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PM932 CNC Build

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TomS

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Jay - Here's the pictures.

Tom S.

Backside view of the pump and recirc plumbing. The valve in the picture is the recirc/bypass valve. Yes, that's a 1" tube dumping back into the reservoir. This pump puts out something like 650 gal/hr. at 50 psi.
20161101_093018_resized.jpg

Don't look too close at the pump mounting bracket. I set this up quickly to see how well it worked and haven't got back to making a proper mount.
20161101_093027_resized.jpg

A view of the pump discharge piping. Suction line at the bottom and the feed line to the mill coming out of the left side of the tee.
20161101_093045_resized.jpg

I routed the feed line through a hole in the mill stand and up through the column then drilled a hole in the sheet metal panel on the back of the column and ran the feed line to the distribution manifold. You can see the right side nozzle below. You can also see the tee fitting behind the vertical way cover that feeds my wash down garden hose nozzle.
20161101_094558_resized.jpg
 

jbolt

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Looking at the pump manual it says it is not self priming. Are you using the supplied check valve? Any issues with startup?

Aslo are you switching the pump on/off in Mach3 or just running it constant and using a solenoid to turn the spray nozzles on/off?

I'm using a solid-state relay to switch my current pond pump on/off w/Mach3. It "should" handle this pump......
 

TomS

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Looking at the pump manual it says it is not self priming. Are you using the supplied check valve? Any issues with startup?

Aslo are you switching the pump on/off in Mach3 or just running it constant and using a solenoid to turn the spray nozzles on/off?

I'm using a solid-state relay to switch my current pond pump on/off w/Mach3. It "should" handle this pump......
Yes, I'm using the supplied check valve. Had to prime the pump once on initial startup. Haven't had to do it since.

I have an on/off switch mounted on my enclosure next to the door. When I start a run I flip the switch and when done flip it to the off position.

I turn the coolant nozzle valves off when doing a wash down. Besides not having to deal with coolant spraying out of the nozzles it also keeps the coolant from draining back to the reservoir thus keeping the pump primed.

Tom S.
 

jbolt

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More updates to the machine. With the new enclosure I mounted the computer and monitor to the enclosure frame. The new computer is a Dell Inspiron Micro desktop running windows 10. With only a 32gb HD drive they are not much good except for web surfing and email but it's perfect for a small dedicated windows based machine controller. I found this on fleabay refurbished for about $100. when not in use the keyboard folds up and the whole assembly fold in. The monitor mounting plate and keyboard tray are aluminum sheet and were cutout on the CNC router.

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jbolt

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Next is the revamp of the coolant system. I went with the pump TomS is using. I found a couple threads on another forum where they had installed a whole house filter in the feed line to filter out small particles. With the higher volume pump I thought this might be a good idea. We will see. I'm also going from two spray nozzles to four. Sometimes two does not cover the tool path. I'm still waiting for the additional nozzles before I can test. I'm also going to try a new coolant, KOOL Rite 2290. All the home shop users I have found using it have very favorable reviews. Fingers crossed. I also relocated the mist system to the side for better access to the spindle.

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jbolt

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After swapping out the original stepper drive and power supply I finally got the 4th axis up and running.

Nothing special to look at. I was going to make a cover for the motor and coupler but I think I will just use a plastic bag. I may swap the stepper for a shorter body stepper and shorten the shaft to make it more compact. As it is now the motor sticks out too much to close the enclosure doors to use flood coolant.

Rotary Table 01.png
 

TomS

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What brand and type of angular contact bearings did you use in your spindle? I've started searching for bearings for my spindle but the suffix codes are confusing. I'm trying to find an abec 3 bearing (abec 5 and 7 pricing is through the roof) that will operate at 10000 rpm or higher. Then there are the contact angles, e.g. 15, 20, 29, 40 degrees. Which contact angle did you go with? Anything else I should consider?

Thanks,

Tom S.
 

jbolt

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I'll see if I can find the order. What size are the bearings? I replaced the bearings on the spindle on my other mill around the same time.
 

jbolt

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I think it is this bearing. You should verify the size. Same bearing from Amazon.

ABEC-5, 15 deg (15-18 are recommended for mills), resin cage. The data from Nachi says the max RPM for grease is 18,000.
 

TomS

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I think it is this bearing. You should verify the size. Same bearing from Amazon.

ABEC-5, 15 deg (15-18 are recommended for mills), resin cage. The data from Nachi says the max RPM for grease is 18,000.
Your information was very helpful. It helped me understand the suffix codes so that I could focus in on the correct bearings for the application. Found the bearings I need on eBay at a fraction of the cost (less than $100 for both). One is an ABEC 5 and the other is an ABEC 7. Two different brands but both are well known (SKF and NSK). The mechanical part of the conversion is coming together.

