts is .01" deep and will hold a .0625" thick piece of rubber to dampen vibrations and serve as a wiper.  If I have trouble with chips getting in along the sides, they have some .025" rubber or felt that can be attached there and help keep it sealed up.  

Here are the side pieces.  They are .3" thick and have a .165" slot going down the sides.  There is a corresponding raised circle on the other side.  The top has 2 6x32 tapped holes to hold the screws that attach the sheet metal.  






Here are a few pictures of a quick dry assembly.  The sheet metal parts need to be cleaned up a little bit (that was also made from scrap yard material), get rid of the smudgy burrs and clean up the surfaces. 















Just need to make 2 more sheets and wait for a new 6x32 tap to get here.  Then maybe make a new part for reasons that need not be disclosed about the broken tap that is stuck in it.


----------



## rwm

Tapping #6's can be a challenge. I try to design stuff with #8 at minimum.
R


----------



## shooter123456

rwm said:


> Tapping #6's can be a challenge. I try to design stuff with #8 at minimum.
> R


I don't typically like going so small if I can avoid it, but even with the 6x32 screws, the button heads barely clear.


----------



## rwm

Got it. If I were closer I would bring you some fuming nitric acid and you could dissolve that sucker right out!
R


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## macardoso

Looking great! If these turn out to work really well, I may need to make a set for myself


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## phazertwo

Looking really good.  I'm excited to see how the way covers work.

PZ


----------



## shooter123456

I finished putting the way covers together and I am hopeful.  They stay together well look to fit pretty well too.  A few of the sheets aren't completely straight, so the spacing between each segment isn't uniform on top.  I may have to go with a more sturdy material if that turns out to be a problem.  There is always the option of remaking the sheets out of steel instead of aluminum.  The sliding action is good.  They index off each other correctly and as long as I slide them out and in straight, I had no trouble with them binding up.  Occasionally, one of the segments did pop out of the slot, so I am thinking the .025" shims will be needed on the sides to keep them centered up and prevent the parts from separating.  

One other thing I had not considered was the noise they would make when you open and close them.  It sounded a lot like those heavy wood blinds on windows that go *ClackClackClackClackClackClack" when you open them.  I have a feeling when I have the Y axis going at 500 IPM, that could get obnoxious.  If it does, I may stick a small rubber bumper or something in the slot to keep that noise to a minimum.  

Here they are in all their assembled glory.










You can see the slight clearance between the segments here.  Once I put the .025" adhesive rubber strips along the left side, that will be filled and should be kept uniform.





Here they are collapsed.  You can see the sheets bowing slightly downward on a few of them.  This creates the slightly larger gap between a few sheets.  You might also notice the topmost ones have a slightly larger gap than the rest of the sheets.  That would be because someone wasn't careful enough when he modeled it and made that gap too large...










I am thinking I will sand the sheets to a brushed finish, maybe around 800 grit sandpaper.  I don't want to make them shiny and then have them look rough as soon as a chip scratches them, but I also think they will wear better with a surface that slides easier.  

One step closer to getting this machine the way I want it!  It will soon be time to wrestle with the new electronics set up.  I am looking into building a new PC to control it.  I want to get rid of the big ol computer that has to sit next to the machine.  Hopefully something with slightly better performance that I can fit in a smaller package.  I was thinking of putting the control PC in the same box as the electronics, but the fear of noise interfering is pushing me to give it its own box.


----------



## Firstgear

get the aluminum teflon impregnated hardcoated.....they will slide much better....


----------



## macardoso

shooter123456 said:


> I am thinking I will sand the sheets to a brushed finish, maybe around 800 grit sandpaper. I don't want to make them shiny and then have them look rough as soon as a chip scratches them, but I also think they will wear better with a surface that slides easier.



I usually opt for a fine scotch-brite finish by making small circular scrubbing motions across the whole surface. It hides scratches quite well in all directions.


----------



## rwm

I get a very nice random finish on aluminum by using my random orbit palm sander (yes for wood.) 
Robert


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## shooter123456

I have been working on the 4th axis brake design while I figure out how to proceed with the machines electronics.  I built a new control computer, but I got the wrong type of hard drive for it... So there isn't much to do on that front until the new one gets here.

The brake is a simple pneumatic brake, similar to what you might find on a car.  It uses a 2 stage air cylinder to actuate, then is released by one stage that works in both directions.  I haven't decided what to use for a brake pad material, but perhaps some kind of rubber or plastic.  I will use oilite bushings and ground guide rods to keep everything aligned.

The cylinder is an adjusted version of the one used for the draw bar.  It should be able to get a few hundred pounds of clamping force which should be more than enough to hold the 4th axis in place.  Also, the brake disk is slotted because thats how they are on the race cars and they look cool.  Here are a few of the pictures designs.

Here is the whole mechanism.






Here is the brake with the cylinder extended.  It only moves about .1" to lock the 4th axis in place.





And here is the cylinder and brake by itself.  The design got a little more complicated than I intended, but it seems like it will work.


----------



## rwm

This looks like an awesome design. Another thing you might consider is to use a hydraulic mountain bike brake setup. It would be easy to build a cylinder to convert air pressure to a much higher hydraulic pressure with different piston sizes. You could also borrow the disc although the diameter may be too large for this application.






Hard to beat for $15. Very small . You could mount the air/oil conversion cylinder remotely to save table space.

Robert


----------



## pstemari

rwm said:


> Tapping #6's can be a challenge. I try to design stuff with #8 at minimum.
> R


6-32s are well known to be troublesome when tapping. The minor diameter is too small compared to the major diameter and the result is a weak screw and tap.

If you go to a 6-40 UNF you'll have less of a problem. 

Sent from my Pixel XL using Tapatalk


----------



## shooter123456

rwm said:


> This looks like an awesome design. Another thing you might consider is to use a hydraulic mountain bike brake setup. It would be easy to build a cylinder to convert air pressure to a much higher hydraulic pressure with different piston sizes. You could also borrow the disc although the diameter may be too large for this application.
> 
> View attachment 300919
> 
> 
> Hard to beat for $15. Very small . You could mount the air/oil conversion cylinder remotely to save table space.
> 
> Robert


I actually considered that a while ago, but a few things stopped me.  
1. I have never worked with hydraulics before and I wanted to avoid adding another new thing to an already complex (for me at least) project.
2. I read from someone who adapted a bike brake for his 4th axis (Simpson iirc) and he said the caliper needed a lot of work to get it to work well enough.
3. I figured it would take just as much time to figure out how to get the bike brake to work as it would to design my own.
4. I like designing and making my own parts as much as (or more than) the final result.
5. Space is limited and I couldn't tell if the brake would fit.

I think using one as a spindle brake might be a better fit.  It could help slow the spindle down faster if I want to speed up tool changes once the ATC is up and running.  

I appreciate the input!


----------



## rwm

Those are all good points. I have some experience with these brakes. As a point of information the caliper is about 1" x 1.5" x 2.5". The pads are removable. The motion seems to be fairly precise. To adjust the caliper location, you actuate the caliper so it is locked to the disc, then lock down the holding screws. Pretty simple. I wonder if the other guy was using a mechanical caliper which is less precise?
How large in diameter do you envision your air cylinder? Double action is a good idea. I assume the 4th axis will need substantial braking force to prevent motion by the cutting tool? I would be concerned that a narrow radius disc would not provide the needed leverage with either setup?
Robert


----------



## macardoso

shooter123456 said:


> Also, the brake disk is slotted because thats how they are on the race cars and they look cool.



Love the design justification 

Looking great!


----------



## shooter123456

rwm said:


> Those are all good points. I have some experience with these brakes. As a point of information the caliper is about 1" x 1.5" x 2.5". The pads are removable. The motion seems to be fairly precise. To adjust the caliper location, you actuate the caliper so it is locked to the disc, then lock down the holding screws. Pretty simple. I wonder if the other guy was using a mechanical caliper which is less precise?
> How large in diameter do you envision your air cylinder? Double action is a good idea. I assume the 4th axis will need substantial braking force to prevent motion by the cutting tool? I would be concerned that a narrow radius disc would not provide the needed leverage with either setup?
> Robert


I don't recall what kind of brake he was using exactly, but he actuated it with a small air cylinder and lever, so that may have been mechanical.  The thing that worried me is that any wiggle in the brake could lead to chatter in the cut.  

The cylinder I designed as a .75" bore, with .3649in^2 of usable surface area.  The brake disk is 4" in diameter and the center point of the clamp is at 3.5".  I am not positive how the physics there works (and my knowledge of the other physics is limited to 2 college classes, so it might be wrong as well) but my math says:

.3649in^2 * 2 * 100 PSI = 72.98 lbs
72.98 lbs * 4.45 (newton conversion, this could be wrong) = 324.8N
Coefficient of friction for aluminum on aluminum is 1.05 (may not need a pad in that case, not sure) so 324.8 * 1.05 = 341N
1.75" (radius of brake disk at center of clamp) = .0445 m
341N * .0445m = 15.2Nm

I am not sure if tangential cutting force is the correct force to use to determine how much force the machine must resist during a cut, but even the heaviest cuts I might take were around 20 lbs of force.  Guessing the largest part I might work on is 4", that translates into 4.5Nm of torque.  

I am not sure how much the thickness of the brake disk will play into the equation since all it does is translate the holding force from the brake to the spindle.  As long as the force isn't so great that it crumples, I figured it would suffice.


----------



## rwm

It's been a while since college physics but I think your numbers are correct. 9.8 m/s divided by 2.2 Kg/Lb = 4.45. I doubt the disc thickness would be any issue since the forces are well aligned tangentially. I am pretty sure without doing any math that the tangential forces of cutting could exceed 20 lbs and would likely be in the range of 2000 lbs or more! I think milling generates some serious side loads. Am I off base on this? I am not at all sure that air pressure will hold the axis. I love this project!
Robert

Edit: OK maybe 2000 lbs is a stretch. I was trying to say that the force on the work piece can far exceed the infeed force especially if the tool binds in the work. I am sure we have all had work ripped out of a well tightened milling vise!

I realized one astute point you made above. "any wiggle in the brake could lead to chatter in the cut." The bike brakes do have some slop in the axis of rotation. They are not designed to resist rotational forces that alternate like you might see in milling. I think this would be an issue. Your 4th axis brake will need minimal travel to actuate it but a lot of force. Perhaps you could go with more stages and larger pistons? You could also go with small hydraulic piston and then use a converter cylinder with air to achieve any force you want. Basically like power brakes on a car that convert vacuum to hydraulic pressure. 
Robert


----------



## macardoso

rwm said:


> Am I off base on this? I am not at all sure that air pressure will hold the axis. I love this project!



I think you are correct. A test slotting cut I recently did (1/4" 4F roughing endmill, 1/4" deep, 25 in/min, 1.5HP) measured table thrust forces at roughly 500 lbs.  This was definitely one of the hardest cuts I have taken but this machine could probably push even harder. My machine is a CNC'd G0704.

EDIT: This number would have included the minor losses from the ballscrew and the substantial losses from the friction in the dovetail ways.

Since you only need small travel, why not place the cylinder at one end of a lever and the brake pad near the lever pivot?


----------



## matthewsx

Hydraulics are fairly easy to deal with. I would think an air actuated hydraulic cylinder would be fairly simple to construct. 

Look at racing go-kart brakes for a high performance relatively low cost solution. 

Cheers,

John


----------



## shooter123456

After seeing someone by the name of CNC4XR getting some new C5 ground ballscrews for his machine, I have followed suit and ordered ground ballscrews.  The cost was very reasonable and the quality looks good in the pictures I have seen.  Lead time is supposed to be about 2 weeks.

Besides the potential slight increase in accuracy over my current C7 screws, I am hoping they will rotate more smoothly than the rolled screws I am using, and ideally they will be straighter.  I also hope to get slightly better backlash with the new screws.  I also upsized the Z to 20mm.  I think it is overkill, but that will let me use larger bearings in the end blocks which should improve rigidity a bit. 

If other people have considered doing the same, here is the price info:
C5 ground ballscrew - 16mm - 5mm lead - 750mm length - BK12 end machining - Double nut - $172.08
C5 ground ballscrew - 16mm - 5mm lead - 350mm length - BK12 end machining - Double nut - $112.56
C5 ground ballscrew - 20mm - 5mm lead - 600mm length - BK15 end machining - Double nut - $148.96
Shipping and fees - $98.00
Import tax (Estimated) - $19.50
Total: $551.10

I will be sure to update when they arrive.


----------



## macardoso

Be interested to hear how these turn out. Mine are from Roton and are very sub-par. I have wanted to buy import ground screws, but heard too many bad stories of bent screws and off axis machining to feel like it was worth it.


----------



## shooter123456

New ballscrews arrived!!! I have to say, the difference between this set of screws and the first one I got is like carbon black and the surface of the sun.  Ok that might be a bit of an exaggeration, but this time I am happy with what I got while last time I was disappointed. 

The company I ordered from delivered everything as promised and everything was correct.  I was quoted a 15 day lead time from the time of payment, and I received my screws 16 days from payment (close enough for me).  All 3 screws were the correct length, correct pitch, correct nuts, and correct end machining.  I measured all 3 screws bearing and coupler diameters, and checked runout on the Y axis.  I got the following numbers: (all measured using a 1" micrometer that in theory measures to .0001")

X Axis:
Bearing Journal Diameter - .4718" (.0006" undersize)
Coupler Diameter - .3935" (.0002" undersize)

Y Axis:
Bearing Journal Diameter - .4718" (.0006" undersize)
Coupler Diameter - .3934" (.0003" undersize)
Bearing Journal Runout - Barely above .0005"
Coupler Runout - Slightly above .0015"
Front Nut Runout - Slightly below .001"
Rear Nut Runout - .0015"

Z Axis
Bearing Journal Diameter = .5890" (.0015" undersize)
Coupler Diameter - .4709" (.0015" undersize)

I really can't find anything to complain about there.  Screws seem straight as far as I can measure, end machining is well centered, fit with the ballnuts is excellent, finish is shiny, rotation is smooth and silent, what more could I ask for?

Have a few pictures!

They were shipped in a sturdy cardboard box and suspended using foam inserts.  They were well supported and seemed like they could take a solid beating without any damage to the screws.  Much better than the flimsy box and bubble wrap the first ones were sent in.  The screws were nicely oiled, had protectors covering the threads, and were wrapped in plastic bags that were taped at the ends.






Those ground threads are just pretty to look at.  And they look thicker than my rolled screws of the same diameter.





In case you were wondering how I measured the runout, here is how.  I used v blocks to hold the screw while using a dial test indicator to measure the movement as I rotated the screw.  The v blocks are sitting on my surface plate.  The indicator base is sitting on the counter top, which I know isn't ideal, but I think it is good enough.  





Comparison between the new and old screws.  You can see the nut on the ground screw is longer than the rolled screw.  I also like the look of the ground screw much more.





The only thing I don't like is that the screws have no preload.  Initially I thought the manufacturer messed up, but I think this one was my fault.  The invoice had "P0" in the product number for each screw which I should have clarified before purchasing.  I am pretty sure I specified no preload because of this.  As you can see, the spacer is only touching one of the nuts, and this is the case for all 3 of them.





All in all, I am happy.  Total cost was $531.60.  I thought there would be an import tax, but as it turns out, you don't need to pay an import tax on goods for personal use worth less than $2500.  So no tariff!  I am going to need to add some shims to preload the screws, but at this point I see no reason these won't be a huge improvement.


----------



## shooter123456

Since I had the mill apart, I decided to test the flatness and contact of some of the bearing surfaces.  I had some mixed results, which are far from scientific.  The X and Y axes seemed pretty good, but the Z was questionable.  Contact on the spindle, collet, and toolholder wasn't good at all.  I am not sure how I will deal with that.  Probably a new collet to start, then see where I am.

Here is a look at the top of the X axis ways on the saddle.  I blued the surface plate and rubbed the ways against them to check for transfer.  I see good contact on most of the surface.










The Y axis looked very similar, but I guess I don't have a picture of that.

For the Z axis slide, it looks like I am only getting contact on the outside of the oil slot.  I stoned the surface lightly to remove any burrs and there was no improvement.  For the record, this one was done first, so it wasn't the result of the prussian blue getting too thin and not transferring.  If anything, I had the dye on a little bit thick.





It is a little tough to see, but here is the blue transfer from the spindle.  I blued up the spindle taper, then drew the collet up with the drawbar while a tool was in it.  I torqued it down well, then loosened the drawbar and tapped it out and removed the collet.  The only dye transfer was around the sides of the slots in the collet.  





Again tough to see, but I did the same thing with dye on the inside of the collet.  The transfer to the tool holder was only around the cut slots.





So its a mixed bag there.  I will be looking into how to improve that in the near future.


----------



## mcdanlj

shooter123456 said:


> The company I ordered from



Do you mind sharing a link? ☺


----------



## shooter123456

mcdanlj said:


> Do you mind sharing a link? ☺


Their website isn't particularly good, but the company is called "Changsha Terry Machinery Co" and this is the link: http://terry-machinery.com/

I spoke with Sophia at sophia@ntl-bearing.com and she handled the quote, arranged shipping, etc.


----------



## rwm

Looks great. Thanks for sharing. I will be needing this for my PM728 conversion!
Robert


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## macardoso

Shooter,

I'm honestly very impressed by how good your contact is on your ways. I don't have pictures to share, but take my word for it that my G0704 was much worse! I have similar contact on my spindle to collet. I have also noticed that probably 80% of the grip on my tool holders happens on the first 1/4-3/8" of the tool shank (nearest the end of the spindle). I have a feeling this drastically reduces holding force on the tool.

Mike


----------



## macardoso

shooter123456 said:


> Their website isn't particularly good, but the company is called "Changsha Terry Machinery Co" and this is the link: http://terry-machinery.com/
> 
> I spoke with Sophia at sophia@ntl-bearing.com and she handled the quote, arranged shipping, etc.



How the heck did you find these guys?


----------



## shooter123456

macardoso said:


> How the heck did you find these guys?


A guy I follow on instagram got ground screws from them.  I slid into his DMs and asked who he contacted and he was happy to share.  His instagram name is "CNC4XR"


----------



## shooter123456

macardoso said:


> Shooter,
> 
> I'm honestly very impressed by how good your contact is on your ways. I don't have pictures to share, but take my word for it that my G0704 was much worse! I have similar contact on my spindle to collet. I have also noticed that probably 80% of the grip on my tool holders happens on the first 1/4-3/8" of the tool shank (nearest the end of the spindle). I have a feeling this drastically reduces holding force on the tool.
> 
> Mike


Note that the blueing is only checking flatness of the ways, not necessarily contact between mating parts.  If they grind the top surface well, I imagine getting them flat isn't too great a feat.  It could be partially due to wear, but I think I attribute much of it to decent build quality.  