From what I understand VFD's put out a lot of electrical noise. How much separation is recommended between the VFD and the electronics (BoB, motor drivers, etc.)? If I remember yours is mounted on the wall behind your machine. Is this for convenience or is noise your concern?

Tom S.
 

jbolt

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My VFD is mounted to the side of the control box. This was the easiest place to mount at the time.

There are no sensitive components in the control box.

The router we built for the school has all the electronics in the same enclosure. On recommendation from an Industry expert in electrical noise we created compartments within the enclosure separating high voltage, low voltage and signal wiring. Except for the VFD to spindle wire all other shielded wires, the sheilding is terminated at the enclosure. Shielding within the enclosure acts like an antenna.

The enclosure that houses the BoB, motion controller & drives on my mill has mixed high low volt and signal with all sheilding terminating at the enclosre. Noise has never been an issue.

I suspect an open loop stepper system is less susceptible to noise than a servo/encoder system.

Sent from my SAMSUNG-SM-G900A using Tapatalk
 

TomS

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My VFD is mounted to the side of the control box. This was the easiest place to mount at the time.

There are no sensitive components in the control box.

The router we built for the school has all the electronics in the same enclosure. On recommendation from an Industry expert in electrical noise we created compartments within the enclosure separating high voltage, low voltage and signal wiring. Except for the VFD to spindle wire all other shielded wires, the sheilding is terminated at the enclosure. Shielding within the enclosure acts like an antenna.

The enclosure that houses the BoB, motion controller & drives on my mill has mixed high low volt and signal with all sheilding terminating at the enclosre. Noise has never been an issue.

I suspect an open loop stepper system is less susceptible to noise than a servo/encoder system.

Sent from my SAMSUNG-SM-G900A using Tapatalk
Got it. Thanks.

Tom S.
 

jbolt

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Update on the coolant system. My diy check valve lasted until the spinning action created by the coolant flow cut the thin wall arrrow shaft serving as a guide rod in half. I replaced it with a solid rod and it worked for a few days and then would not pump even though it had a prime. I tried another check valve at the same. I removed the pump and flushed it out and reassembled with the commercial check valve. It ran for one tool op and quit at the tool change. I like the pump when it runs but too much time wasted fiddling around with it.

I picked up a 1/2 hp sump pump from HF. They are changing brands so this one is branded Drumond. There previous 3/4 hp pump which a lot of diy CNCers use was rated at around 2800 GPH. They didn't have any pumps in 3/4 hp so I just opted for the 1/2 hp. I didn't bother to read the label. It is rated at 4400 GPH. Holy crap this thing moves fluid. with the bi-pas valve at 70% open it will overwhelm the drain 1-1/2" drain outlet so it is about 85% open. No check valve needed and it has almost no startup delay. Much much better now. The 1/3 hp model of this pump would have been more that sufficient.

I had to laugh at the labels on the pump.

That's a short waranty...

20170105_185724.png

Indoor use only? I guess they don't want it to get wet...LOL

cp02.png

I also up sized the coolant tank from 7 gallons to 12 gallons. No chance of sucking air now.

cp04.png cp03.png
 

TomS

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Update on the coolant system. My diy check valve lasted until the spinning action created by the coolant flow cut the thin wall arrrow shaft serving as a guide rod in half. I replaced it with a solid rod and it worked for a few days and then would not pump even though it had a prime. I tried another check valve at the same. I removed the pump and flushed it out and reassembled with the commercial check valve. It ran for one tool op and quit at the tool change. I like the pump when it runs but too much time wasted fiddling around with it.

I picked up a 1/2 hp sump pump from HF. They are changing brands so this one is branded Drumond. There previous 3/4 hp pump which a lot of diy CNCers use was rated at around 2800 GPH. They didn't have any pumps in 3/4 hp so I just opted for the 1/2 hp. I didn't bother to read the label. It is rated at 4400 GPH. Holy crap this thing moves fluid. with the bi-pas valve at 70% open it will overwhelm the drain 1-1/2" drain outlet so it is about 85% open. No check valve needed and it has almost no startup delay. Much much better now. The 1/3 hp model of this pump would have been more that sufficient.

I had to laugh at the labels on the pump.

That's a short waranty...

View attachment 143254

Indoor use only? I guess they don't want it to get wet...LOL

View attachment 143255

I also up sized the coolant tank from 7 gallons to 12 gallons. No chance of sucking air now.