I am wondering if the poor contact on the taper, collet, and tool is related to poor grinding and poor fit of the parts.  I imagine if there is that little contact, there can't be much friction which would result in poor tool retention.  I can get tools to pull out with a 3/8" end mill with .5" DOC and seemingly light cuts.  I can't push MRR up much past 1 with a standard end mill.  With insert cutters I can get much higher.  I would like to get that sorted out before adding more springs and a stronger air cylinder to keep tools in place during heavier cuts.


----------



## shooter123456

I have most of the things I need together to get the new electronics box going.  This time I tried to make sure I had all my ducks in a row and had sufficient quantity and quality of parts to make sure everything works reliably for a while.  I got some proper disconnect switches to control power to the machine, terminals, terminal blocks, cable glands, cable tubing, crimping tools, power distribution blocks, etc. 

Here is most of the stuff that will be in the electronics box. (Minus the dish soap and sponge, that will stay in the kitchen)






There will be 2 power supplies.  One shows some corrosion because it spent some time powering an LED light above my old saltwater fish tank.  That one is 48v and will run the 4th axis and tool changer stepper motors.  The other is a 5, 12, and 24v power supply that will run most of the extras.  Then there are 2 parallel port breakout boards which will handle the interface with the computer.  Those should have more than enough IO for the machine. Above those is a relay board with 8 relays.  That will control the draw bar, the tool changer air cylinder, spindle enable/disable, 4th axis brake, air blast solenoid, mist solenoid, and flood coolant pump.  That leaves one more for something I am sure I am forgetting.  Above those are the 2 stepper drives for the 4th axis and tool changer.  At some point I might get some Clearpath servos to replace those steppers, but for now, I have steppers and I would like to put them to work.  To the left of the 48v power supplies is the power distribution blocks.  I found those on Mouser and they are inexpensive and pretty awesome in theory.  They have adhesive backs to stick them to the electronics box surface and the big ones can handle insane power in theory (Something like 600v at 40 amps if I am remembering right.  Don't quote me on that).  Those will distribute the 120v line, the 240v line, and the multi voltage power supply. 





I picked up these disconnect switches from automation direct and I was thrown by the size of the knobs... I was not expecting them to be so massive.  The switches are rated at 600v/20 amps each.  One for the 120v line and the 240v line.  I feel like there is a way to use just the 240v line and convert it to 120v inside the electronics box, but I couldn't figure that out with a few hours research, so I decided to just have 2 input lines.


----------



## matthewsx

I have a step down transformer I'm planning on using to convert 240v to 120v. You can also just break out one leg from the 240v but you will need the neutral so probably a 4 wire cable to run from the mains. I have both voltages running into my existing control box but it would be nicer to just have one plug.

Looks good, I've got to get going on my new electronics box now that I have my Y axis fixed (new ballscrew)

Cheers,

John


----------



## mcdanlj

shooter123456 said:


> I feel like there is a way to use just the 240v line and convert it to 120v inside the electronics box,



In the US, 240V is two opposing phases (technically, "legs") of 120V each, and 120V is one of those phases against neutral instead of against the other phase. Your breaker box has both phases and your 120V circuits are some on one phase and some on the other.

Neutral is tied to ground at your main circuit box, but never use ground for neutral.

You can use a NEMA 14-30 straight or L14-30 twist lock to carry ground, neutral, and both phases. This requires running 3 conductor plus ground wire from the breaker to the outlet. This is a normal cable, nothing special. 10/3 W/G will I believe support 30A intermittent load which I would expect is fine; 8/3 W/G for continuous which I doubt you need on a mill that shipped to run off of 20A 120V intermittent or maybe even just 15A? You can ask an electrician, this is just my expectation not a qualified opinion

(Technically, this is single phase power, and the two legs are the same phase, inverted. The point is that while one leg is positive, the other leg is equally negative, and they swap roles 120 times per second, for complete cycles 60 times per second, which is our 60Hz main grid power.)

You could then use a single three phase e-stop for the two opposite hot wires and the neutral wire.


----------



## macardoso

Looking great! 

Your home utility is 240V where both legs are hot relative to ground. At the utility panel, a neutral wire is connected to earth ground and each leg of the 240V to neutral measures 120V. This is how all the outlets in your house work. The good news is this, if you bring the 240V into your cabinet with a neutral and ground wire, then you can tap one leg of the 240V and the neutral to get 120V. This is fine by NEC code. Try measuring it with a multimeter to prove it to yourself. 

The only word of caution is that if you pull a lot of current (think 10A) on the 120V leg, then the current draw on your 240V will become imbalanced. This isn’t dangerous but if you protect your 240V line with a 20A breaker then it would trip sooner than expected.


----------



## macardoso

Whoops! Someone replied at the same time as me. 

Looking at your pictures, I see a lack of circuit protection. This is an extremely import part of building circuits and is required by code. Now I’m sure many here don’t build to code, but on a personal level you don't want you cabinet catching fire or damaging your electronics if something goes wrong. 

Doing this stuff is part of my day job and I’m happy to help if you need thoughts on circuit breakers and wire sizing.


----------



## mcdanlj

One more detail: if you have 240V options for power supplies, and you are running 240V anyway, use 240V everywhere you can. @macardoso 's point about unbalanced legs is one reason, but there is another.

W = V²/Ω = ΩA² and A=V/Ω so power increases as the square of the voltage but current linearly with voltage.

Power makes the machine go, and current heats the supply wire.  So a (say) 2.2kW spindle, at (say) 85% efficiency, would consume about 2.6kW of electrical power. 2.6kW/240V = 10.8A which would dissipate 117W per Ω in the supply wiring. 2.6kW/120V = 22.6A which would dissipate 470W per Ω in the supply wiring, 4 times as much.  You can probably see a reason why the rest of the world, more or less, uses 220-240V power. It requires less copper. Thicker copper, lower resistance per foot. That resistance has a smaller proportional loss at a higher voltage, all other things being equal.

Hope that's useful...


----------



## macardoso

mcdanlj said:


> One more detail: if you have 240V options for power supplies, and you are running 240V anyway, use 240V everywhere you can.



I forgot to mention that entirely! I use 240V for everything in my cabinet except for two small accessory outlets on the side of my panel for 120V devices like lamps or coolant pumps. It is just easier that way.

Also if you have a 200V class servo drive and you power it with 120V, you cannot get the rated speed on the motor (even if the drive is OK with 120V)


----------



## shooter123456

There hasn't been a ton of progress on the machine recently.  I have it mostly reassembled in the new enclosure and I am working on getting everything wired up.  I am going to redesign the motor mounts once more since I got larger bearings for the ballscrews and the current design won't work just right with them.  

I managed to get the axis motors wired up and with the 75v power supply, I was able to achieve 600 IPM on the X and Y.  The ballscrews didn't seem to like it though (old rolled ones, not the new ground ones) and I will probably drop that down to 300 or 400.  The Z was stalling out around 350 and will be kept in the 250 range.  

I got the cable carrier mounted on the Z and while I don't love how it is on there, I don't see another decent alternative.  The spindle motor cables are so beefy that tighter loops just aren't going to happen and when spinning the connectors around the other way, the cable chain would need to be mounted so high it was ridiculous. 

I apologize for the picture quality.  There is dust under the glass in my phones camera so most of the pictures look a little hazy now.  I had to take apart the connectors to get the cables to fit through the carrier, so it will be a while before I change anything on it again.  I will say though that those M23 connectors are much nicer than any of the other ones I have used.  






Macardoso, I have overlooked circuit protection.  I have always assumed that the circuit breaker on the house and the internal fuses on the nicer electronics were enough.  In the past, none of my electronics were worth enough to worry about adding extra protection, but now some of them are.  Would would you recommend adding for further protection?  I would like to at the very least protect the clearpath motors, the clearpath power supply, the spindle drive, and the control computer.  I am currently using 12 AWG cable to connect the wall power to the electronics box, then I mostly stick to 14 AWG for anything carrying power, or whatever the specific manufacturer recommended. 

Also, it has probably been a while, but you helped me set up the spindle drive when it arrived and we covered the 120v vs 240v performance quite a bit.  I am thinking for my next machine (or next iteration of this one) I will try to get everything I can on 240v.


----------



## macardoso

So, circuit protection is mostly to protect the wires, not so much your components. You have to imagine that if you were to short two terminals anywhere in your cabinet, where are wires going to melt. Typically you'll have one big main breaker in your cabinet (that should trip before the breaker in your home's breaker box) and several smaller breakers/fuses for individual components. You CAN get around using breakers if you run wire large enough to carry the entire panel's Full Load Amps (protected by your house's breaker), however this can get expensive and is not necessary. 

At 12AWG, you need to make sure your house breaker is not more than 25A. Again this is all to make sure your panel doesn't start a fire or melt your wires.

If a component is going to fail, it is unlikely that your upstream protection is going to help save that device at all, however it can protect upstream components. 

If you send me a sketch of your circuit, I'd be happy to help recommend where you should have breakers or fuses.


Awesome work as usual! You keep me motivated to keep working on mine!


----------



## mcdanlj

I'm a programmer, not an electrical engineer, so I write with trepidation, but... When it comes to circuit protection the question is which risks to what components are you protecting against. *TL;DR:* a circuit breaker or fuse protects against things melting when there is a downstream short circuit or otherwise drawing enough current to melt wires upstream. Note that this is not particularly effective for protecting downstream components; there's not much a circuit breaker will do to protect your clearpath motors. For that, you need transient voltage suppression.

There are two classes of circuit protection, basically: over current and over voltage. Circuit breakers are over current protection. Excessive current produces excessive heat, and over current protection protects against effects of heat, up to and including fire. Your home circuit breaker protects the wires in the walls. If you have thin wires connected to the outlet at a gauge that might be damaged or catch fire before tripping your home circuit breaker, they should be behind a smaller over current protection device (fuse or circuit breaker) so that there is a breaker that trips before those wires melt or catch fire.

A GFCI is basically a very sensitive over current protection device that trips if it measures any current to ground, as personal protection against electrocution hazards. 

A circuit breaker basically does nothing for over voltage protection (except in as much as sustained over voltage causes over current), and to protect your motors you want over voltage protection as well as over current protection.

There are basically three ways to protect against over voltage: shunt it through a temporary intentional short circuit (a "crow bar"), do something to limit exposure of a sensitive circuit component to a high voltage by filtering it, or sense and interrupt the circuit (effectively a circuit breaker, but not what we normally mean by "circuit breaker"). You probably care only about the first two. (AFCIs are kind of a special kind of filter-triggered circuit breaker that is tuned to a particular kind of noise associated with arcs, which is why they can be annoying with physically commutated motors, which can be annoying in the home shop.)

The surge suppressors you can buy cheaply use devices called metal oxide varistors (MOVs) which are basically insulators at normal voltage but conductors at high voltage. These are shunt devices. They are available with different voltages and energy dissipation capacity, and usually fail short circuit (unless they are blown to bits), so they need a circuit breaker or fuse "upstream" to protect against over current if they fail short. The goal here is to protect equipment from a large increase in voltage. My understanding is that typically heavier-duty (can absorb more energy) MOVs are less sensitive, so it's not that unusual to have a whole-house surge suppressor installed on the main panel, and individual surge suppressors on sensitive equipment. At DC component levels, and especially at signal levels, TVS (transient voltage suppression) diodes are common shunt devices. They are available with a wide range of "breakdown voltages" at which they start to meaningfully conduct. They provide a similar benefit, and I think typically respond faster than MOVs, but carry less energy. (They are available in bidirectional versions that are appropriate for AC signals as well as unidirectional versions appropriate for DC signals.)

The line between filtering and shunting can be blurry. A resistor and capacitor can be seen as shunting a transient spike or filtering a high frequency signal, and it's really the same thing. But an inductive filter in line (including ferrite cores) is only a filter and not a shunt. An inductive filter limits the rate of change of a signal going through it; you can think of change of magnetic field having inertia. So an inductive filter can both protect against noise and relatively low, short voltage transients, and so is mostly useful for cleaning signals of signal-level transients rather than damaging voltages, as I understand it. @macardoso has been using ferrite beads for signal cleaning recently. ☺

I don't know if that's interesting or useful. Others here can chime in with more informed help than I can.


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## rwm

mcdanlj- Very helpful in my understanding of this!
Robert


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## macardoso

mcdanlj said:


> I'm a programmer, not an electrical engineer, so I write with trepidation, but... When it comes to circuit protection the question is which risks to what components are you protecting against.



Awesome explanation, thank you! From my experience in the industrial automation sector, there typically is not any surge protection installed on equipment except what is already present in the devices being installed. Overcurrent protection is required by code (NEC, IEC, etc.) and is installed everywhere. I have installed surge protection on a small number of panels, but these were specialty applications which were very different from your average factory.

If your concern is about the Clearpath motors, it is likely that the only thing which will be damaged in the event of a lightning strike would be your power supply. I find it unlikely the motors would sustain damage (power supplies typically protect the output in the event of failure). Lightning strike is quite rare so I wouldn't worry yourself too much! 

-Mike


----------



## mcdanlj

macardoso said:


> From my experience in the industrial automation sector, there typically is not any surge protection installed on equipment except what is already present in the devices being installed.



I think most industrial automation would have on-site transformers down to 480/240V with the downstream not particularly exposed to risk of lightning, and the transformer is a massive inductive filter. Whereas practically all residential power shares a stepdown transformer between multiple houses and in some places that's above-ground, so more exposed. I don't know, though; does that make sense?



macardoso said:


> Lightning strike is quite rare so I wouldn't worry yourself too much!



Down here in our part of NC (@shooter123456 and I live near each other) there's a lot of overhead last-mile power, and anecdotally the incidence of lightning damage seems higher here than in MN and WI where I grew up, where most of the 240V power distribution is buried. I don't know whether that's supported by data and honestly don't know where I would look. My current neighborhood has buried kV-range (I think) distribution, but my previous neighborhood had 240V on poles everywhere and power wasn't very clean. I think that a few decades ago it was substantially more expensive to bury cable in the heavy clay here than in the loam and gravel I grew up with. Even so, my parents in WI, with all below-ground feed from their upstream transformer to any of the houses it feeds, have had two lightning events that have damaged electronics over the past two decades, in both cases from lightning strikes on their property. There's anecdata for you! 



macardoso said:


> I find it unlikely the motors would sustain damage (power supplies typically protect the output in the event of failure)



I certainly agree, unlikely. In the realm of unlikely, I would assume that the first thing to go would be the encoders on the motors, not the coils in the motors.

Are the power supplies fully isolated?

Anyway, a surge suppressor can absorb only so much energy, but it's relatively cheap insurance that protects against at least some borderline cases. If you are in an older neighborhood with overhead power, I think it's worth it. (I have whole-house and individual surge suppressors, even with underground delivery from the transformer maybe 50 feet away, but that's probably overkill.)


----------



## macardoso

Well, I've never heard of anyone who has had as many issues with lightning as you, but I guess if I had, I'd be worried about surge protection too!   

Thanks for sharing, I definitely learned something.


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## rwm

Here in the CLT all the lines are overhead and we have some bad electrical storms. It is common to have strikes with 1/2 mile from my house. I am surprised I have not had a major issue yet.
Robert


----------



## shooter123456

I have made some progress recently!  Things are coming along.  The machine is all wired up, everything is back together, and it is making chips again.  There is still plenty of work to be done, as usual, but it is alive and kicking.  

Here is a quick look of the electronics box while it was still being wired up and still looked somewhat clean.  The spindle drive and the servo power supply are both mounted outside the control box.  The large 48v power supply will be used to power the steppers for the tool changer and 4th axis.  I have not decided yet how I will control the tool changer, but I added the second breakout board for the extra IO just in case I wanted to run it directly from the control computer instead of going through a separate micro controller.






Here is the repurposed spindle control box that came mounted on the head originally.  The top switch is the 240v input and the bottom is the 120v input.  It works just fine and I like being able to cut power easily with the switches. 






The chip containment on the enclosure is excellent.  The chip chute and chip tray are working exactly as I had hoped.  The only place I have chips escaping is occasionally out the top.  It isn't enough for me to worry about it though, so for now I won't make any changes to that.  Here is a top down look at that.






Chip tray full of chips on slides.  Just slide it out and scoop the chips into a bin.  I still want a chip auger though... 





Here are a few more pictures.















I also had a shop visitor one day.  He showed up on a particularly cold day, probably just looking for somewhere warm.  I wasn't running the machine that day so luckily, he did not get hurt.  I have not seen him since though...  





I am working on making new X, Y, and Z motor mounts now so I can mount the new ground ballscrews.  I got some larger bearings and the new mounts will protect the motors and couplers.  

I will also be adding some circuit protection just to be on the safe side.  I think the enclosure could use some stiffening, so I will be welding some more next time the machine is out.  Overall, I am happy with how it is working.


----------



## rwm

This is great! Love the sliding doors and the chip tray. Looks like a commercial machine like a Haas! (Love the lizard also. We have them)
Robert


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## macardoso

Looks amazing! Love the enclosure. I *need* to build one soon.


----------



## phazertwo

As always, great work.  Love seeing what you come up with!

PZ


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## macardoso

Am I crazy, or does it look like the enclosure is open on either side of the column? Would it not throw chips out the back?


----------



## shooter123456

macardoso said:


> Am I crazy, or does it look like the enclosure is open on either side of the column? Would it not throw chips out the back?


Not crazy, the enclosure stops just short of the width of the base in the back.  This was meant to compensate for the lack of welding and fabrication skill needed for a tight fit.  It was also done to keep the depth of the enclosure to 24".  Making it just 2 inches longer made the materials significantly more expensive and would require a lot more cutting.  It is sealed using heavy plastic (like a shower curtain) while I work on an adjustable sheet metal piece to seal it up properly.  So far, there haven't been any issues with chips escaping out the back.


----------



## shooter123456

I am almost done with the new hardware for the X and Y axes.  The goal was to protect the motors and coupler area better so they aren't always covered in chips.  This will also be more important when I add flood coolant.  The clearpath motors do not have water proof connections, so they can't be getting wet.  The new hardware protects everything on all sides except the bottom.  The new x axis will also have built in connections to supply power and air to the 4th axis (or pneumatic vise if I ever make something like that).  