View attachment 143257 View attachment 143256
Sorry to hear the original pump didn't work out. Sounds like you found a solution to your problem though.

Reading the labels it's clear that the pump warranty is valid only if you don't use it. LOL

Tom S.
 

jbolt

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Sorry to hear the original pump didn't work out. Sounds like you found a solution to your problem though.

Reading the labels it's clear that the pump warranty is valid only if you don't use it. LOL

Tom S.
No worries Tom. I like the pump but it does not like me. The new one is a lot noisier. Makes the machine sound bigger than it is. LOL We will see how it holds up.
 

TomS

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Made some good progress on the belt drive conversion this week. The spindle bearings have been changed to angular contact bearings. The bearings are a press fit so I had to heat / cool components to get the bearings to drop in. That all went well except I forgot to preload the bearings when I put the spindle in the quill body. After the parts had cooled and or warmed up the locknut on the spindle would not move the bearing. I ended up using a piece of pipe, with the ends turned true, over the splined end and made a shim the thickness of the up-down play in the bearings and used those to press the bearing into the proper position. Keeping my fingers crossed I got enough preload on the bearings .

The pulleys are for poly-J belts. This has been used in a lot of other belt drive conversions so I went with it. The only downside is the vee-grooves are 40 deg. Carbide inserts for these are very expensive and seem to only come in 5 or 10 packs so the solution is to grind a cutter from HSS. I went with the typical 1:2, 2:1 pulley ratios. One thing to note is the splined sleeve has a pocket for a 6mm shaft key. I have a set of standard keyway broaches so I cut a 3/16" keyway in the pulley and made a 6mm to 3/16" adapter key out of 1/4" keyway stock.

The spindle, head cap with spline drive, pulleys and motor are installed and I was able to manually run the motor for the first time tonight. Everything ran great up to full speed (about 7K rpm at 120hz). My biggest issue is the noise and some vibration from the splined sleeve/shaft area. I'm not sure if others have run into this same issue. It is a lot noisier than I expected but not nearly as noisy as the gear head. I will try and post a video of the noise problem later in the week.

View attachment 98615 View attachment 98614 View attachment 98613 View attachment 98612
Jay - I've got my AC bearings and the Kluber spindle grease will be here sometime this week. Been surfing the net reading up on bearing preload but there doesn't seem to be much agreement on how to do it. Some say tighten the upper bearing lock nut until end play is removed then snug it a bit more to set preload. Others say leave a small amount of end play because the spindle will grow with heat and take up the end play and then some. And there are those that refer you to the manufacturer's technical literature. I'd need a PHD in mathematics to understand the formula's let alone calculate them. I'm a hobbyist and like most of us don't have the tools nor a climate controlled shop to accurately measure within a couple of tenths.

I like your approach to preloading spindle bearings. If I understand what you did you seated both bearings against their respective shoulders using a piece of pipe and shim. Where did you put the shim? Under the upper bearing outer race? Why a shim when you can use the lock nut to set preload? Did I leave something out?

Tom S.
 

jbolt

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Jay - I've got my AC bearings and the Kluber spindle grease will be here sometime this week. Been surfing the net reading up on bearing preload but there doesn't seem to be much agreement on how to do it. Some say tighten the upper bearing lock nut until end play is removed then snug it a bit more to set preload. Others say leave a small amount of end play because the spindle will grow with heat and take up the end play and then some. And there are those that refer you to the manufacturer's technical literature. I'd need a PHD in mathematics to understand the formula's let alone calculate them. I'm a hobbyist and like most of us don't have the tools nor a climate controlled shop to accurately measure within a couple of tenths.

I like your approach to preloading spindle bearings. If I understand what you did you seated both bearings against their respective shoulders using a piece of pipe and shim. Where did you put the shim? Under the upper bearing outer race? Why a shim when you can use the lock nut to set preload? Did I leave something out?

Tom S.

Hi Tom,

What happened was that when I inserted the spindle while everything was free fitting I did not tighten the lock nut to fully seat the inner race at the upper end of the spindle. When the temps normalized the inner race was tight to the spindle and would not budge with the nut. This left some up-down play in the bearings. I'm trying to remember what it looked like but the pipe and shim set the max amount I could press in the inner race to seat the bearing and a few thou for preload. I had some concerns about getting it too tight. So far so good.

Had I done things correctly to begin with I would have tightened the nut until the bearings were starting to get stiff and then backed off a little. Not very scientific.

The lock nuts are a bit problematic in that they are retained by a star lock washer where you have to bend one of the star arms into a slot on the nut. If I recall I used some thin shims under the nut to get the lock nut to align with the lock washer.