I also have a hankering for a new spindle.  I think the current one could be much more rigid, smooth, and quiet.  I think something that causes less vibration at high speeds could significantly improve surface finishes.  I have been working on a design that would only require a little bit of modification to the current head to secure it.  The new spindle would have 3 bearings (2x 7007 for the bottom and 1x 6906 bearing for the top.  I am planning for around 10,000 RPM again, though hopefully much smoother running and no issues with pullout if I want to make heavier roughing cuts.  

The new spindle is a little bit narrow once it gets into the head.  That is to match the current spindle OD and avoid needing to make a new head or try to bore out the current one.











The new one will use 2 bearings on the lower end instead of just one, and they will be preloaded against each other.  The bottom of the spindle is also much closer to the bottom of the bearings compared to the current spindle.  Even with the flange and mountain adapter, the spindle sticks out slightly less.  





Here is the plan with the new X and Y hardware, as well as the new spindle in the head.  





I would be happy to hear opinions and ideas, especially if you see something that would keep this from working well.


----------



## phazertwo

NICE!  Looks like your going for a BT30 spindle?  Cut2Cut and I were discussing this about a month ago, so I'm super interested to see what you come up with.

PZ


----------



## macardoso

I'm really been toying around with a 10-12k rpm spindle for a benchtop sized machine. Did a lot of research and analysis. Was going to post on here at some point, but maybe now is as good a time as any. Would you like if I created a new post in the CNC projects area to specifically discuss the design? Maybe together we can come up with some compelling designs.


EDIT: Design Looks great BTW.


----------



## shooter123456

phazertwo said:


> NICE!  Looks like your going for a BT30 spindle?  Cut2Cut and I were discussing this about a month ago, so I'm super interested to see what you come up with.
> 
> PZ


Yes, I am thinking BT30 so I can have a pull stud for better tool retention and the much larger availability and variety of tooling.


----------



## shooter123456

macardoso said:


> I'm really been toying around with a 10-12k rpm spindle for a benchtop sized machine. Did a lot of research and analysis. Was going to post on here at some point, but maybe now is as good a time as any. Would you like if I created a new post in the CNC projects area to specifically discuss the design? Maybe together we can come up with some compelling designs.
> 
> 
> EDIT: Design Looks great BTW.


Sounds good to me, I am happy to share the design and the more input the better.


----------



## shooter123456

I am just about finished with the new hardware for mounting the new ballscrews and protecting the motors better.  I have a pictures to share. 

This is the new Y axis assembly with all of the guards installed.  This should keep the chips and coolant off the motor, bearings, and coupler.  






Here it is with the covers removed.  I anticipate it being much more rigid with the shorter and thicker risers and a thick motor plate, rather than thinner and longer risers attached directly to the motor.





Another angle.





This is the new X axis.  This one is also a little bit on the heavy side, but I relieved material everywhere I could to lighten it up.  The worst of it is the massive bearing block.  





This is the back side.  The part on the right will have the electrical connections for the motor (1 for power, one for signal) and the other 2 will be input for the 4th axis and a QD connector for output.  This way when I remove the 4th axis, I can just unplug it from the block and cover the connector.  The left side is for an air supply.  It will have input and output for 2 air connections.  One for actuating the brake, one for retracting it.  If I ever make a pneumatic fixture or pneumatic vise, the air supply could also be used for that.





Here is the inside.  Again it will be better protected and this design should be stronger than the current set up.  





All of the parts use pins to make alignment and assembly much easier, so the fit will be much better than my current design.  The pins may also add a little bit of strength to the set up as well.


----------



## rwm

I'm not sure where you are on your 4th axis but I ran across this video of a 4th axis brake. Not sure if you have seen it?






Robert


----------



## shooter123456

rwm said:


> I'm not sure where you are on your 4th axis but I ran across this video of a 4th axis brake. Not sure if you have seen it?
> 
> 
> 
> 
> 
> 
> Robert


I have seen that one, and it helped a lot with the design of my brake.  I had trouble replicating his design though, so I had to make some changes to mine to hopefully come up with something that works.  Right now, my 4th axis is finished, but the brake has not yet been started.  The list of projects only seems to grow...


----------



## shooter123456

I got some more work done this weekend.  I now have all of the mill operations done for the new hardware, down to just the lock nuts on the lathe.  I noticed I had several different generations of parts, and I thought that made for a good picture.

Each iteration has improvements on the last, so maybe 3 or 4 more and I will have something excellent!






The latest Y axis ballnut mount is thinner, has a smaller hole in the middle (I realized there was no reason to cut out a lot, the screw isn't going anywhere), has 2 bosses machined for alignment, and has a longer boss that goes into the saddle.










The new X axis ballnut mount is for a 20mm screw, also has 2 bosses for alignment, uses 1/4x20 screws instead of 10-32, has space for 2 screws to attach it to the head instead of 1, and has a smaller hole through the middle.





I also cut the ballnut for the X axis so it will clear the table.  It went surprisingly well and the finish was fantastic.  I did not think the machine would handle hardened steel as well as it did.










It mounts in the ballnut mount with 2 bosses for alignment and 2 10-32 screws to secure it.  This one is significantly beefier than the previous one, and will hopefully lead to a more rigid mounting.  The end hangs over a little platform on the saddle, so the ballnut hangs down a little bit past the bottom of the mount. 






Once the lock nuts are done and drilled, the mill can come apart and the new parts will go on!


----------



## rwm

That is some cool stuff! Very professional looking parts!
Robert


----------



## shooter123456

Almost there!  I got the lock nuts finished and did some test assembling.  The lock nuts are 2 pieces.  1 piece has a flange and holes for a wrench to be used when tightening, then 4 threaded holes for screws to lock the second nut into place.  The first nut also acts as a spacer to reach past the flange holding the bearings into the bearing block.  There is also minimal clearance between the nut and the flange to minimize the amount of space for chips to get into the bearings if they get past the covers.  I have found this sort of lock nut to be very effective, even slightly tightening the screws into place (like rolling the allen wrench between your fingers to tighten) makes it nearly impossible to remove the nuts by hand.  

I have 2 for the 16mm ballscrews and 1 for the 20mm screw.  I am unsure what caused the browning on the nut in the middle.





Here is how they assemble on the ballscrew.  The longer nut is relieved so the end can go over the unthreaded portion of the ballscrew and tighten against the bearings.





Here is a view of that from the side.  I am happy with how that fit turned out.  Things don't always come together so nicely when assembling.





Here are the bearings installed in the Y axis bearing block with the flange installed as well. 





And then the ballscrew installed with the lock nuts in place.  





It will be time to pull apart the mill and put all of the new parts on very soon!!


----------



## rmachinist

shooter123456 said:


> How to remove the Z axis leadscrew on a PM-25MV mill.  (I couldn't find it by googling, so hopefully the next guy can find this)
> 
> It took me a while to get the Z axis leadscrew out because of the way the miter gears are installed.  Turns out, you need to remove it all in a pretty specific order.
> 
> Step 1. Lock the Z axis gibs so the head stays in place.  It might be a good idea to put a note or mark somewhere so you don't forget the leadscrew is out, then unlock the gibs and have the head fall.
> 
> Step 2. Remove the column cap.
> View attachment 256286
> 
> 
> Step 3. Remove the lock nut from the Z axis lead screw while holding the Z axis handle to keep it in place.
> View attachment 256287
> 
> 
> Step 4. Remove the set screw holding the smaller miter gear to the shaft.
> View attachment 256288
> 
> 
> Step 5. Tap the shaft out from right to left.  The Z axis handle will come out with it.
> View attachment 256289
> 
> 
> This is what that shaft looks like with the handle removed, but it does not have to be.
> View attachment 256290
> 
> 
> Step 6. Remove the large miter gear from the Z axis lead screw.
> View attachment 256291
> 
> 
> Step 7. Remove the key in the Z axis lead screw.  If you try to drive it out before removing the key, you will break a thrust bearing.  This is what the shaft looks like.
> View attachment 256292
> 
> 
> Step 8. Remove the screw from the Z axis saddle that holds the lead nut in place.
> View attachment 256293
> 
> 
> Step 9. Jiggle the lead screw until you get it to drop free, while holding the nut so you can lower it down.
> 
> Step 10.  Once the leadscrew is free, remove the 4 screws holding the handle plate in place.  Then pull straight out. There are roll pins in place so it can only be pulled straight out.
> View attachment 256294
> 
> 
> Step 11. While holding the nut from the front of the column, unscrew the leadscrew until it is free of the nut.  Pull the screw out and then pull the nut out.
> 
> Step 12. Nap time, cuz that was exhausting.


Will the leadscrew come out from the top? does the nut and gear need to be removed


----------



## HeavyMetal747

I really need to chime in on the ball screws. I'm going to sound like a real jerk here, but if one person believes me, it's worth it.

Did you blow up that picture of the ball screw? The o.d. is ground, but the actual threads are not. They are rolled. They are pitted. They do not have a good finish at all.

He didn’t check the thread lead at all. That is the only thing that matters. Most ball screws are going to have some run out.

With a solid set up it works itself out because the ball screw itself is flexible. With the threads in it, and the radius at the root of the thread, they flex. They have to or they would break.



A true ground C5 ball screw of any length cost $4000-$5000 dollars in the U.S.

This is because the lead of the screw is held to .0001” or less.  The O.D. size just doesn’t matter. The run out, to a point, just doesn’t matter.



I have spent hours upon hours upon days upon days looking and studying all of this, so I could have an intelligent conversation about it.

What you have seen is not a precision ground ball screw. It is a *******t way of telling you that it is.


----------



## shooter123456

HeavyMetal747 said:


> Did you blow up that picture of the ball screw? The o.d. is ground, but the actual threads are not. They are rolled. They are pitted. They do not have a good finish at all.


Time to break out the microscope!  Taking pictures of shiny things is not easy, but what the hell, I will give it a go.  

In this picture, you can see that the thread area of the screw has the same finish as the OD.  I don't see any pitting but I would say it is a pretty nice finish.  In the top left, you can see the rainbow shine that I typically associate with a ground finish.  





Another. You can see some chatter in the groove in the center of the thread profile.  Not perfect, but the ball never touches that portion so who cares?





Another.





Another.





Here is the rolled screw for comparison.  Not sure why I couldn't get a decent picture of the rolled screw.  It has more of a mirror surface on it which I think confuses the camera.





Here are the two of them side by side.  The picture isn't great, again the camera had trouble getting a good picture with the rolled screw in the shot.  







HeavyMetal747 said:


> He didn’t check the thread lead at all. That is the only thing that matters. Most ball screws are going to have some run out.


It is ok to address the poster if you disagree.  You'll notice that post with the ballscrew pictures and measurements was from the day the screws arrived.  It was based on initial impressions and the things I was able to measure.  It was not an in depth technical review, it was a quick post about new hardware I was (and still am) excited about.  



HeavyMetal747 said:


> A true ground C5 ball screw of any length cost $4000-$5000 dollars in the U.S.
> 
> This is because the lead of the screw is held to .0001” or less. The O.D. size just doesn’t matter. The run out, to a point, just doesn’t matter.


I am not sure where you are looking, but I have seen dozens for under $600.  Tormach mills for example use C5 ground screws and they have replacements available for $550.  I think you might also have your tolerances wrong, because a C5 screw tolerance doesn't come anywhere near .0001".  The permissible lead error/300mm is .0007" and the error/rotation can be .0003".  Even a C0 screw tolerance isn't .0001" or less on the lead.

I will also note that I didn't measure the OD of the screw.  I measured the OD of the machined journals to compare to the specifications I requested.  Those diameters absolutely do matter if I want a proper bearing and coupler fit.  



HeavyMetal747 said:


> I have spent hours upon hours upon days upon days looking and studying all of this, so I could have an intelligent conversation about it.
> 
> What you have seen is not a precision ground ball screw. It is a *******t way of telling you that it is.


I suppose everyone is welcome to their opinion, but that is quite a claim to make based on 2 or 3 pictures of an item and a few measurements.


----------



## HeavyMetal747

Ok, I will reply to you directly. The tolerance you talk about is for a C6 ball screw, not a C5.
 This not an opinion, it is fact.
I’m happy that you are happy with them.
I just don’t want this posting to mislead people on what they are really getting.
 I’ve been machining since 1981. If you can’t grind anything to .0001”, you don’t know how to use a grinder.
 Why is it that machine manufacturers can guarantee.0001”?
 It’s because they use ground ball screws that are ground to less than .0001”
 I’ve also been building machines for the last 10 years.
 This is the pic you posted. I blew it up




	

		
			
		

		
	
In

I’m sorry, it just doesn’t look that great to me.
Please go find the tolerance ratings.
They are not what you think
 I’m really not trying to be a jerk here. I’m just trying to explain how it really is.


----------



## shooter123456

HeavyMetal747 said:


> Ok, I will reply to you directly. The tolerance you talk about is for a C6 ball screw, not a C5.
> This not an opinion, it is fact.


I am not sure which tolerance you are referring to.  The classes specified by Hiwin and THK both have C5 permissible variation of 18 um (.0007") per 300mm and 8 um (.00034") variation per rotation.



HeavyMetal747 said:


> I’ve been machining since 1981. If you can’t grind anything to .0001”, you don’t know how to use a grinder.


Well I don't know how to use a grinder, nor how to make a ballscrew, but I know that parts simply aren't made to that level of precision for most applications.



HeavyMetal747 said:


> Why is it that machine manufacturers can guarantee.0001”?
> It’s because they use ground ball screws that are ground to less than .0001”
> I’ve also been building machines for the last 10 years.


My guess is that those machine manufacturers aren't using C5 screws and they are also using software error correction to make up for any of the deviation in the ballscrews. And I am not aware of many machine manufacturers that make those kinds of guarantees.  But I also don't see how that is relevant, because no one is making claims about these machines being able to hold tolerances of less than .0001".  Nor is that expected for a C5 screw. 



HeavyMetal747 said:


> I’m sorry, it just doesn’t look that great to me.
> Please go find the tolerance ratings.
> They are not what you think
> I’m really not trying to be a jerk here. I’m just trying to explain how it really is.


That would be the shipping oil in that picture.  The screw I took pictures of under the microscope is the same screw that was in the picture you posted. I noticed you didn't mention anything about the finish of the screw in an actual up close picture. 

I did look up the tolerance ratings.  They both say the same thing.  18 and 8 um.  I would be interested in seeing what you are looking at that says a C5 screw is supposed to be less than .0001" on the lead.


			https://tech.thk.com/en/products/pdf/en_a15_011.pdf
		




			https://www.hiwin.com/pdf/ballscrews.pdf


----------



## HeavyMetal747

Well, believe me or don’t. I am just offering a public service. As you said, you are guessing. I am not.


----------



## shooter123456

HeavyMetal747 said:


> Well, believe me or don’t. I am just offering a public service. As you said, you are guessing. I am not.


Ok, well the sources I posted said you are wrong.  Your only reference is your experience, which holds no weight when you posts things anonymously.  Anyone can pretend to be anyone online, but the things you say really don't reflect any amount of experience and you are unable to back up any of your claims.  That isn't a public service, that is just spreading an uninformed opinion.


----------



## HeavyMetal747

I figured I would be viewed poorly. I wasn’t trying to start an argument.
 I haven’t seen any data from you either.
Just some shiny pictures.
 As I said, if you are happy, that’s all that matters. It’s your machine. For what it’s worth the build looks nice.


----------



## rwm

Well at least I am learning about ball screw accuracy through this!
Robert


----------



## HeavyMetal747

I deal with Thomson linear more than any other company. They don’t use the same C scale for tolerances.
 They make two different rolled ball screws. One is .004” over 12”. The other is .001” over 12”
Then they get into the ground ball screws.
 I didn’t really mean to hijack the thread. 
 I understand what Hiwin and THK have listed as the C tolerances.
 I was asking you O.P. what the company you bought these from has listed.
 I just couldn’t find anything.


----------



## mattthemuppet2

I think that making strong inferences from a single picture, especially when that picture wasn't taken to show the specific thing you're talking about, is a little unwise. Refer to the high magnification pictures the OP posted and direct your comments at them. Do you see the things that you were concerned about originally?

It's ok to misinterpret a picture, happens all the time. I'm a trained microscopist and my postdoc PI was even more experienced than I was and we misinterpreted pictures (not at the same time, thankfully).


----------



## phazertwo

Similar to HeavyMetal747, I want to make damn sure the facts are out there, so that people looking to build hobby machines make informed decisions.  So here are some cold hard facts, supported with a few links so you can judge for yourself, and a little of my experience thrown in:

Hiwin and THK use a JIS (Japaneses Industrial Standard) standard for rating their ball screws. Thompson uses an ISO standard.  That is why THK/Hiwin/NSK and other Asian industry big boys will have a "C" grade, and Thompson has a "P" grade.  Generally, the largest difference between the two standards is in how the working load of a ball screw is calculated, though accuracy is graded differently as well, it's just not by a lot.  From what I can tell looking at the JIS standard and what Thompson is calling a P5, the JIS standard is a tighter tolerance.  For example Thompson says "P5" is 0.023mm/300mm.  So on a 900mm screw, you could have 0.069mm of positional error end to end.  Where as with a JIS C5 screw, you would be limited to 0.040mm.  Or in units we understand, the JIS screw is about 0.00114 of an inch better, over 36".  Or 0.001" over a yard.  That would actually be very difficult to measure with out a CMM... but I digress.

To be clear, Thompson does make some high quality stuff.  I'm not knocking them at all, they are just rating their stuff to a different standard.  Also remember that a screw has to meet or BEAT the published value in a standard, and quality manufactures are beating it.

From THK, showing C grade tolerances (SAME EXACT THING SHOOTER POSTED ABOVE):


			https://tech.thk.com/en/products/pdf/en_a15_011.pdf
		







And from Thompsons website:





						What are the standard accuracy grades?
					

Standard accuracy grades are defined by ISO 3408-3 which categorizes accuracy classes...



					www.thomsonlinear.com
				








Interesting tid bit I found trying to fact check myself...