My spindle temps only get a few degrees above ambient, never much warmer than that. Mine are both C5 so if you have C7 they may be more susceptible to heat expansion but I'm not sure what that would be.
 

TomS

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Hi Tom,

What happened was that when I inserted the spindle while everything was free fitting I did not tighten the lock nut to fully seat the inner race at the upper end of the spindle. When the temps normalized the inner race was tight to the spindle and would not budge with the nut. This left some up-down play in the bearings. I'm trying to remember what it looked like but the pipe and shim set the max amount I could press in the inner race to seat the bearing and a few thou for preload. I had some concerns about getting it too tight. So far so good.

Had I done things correctly to begin with I would have tightened the nut until the bearings were starting to get stiff and then backed off a little. Not very scientific.

The lock nuts are a bit problematic in that they are retained by a star lock washer where you have to bend one of the star arms into a slot on the nut. If I recall I used some thin shims under the nut to get the lock nut to align with the lock washer.

My spindle temps only get a few degrees above ambient, never much warmer than that. Mine are both C5 so if you have C7 they may be more susceptible to heat expansion but I'm not sure what that would be.
Now I understand. I polished the spindle upper bearing journal so the bearing just slides on. That should help with assembly. I like your idea of using shims under the lock nut to get the proper preload and have the slot align with the lock washer tab. I'm going to steal your idea.

Tom S.
 

MontanaAardvark

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After swapping out the original stepper drive and power supply I finally got the 4th axis up and running.

Nothing special to look at. I was going to make a cover for the motor and coupler but I think I will just use a plastic bag. I may swap the stepper for a shorter body stepper and shorten the shaft to make it more compact. As it is now the motor sticks out too much to close the enclosure doors to use flood coolant.

View attachment 139002
Is that the 6" table from Wholesale Tools? I just got one in December.

Putting the motor mount on it and getting it running is fairly close to the top of my To Do list. I have motor mounts I made for the Hoss Phase 1 conversion and was hoping one of them would be useful.

I haven't even looked for a way to take it apart, yet, so no idea of dimensions or anything.


Bob
 

jbolt

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Is that the 6" table from Wholesale Tools? I just got one in December.

Putting the motor mount on it and getting it running is fairly close to the top of my To Do list. I have motor mounts I made for the Hoss Phase 1 conversion and was hoping one of them would be useful.

I haven't even looked for a way to take it apart, yet, so no idea of dimensions or anything.


Bob
It is a Phase II rotary table I got from Enco. Mounting a stepper to it was straight forward.

The tricky part was finding a 4th axis Mach3 post processor for HSM Works. Most Mach3 3-axis post processors are 4th axis ready but it is disabled in the code.
 

SheffS4

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Hello Jay,

Thanks again for the design files, I'm the guy who's planning to do the DMM-Tech conversion.

Do you have any return coolant drains on the table itself? If not, how do you deal with the t-slots filling with coolant?
 

jbolt

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The table has one drain outlet on the right rear. I run high volume coolant so it overwhelms the drain anyway. That does not matter with the enclosure.

Sent from my SAMSUNG-SM-G900A using Tapatalk
 

SheffS4

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Got it, thanks. I'm running some temporary flood for some manual steel cutting for now with strategically placed catches and flexible hose.

Are you using set screw style couplers for your steppers? DMM-Tech recommended keyed couplers but i'm struggling to find a good option. The set screw style is by far the most common it seems.

That chip pan is so nice, I think I'm gonna have to go to a local sheet metal fab shop for a quote to make one. What gauge sheet metal did you use?
.
 

jbolt

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Got it, thanks. I'm running some temporary flood for some manual steel cutting for now with strategically placed catches and flexible hose.

Are you using set screw style couplers for your steppers? DMM-Tech recommended keyed couplers but i'm struggling to find a good option. The set screw style is by far the most common it seems.

That chip pan is so nice, I think I'm gonna have to go to a local sheet metal fab shop for a quote to make one. What gauge sheet metal did you use?
.
To maximize the use of flood coolant you need volume and pressure to evacuate the chips from the cutter. My first coolant system was a small pond pump and a 5 gal bucket. worked okay but with the high volume system my finishes are much better. I highly recommend Koolrite 2290 coolant. This is by far the most home shop user friendly and machine friendly coolant I have used so far.

I'm using set screws on the couplers. What I do for round shaft motors is replace the set screws with pointed set screws and drill a mating detent in the shaft. Never had an issue done that way. I also add a second set screw the each end of the coupler at 90 deg from the other. If you motor shafts have flats use cup point set screws on the flat, no detent needed. If my stepper shafts had key-ways I would broach a key-way into a coupler.

The chip pan is .060 aluminum. I have a buddy who does outside sales for a shop that has a laser cutter and large press brake. He cut and bent the pan pieces for me for the cost of materials.
 

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Yeah I gave up on the flood coolant for now and am sticking with my koolmist setup until I can get a proper chip pan.

Thanks for the tip on coolant type, I got some microsol 685 that I purchased a little while ago for now. Should last a while considering I'm not using it right now lol

I will need to get / make a broaching tool for the pulleys / couplers.

How is your Fabco air cylinder working out? Looks like it'll do 3349 lbs with 90psi. Working well for your TTS with no pullout? I saw you mention you were considering an electric drawbar, like the one that Novakon sells. Seems pretty straightforward except I'm not sure how they handle the torque setting. Are you still considering this option?
 

jbolt

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Yeah I gave up on the flood coolant for now and am sticking with my koolmist setup until I can get a proper chip pan.

Thanks for the tip on coolant type, I got some microsol 685 that I purchased a little while ago for now. Should last a while considering I'm not using it right now lol

I will need to get / make a broaching tool for the pulleys / couplers.

How is your Fabco air cylinder working out? Looks like it'll do 3349 lbs with 90psi. Working well for your TTS with no pullout? I saw you mention you were considering an electric drawbar, like the one that Novakon sells. Seems pretty straightforward except I'm not sure how they handle the torque setting. Are you still considering this option?
I like the pneumatic drawbar on this mill since I have air for mist and a air nozzle for clearing chips and coolant. I have a DIY electric on my HD drill press since it has no air near it and I don't plan on bringing it there. The 3-stack air cylinder woks okay but it is just barely enough for most things. I can get pullout with larger end mills and aggressive feeds. I plan to replace it with a 4 stack cylinder ay some point.
 

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Thanks Jay.

I compared some numbers (cost/force) of the Fabco cylinders and the 4" bore 4 stack will give you the best bang for your buck in that price and force range. I will be going the same route.

Going with RM2505 ballscrew on Z, would you still feel the need to support the bottom of the ballscrew with a thrust bearing? I ran some ballscrew critical speed and column strength calculators and it doesn't seem necessary.

Also is there a reason you chose to use a thrust bearing instead of a BF / FF support? Was greater axial load handling without any radial loading your goal?
 

jbolt

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Thanks Jay.

I compared some numbers (cost/force) of the Fabco cylinders and the 4" bore 4 stack will give you the best bang for your buck in that price and force range. I will be going the same route.

Going with RM2505 ballscrew on Z, would you still feel the need to support the bottom of the ballscrew with a thrust bearing? I ran some ballscrew critical speed and column strength calculators and it doesn't seem necessary.

Also is there a reason you chose to use a thrust bearing instead of a BF / FF support? Was greater axial load handling without any radial loading your goal?
I chose to support the Z ball screw because I was uncomfortable hanging the weight of the head off the end of the ball screw shaft with a cheap 1/4" wide nut that is retained by a crappy set screw. The thrust bearing supports the shaft and takes most of the hanging load. I'm not an engineer and my concern may be unfounded but I have built (and broken) enough stuff over the years (some designed by engineers) to be cautious. There are other builds out there that do not have an end support or constraints that are working fine so far. Seems like cheap insurance to me but YMMV.

How is the build going?
 

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Fair point, I wouldn't trust a set screw that much either. I got a brake on my Z axis servo for safety so I should probably support the bottom of the leadscrew. I'll consider my options.

I'm still in the gathering parts and over-researching everything as I always do stage. All I have so far is DMM-Tech servos, drivers, and a Meanwell RSP-1600-48 from work. Just about to finalize the ballscrew order with Chai after laughing hysterically at a quote from Nook. It looks like all the measurements on your machine are the same as mine so far, which is a PM932-V-PDF so I may just order the same length screws as you spec'd.

I have a MB2 BoB (looks really nice, I look forward to using it), Ethernet Smoothstepper, and china special tool setting probe (SK-66B) on the way. Need to look into my delta VFD that came with the machine and see what options I have to control it. Went with ModBus last time. Works great but was a bit of a headscratcher trying to set it up.

This will be my 3rd CNC electronics build, first mechanical conversion though. I should probably start a thread and stop taking over yours! My workshop is very small and not very nice to photograph though lol. I'm still not sure how I'm going to do the machining on the saddle as this is my only mill, will probably need to call on some help.
 
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