						Ball screw standards: Differences between DIN, ISO, and JIS
					

Multiple ball screw standards govern everything from lead accuracy and load capacity definitions to ball nut tolerances and rigidity.




					www.linearmotiontips.com
				




If you want a ball screw that can hold 0.0001's of an inch positional tolerance, you are going to pay an insane amount for it.  Like absolutely insane.  And yes, holding 0.0001's for positional accuracy would be an incredible feat.  Grinding a diameter to 0.0001's, not really a huge feat today, my tool and die maker does it regularly for our fixturing (not to discredit the trade, I can't do it, like at all.  The only thing I can do on a surface grinder is burn through abrasive.  My tool and die maker is a regular bad ass, and there is a reason he builds this stuff, not me).  However, positional tolerance on a screw is EXTREMELY difficult to grind to that tight of a tolerance (not to mention it's an assembly, so you have tolerance stack issues),  so much so that if you want ±0.0001" positional tolerance for a 12" ball screw you are looking at a Grade C0 in the JIS standard (I have no access to the ISO, so I'm not sure what it comes out to, but probably a P0).  Want a ball screw over 12" to hold that tolerance?  Look somewhere besides the Japaneses because the JIS standard doesn't even go there, and I would put serious money on the ISO standard not going there either.  Considering how accurate our Mazak and Mori machines are... they are running some kind of ball screw mapping/compensation, almost certainly.

I also know that Okuma (at least they used to) and others offer linear scale feedback, which removes the need to have incredibly accurate ball screws, as the control uses the feedback to verify position constantly.  Many in the industry, including myself, consider this to be the most accurate way to control position on a machine.

*STEPS OFF SOAP BOX*

Shooter, your HOBBY machine is already kick ass, and it's going to be more kick ass with those ball screws.  That being said, if you want more accuracy out of it, I'd look at adding some linear scales and having them feed back to Linux cnc.  There are some people doing it on the youtube, and it looks like it's working pretty damn good!

Onward and upward with the build man, we're really enjoying it!

PZ


----------



## footpetaljones

Just to add another anecdote to the thread (because we don't have enough), I work as a service tech for an importer of high end Japanese machines (twin/triple/quad turret lathes, B axis mill-turns, etc.). The ballscrews we put in are C3 grade, usually from Koyo or THK. I don't usually pay attention to prices too much, but for a 32mm screw ~1000mm long our price is between $5000-$6000. Our machines don't have scales and we don't mess around with pitch error comp, just throw them in, reset backlash comp, and you're good. The biggest challenge to holding tenths is not the ballscrew, it's thermal growth, even on 10-15 year old machines worn to the bone. 

As with most things made in Japan, they set their own internal standards much better than the official standard.


----------



## shooter123456

On a slightly different subject, the BT30 spindle for this machine is happening.  The design has been modified a little bit since it was last mentioned, and it will now be a drop in spindle replacement with no modifications to the machine needed.  This means that if I mess something up terribly, I can switch it back to the R8 spindle and not have to worry about the machine being broken while (or if I suppose) make a new one.  

The spindle shaft is being made out of 12L14 and the main housing is being made out of 6061 aluminum.  The reasons for this are mostly for cost and ease of machining.  I know the spindle isn't going to be as strong or last as long being made out of 12L14, but this is mostly for a proof of concept and work out the kinks in the design.  If everything works the way I expect it to, the next iteration will be made out of a more appropriate material and hardened.  

For bearings, I am going with 2 7007C NSK universally matched bearings (7007CTRDUL P4Y) and it will have an additional 2 6906 deep groove ball bearings supporting the top of the shaft.  The lower AC bearings are rated for 13,000 RPM with grease.  I will be shooting for 10,000 RPM.  Since it will have drive dogs, I will also need spindle indexing at the very least for a tool changer.  I am thinking of adding some kind of low resolution encoder so that it can handle rigid tapping as well.  I will be using the same air cylinder I currently have to actuate the drawbar.  It can do about 2500 lbs so it will have more than enough force.  I will be using the same kind of top hat assembly to keep the drawbar pressure off of the bearings.  

I will be using a ball gripper and belleville stack so it will be ready for an ATC.  I am going to add a hardened bearing surface to keep the balls from damaging the inside of the spindle.  The bottom bearings will have a labyrinth seal to protect them.  I don't plan on adding seals to the top bearings, but the top of the spindle housing and head will be mostly sealed so I don't have many concerns about contamination at the top.  

For the pulley system, I am planning to use a taper lock assembly.  This way I don't need to worry about keyways or splines.  

The ODs of the main shaft have already been machined.  It has 3 threads, 2 for securing the bearings and one for the top hat.  I have drilled about halfway through already but stopped since I didn't have drills that could reach.  I will be getting a few longer drills soon to finish that.

Here is the main shaft.





Here it is with the NSK bearings.





Here is the main spindle housing being roughed in.





Here is my test for the gripper assembly.  The balls are 3/16".  





At this position, the gripper allows the pull stud to drop free.





And in this position, the pull stud is retained.





Last, this is the model as I am currently working with it.  If anyone has input that could help, that is always welcome!


----------



## mattthemuppet2

that's a seriously impressive project! I can't tell from the pics, but did you finish grind the bearing seats? Will you be balancing the spindle when you're done?


----------



## shooter123456

mattthemuppet2 said:


> that's a seriously impressive project! I can't tell from the pics, but did you finish grind the bearing seats? Will you be balancing the spindle when you're done?


Thank you!  The bearing seats on this one are not ground.  The next iteration will be hardened and ground though.

I will try to balance it, but I have not yet figured out how to do that.


----------



## shooter123456

Progress!

I got the turning finished for the housing.  That was pretty uneventful and all of the important fits are good.  I am already working on the design for the next iteration and that one will have the housing made out of steel and I am planning to do all of the turning in one set up.  That should make it easier to keep everything concentric.  

I made a D bit and a block for holding it in the tool post in order to drill the .875" hole 8" into the spindle.  The D bit cut well in aluminum so I am hopeful it will do well with the 12L14 steel.


----------



## phazertwo

Looking good man.  I think you are really onto something with the BT30 cartridge that fits in the existing head... Could even be a real market for it!

Just curious, what is the diameter of the spindle housing?  I'm pretty sure my 940 has a 75mm spindle housing... Maybe you see where I'm going here?

Keep up the good work!
PZ


----------



## shooter123456

phazertwo said:


> Looking good man.  I think you are really onto something with the BT30 cartridge that fits in the existing head... Could even be a real market for it!
> 
> Just curious, what is the diameter of the spindle housing?  I'm pretty sure my 940 has a 75mm spindle housing... Maybe you see where I'm going here?
> 
> Keep up the good work!
> PZ


There might be a market for it, but I have a hard time imagining it would be cost effective to make these.  It is a ton of work, so it would be very expensive to be worth the time to do it.

The portion that goes up into the head is 60mm on my machine.  For the next iteration, I am thinking that may go away.  There are a lot of compromises made in order to make that work and I am not sure how much performance will suffer as a result.


----------



## phazertwo

DANG!  That is small.

Nice work packing all of that into a small space!


----------



## kered

WoW, just read this impresive thread from start to finish, its comming along very nicely. I'm just starting my conversion, I have the ballscrews with double antibacklash ballnuts, Material for table and enclosure, material for the endfittings to mount the motors. My mill is a pm25mv rebadged as HBM Bf28, it has 1.1kw brushless motor with 2 speed pulley belt drive. Its my only mill so what I intend to do is dismantle 1 axis at a time, measure and draw out parts, rebuild and manually machine them, fit and move onto next axis and repeat, I was thinking of going with 2 shaft steppers so as not to lose manual mode but with a pendent fitted I think I can do the same thing as manual but using each motor to wind the handles.
For th OP shooter123456, the newer pm25mv have been modified, the X and Y endplates now have 70mm centres on the fixing bolts to table so dont rush out too many kits at the old measurment of 120mm between centres as you might get stuck with them for a while. If you would sell a copy of your drawings, especially the fastening nuts that fasten ballnut to table/sled, I would be interested as I'm not looking forward to modeling especially Z axis, disasemble check fit, reasemble and modify a couple of times to get it right, then repeating same on other axis. Let me know.
I've been thinking of using 5.5nm(778 oz/in) nema 24 al round or even next size down for X and Y, the nema 24's fit nema 23 mounting plates that I have so thats not a problem, Ill be watching the rest of the build in the front seat, thanks for sharing.


----------



## jimrk

kered said:


> WoW, just read this impresive thread from start to finish, its comming along very nicely. I'm just starting my conversion, I have the ballscrews with double antibacklash ballnuts, Material for table and enclosure, material for the endfittings to mount the motors. My mill is a pm25mv rebadged as HBM Bf28, it has 1.1kw brushless motor with 2 speed pulley belt drive. Its my only mill so what I intend to do is dismantle 1 axis at a time, measure and draw out parts, rebuild and manually machine them, fit and move onto next axis and repeat, I was thinking of going with 2 shaft steppers so as not to lose manual mode but with a pendent fitted I think I can do the same thing as manual but using each motor to wind the handles.
> For th OP shooter123456, the newer pm25mv have been modified, the X and Y endplates now have 70mm centres on the fixing bolts to table so dont rush out too many kits at the old measurment of 120mm between centres as you might get stuck with them for a while. If you would sell a copy of your drawings, especially the fastening nuts that fasten ballnut to table/sled, I would be interested as I'm not looking forward to modeling especially Z axis, disasemble check fit, reasemble and modify a couple of times to get it right, then repeating same on other axis. Let me know.
> I've been thinking of using 5.5nm(778 oz/in) nema 24 al round or even next size down for X and Y, the nema 24's fit nema 23 mounting plates that I have so thats not a problem, Ill be watching the rest of the build in the front seat, thanks for sharing.


If you have a 3D printer it can help with mock ups, slow but can work.


----------



## kered

As it happens I do have a 3d printer, not used it in a while, if its an .stl file they can now be loaded in fusion 360 AFIK, I do have some fusion files for the G0704 but they are slightly different. Anything rather than disarming everything especially Z as you upset trim aswell.


----------



## jimrk

kered said:


> As it happens I do have a 3d printer, not used it in a while, if its an .stl file they can now be loaded in fusion 360 AFIK, I do have some fusion files for the G0704 but they are slightly different. Anything rather than disarming everything especially Z as you upset trim aswell.


You might want to check this out on youtube.. his free plans are nice Fusion models


----------



## shooter123456

kered said:


> I was thinking of going with 2 shaft steppers so as not to lose manual mode but with a pendent fitted I think I can do the same thing as manual but using each motor to wind the handles.


I have heard a lot of people saying the same, but I wouldn't really bother.  It doesn't end up being too practical to turn handles through the motors.  You need to turn the motors off so that they aren't holding their position anymore, but that means the controller loses its position and you will need to re-touch off or rehome before using CNC again.  Even then, the steppers have detent positions so while you turn the handles, you feel clicks as it moves.  Simply jogging manually does the same thing, just through the controller. 



kered said:


> For th OP shooter123456, the newer pm25mv have been modified, the X and Y endplates now have 70mm centres on the fixing bolts to table so dont rush out too many kits at the old measurment of 120mm between centres as you might get stuck with them for a while.


That change must have been made before I got mine as mine is roughly 70mm (I measure in imperial, I am actually getting about 71.8mm spacing).  But thanks for looking out, that would have been rough if I made a bunch of parts that no one would ever need.  



kered said:


> If you would sell a copy of your drawings, especially the fastening nuts that fasten ballnut to table/sled, I would be interested as I'm not looking forward to modeling especially Z axis, disasemble check fit, reasemble and modify a couple of times to get it right, then repeating same on other axis. Let me know.


Shoot me a private message with your email address and I can send you some models. 



kered said:


> I've been thinking of using 5.5nm(778 oz/in) nema 24 al round or even next size down for X and Y, the nema 24's fit nema 23 mounting plates that I have so thats not a problem


Those motors might be a bit overkill, but nothing wrong with going bigger than needed.  I had great success with 400 oz in steppers for X and Y and their limitations were limited to speed which stronger motors wouldn't have helped.  Also, make sure you double check the dimensions for whichever motors you use.  I just had an issue in the past few weeks where I had to make some new parts for someone because they were using Nema 24 motors and the mounts didn't have the correct hole spacing.  Even though it is supposed to be standard, some manufacturers take liberties with the standards.


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## kered

Message sent, i think/hope, as to the motors i was a bit woried that the 3nm(424oz) might not be powerful enough for X&Y and definately not for Z but the 5.5nm gives me 778 oz which acording to david at arizona video is ample and even 650oz are fine, most nema 24 are hole compatible and to get them otherwise you have to ask, on the places I've looked they all say they are nema 23 hole pattern, also some of the nema 24's are 3 phase and AC, another posibility
Most of the 424 oz nema 23 I've seen have very high inductence well over the recomended max of 3.5 so heat will affect them, thats probably why your new drivers gave better performance as they use only the necesarry holding amps hence less heat

Jimrk, thanks for the video link, I have sean it but the files are dificult to load in fusion and try to get meassurments from, its probably just me as I'm lost a bit in fusion, I manage to make the odd model for 3d printing but managing other files no so much. I was hoping to be able to print them in pdf with measurments but not yet found how, even if possible. I also think its the older model by the endplates.
thanks
Derek


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## kered

I think I should start a new thread of the conversin rather than hijack this one any further.


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## jimrk

kered said:


> Message sent, i think/hope, as to the motors i was a bit woried that the 3nm(424oz) might not be powerful enough for X&Y and definately not for Z but the 5.5nm gives me 778 oz which acording to david at arizona video is ample and even 650oz are fine, most nema 24 are hole compatible and to get them otherwise you have to ask, on the places I've looked they all say they are nema 23 hole pattern, also some of the nema 24's are 3 phase and AC, another posibility
> Most of the 424 oz nema 23 I've seen have very high impedence well over the recomended max of 3.5 so heat will affect them, thats probably why your new drivers gave better performance as they use only the necesarry holding amps hence less heat
> 
> Jimrk, thanks for the video link, I have sean it but the files are dificult to load in fusion and try to get meassurments from, its probably just me as I'm lost a bit in fusion, I manage to make the odd model for 3d printing but managing other files no so much. I was hoping to be able to print them in pdf with measurments but not yet found how, even if possible. I also think its the older model by the endplates.
> thanks
> Derek


I'm no wizard in fusion but sketches are your friend.  if you turn them on you will find dimensions. also inspect-measure is good.











you can also export to other formats.. Good luck.

and file-new drawings you can create your own pdf with demensions


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## kered

As I mentioned I'm not so good with fusion, I'll give that a go and se what i can deduct from them.
I have measured my endplate bolt centres and they are 70mm, in francos drawings they are 120mm, the above images/drawings one is 70mm the other is 72, to be sure I think I will take mine of and draw round them then stick the drawing onto a piece of plate to get them exact, but just on this example there are differences, I would imagine the others too so which is correct, with the ballnut mounts its an industry standard size other than fisical size and the fixing holes to the table or Z sled and can be/are slightly slotted I hope. 
thanks again
Derek


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## kered

Just come across a problem, all the plans I have are for 1605 ballscrews and my Z axis is 2005 ballscrew, the problem is the block that fixes the ballnut to the head of the mill, it calls for a start block of 85.5x40x25mm, the 1605 ballnut is only 28mm but the 2005 ballnut is 36mm, when you put a hole of 36mm through a 40mm block you only have 2mm either side holding the full weight of the milling head, I doubt its enough, if you updated to a 2005 ballscrew what was the dimentions of the block you used or did you just bore it out and have it like mine, very thin. I might just make another one out of toolsteel just in case but a bigger block would be better A quick sketch with dimentions would be handy as if I make it too big it might get hung up somewhere.


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## shooter123456

kered said:


> Just come across a problem, all the plans I have are for 1605 ballscrews and my Z axis is 2005 ballscrew, the problem is the block that fixes the ballnut to the head of the mill, it calls for a start block of 85.5x40x25mm, the 1605 ballnut is only 28mm but the 2005 ballnut is 36mm, when you put a hole of 36mm through a 40mm block you only have 2mm either side holding the full weight of the milling head, I doubt its enough, if you updated to a 2005 ballscrew what was the dimentions of the block you used or did you just bore it out and have it like mine, very thin. I might just make another one out of toolsteel just in case but a bigger block would be better A quick sketch with dimentions would be handy as if I make it too big it might get hung up somewhere.


Flip the ballnut around.  Then you only need the hole through it to be enough to clear the screw.


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## kered

even flipping arround its only support is 2mm either side, although it does have 2 thin bolts in each half if it breaks. Having said that it also only bolts onto the head with a single cap screw. I think i'll try a one out of 46mm stock instead of 40mm, that will leave 5mm either side.


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## shooter123456

kered said:


> even flipping arround its only support is 2mm either side, although it does have 2 thin bolts in each half if it breaks. Having said that it also only bolts onto the head with a single cap screw. I think i'll try a one out of 46mm stock instead of 40mm, that will leave 5mm either side.


Are you thinking something that looks like this?


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## kered

yes, the bottom piece


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## kered

My ballnut is the opposit way and goes through the hole in the block, so the hole is 36mm, yours looks like it just sits on top so you only need a hole just over 20mm(the size of the ballscrew but you will lose travel, even more if you have double nuts like mine.


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## shooter123456

kered said:


> My ballnut is the opposit way and goes through the hole in the block, so the hole is 36mm, yours looks like it just sits on top so you only need a hole just over 20mm(the size of the ballscrew


You can take the ballnut off and put it back on the opposite way.


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## kered

I know but I have to make another one anyway as the hole is now 36mm, on the drawing it looks like your fixture block has a hole a little more than 20mm maybe 1" at most so only the threaded ballscrew can pass through but the ballnut cannot, you can tell by the distance from the boltholes to the centre.


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## shooter123456

kered said:


> I know but I have to make another one anyway as the hole is now 36mm, on the drawing it looks like your fixture block has a hole a little more than 20mm maybe 1" at most so only the threaded ballscrew can pass through but the ballnut cannot, you can tell by the distance from the boltholes to the centre.


I feel like there may be a bit of communication error here as you are repeating back to me exactly what I am saying.  

I noticed you added a bit more to a previous post, but even with a double nut screw, no travel is lost having the ballnut facing down.


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## rwm

That's an awesome pic. Fusion?
Robert


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## kered

The way mine is made to mount is different and is similar to this





The nut goes through the block and is not sitting on it like yours, The photo is not mine Its a download from google(thanks original owner)to illustrate what I mean by the nut going through the block. If I turn it round like yours, mine being double I will loose lift as its about 4-5" long, If I put it on the underside I will have to be carefull not to lower too much or balls might fall out.
Best way is make a new one but didn't want to disassemble to measure and reasemble to make if someone already had made one to fit a 2005 ballnut thats 36mm diameter instead of 28 like the 1605 ballnut.


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## phazertwo

Shooter, not sure you notifications are working.  Check your messages.

PZ


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