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Taking the CNC Plunge

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techbuilder

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If you haven't already done so you might take a look at the CNC builds by jumps4 and jbolt. My conversion is based on their builds.

Tom S.
No actually I haven't, thank you Tom and I really appreciate the time you have taken to answer my questions and provide screen shots as well.

I've included the links down below to anyone else who is curious on their threads who stumbles upon your thread on

Jbolt
http://www.hobby-machinist.com/threads/pm932-cnc-build.21442/

Jumps4
http://www.hobby-machinist.com/threads/rung-fu-clone-rf-45-zx45-cnc-conversion.8187/
 

TomS

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No actually I haven't, thank you Tom and I really appreciate the time you have taken to answer my questions and provide screen shots as well.

I've included the links down below to anyone else who is curious on their threads who stumbles upon your thread on

Jbolt
http://www.hobby-machinist.com/threads/pm932-cnc-build.21442/

Jumps4
http://www.hobby-machinist.com/threads/rung-fu-clone-rf-45-zx45-cnc-conversion.8187/
Thanks for posting the links. As you work through your build please post pictures. Everyone on this site will be interested in what you are doing. And of course if you have questions do not hesitate to ask.

Tom S.
 

techbuilder

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Thanks for posting the links. As you work through your build please post pictures. Everyone on this site will be interested in what you are doing. And of course if you have questions do not hesitate to ask.

Tom S.
Ohh I definitely will!
 

techbuilder

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Hey Tom,

Another quick question before I start on my build.
The drawings you used from Jumps4, did you have to make any changes to use on your mill or was it pretty much spot on?
 

TomS

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Hey Tom,

Another quick question before I start on my build.
The drawings you used from Jumps4, did you have to make any changes to use on your mill or was it pretty much spot on?
The drawings from jumps4 were not used verbatim, just for ideas when I built mine. I double checked the X and Y motor mount bolt pattern to my mill. I found, through trial and error, that the holes on the ends of the table and on the front of the base were drilled and tapped randomly. My Z motor mount is significantly different than jumps4 so his drawings weren't applicable. Hope this helps.

Tom S.
 

jbolt

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jumps4 has a mill from a different manufacturer so it will be different. The mounting holes for the factory acme screw bearing blocks are hand fitted so the bolt patterns are not exactly the same from machine to machine.
 

TomS

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This is the Chinese version of hand fitting. LOL

Table End Drilling 01.jpg

BTW - Jumps4 used a Wholesale Tool Milling machine. As jbolt said the acme screw bearing blocks are hand fitted at the factory. It's just that sometimes the hand fitting isn't what we would like it to be.

Tom S.
 

techbuilder

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Ohh jeez haha

I just ordered the 1600oz stepper motors and the 60w power supply for them, Still waiting on a little more cash for the 4200oz and a power supply for it.

My temporary goal is to machine up some motor mounts for the x and the y and use the stock acme threads to machine some parts (the z axis motor mount) while manually operating the Z, did this at the old machine shop I worked at with an old time NC machine.

We shall see if the motors have enough oompf to turn the axis with an acme lead screw.
 

TomS

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Ohh jeez haha

I just ordered the 1600oz stepper motors and the 60w power supply for them, Still waiting on a little more cash for the 4200oz and a power supply for it.

My temporary goal is to machine up some motor mounts for the x and the y and use the stock acme threads to machine some parts (the z axis motor mount) while manually operating the Z, did this at the old machine shop I worked at with an old time NC machine.

We shall see if the motors have enough oompf to turn the axis with an acme lead screw.
What brand motors and power supplies did you get? Did you buy a kit? Your approach is logical and should work. Good luck!

BTW - I'm gathering materials for a belt drive conversion. I'll post pictures here so others can see what I'm doing.

Tom S.
 

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TomS

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I bought some hong kong billy bobs from eBay individually

I bought these steppers
http://www.ebay.com/itm/321594224727?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

and these power supplies
http://www.ebay.com/itm/231617048103?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT

Oooo nice! I look forward to seeing it.
Same motors and drivers I have. They've worked flawlessly for me.

A suggestion and please don't take this the wrong way. You should start your own thread so you can track your build in one place and others can see your progress from the beginning up to it's conclusion. I and others are more than willing to help but it may get confusing if we respond to your build in my thread. And you won't get the exposure you need when asking for input. Again, I'm trying to be helpful.

Tom S.
 

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I asked a few questions in another thread about adding a 3 phase motor and VFD to my PM-932 mill. Thanks to jbolt and mksj who were very helpful in answering my questions and providing valuable information. My plan is to do all of the mechanical work first then tackle the electrical and electronics last. I'm going with a Hitachi WJ VFD. The pulley ratio will be 2.5:1 which gets me to 9000 spindle rpm at 120 Hz. I will be replacing the spindle bearings with AC bearings. If 9000 poses a problem I can always reduce the large pulley diameter later. So off I went and started gathering materials.

More pictures and loads of questions to follow.

Tom S.


This is the motor mksj pointed out to me on eBay. It's a new in the box Marathon Black Max 2HP 3 phase inverter duty. Was able to snag it for $104 plus shipping.
20161123_125306_resized.jpg

Here's the material for the pulleys and one motor support rail. The second motor support rail was in the mill when I snapped these pictures. The piece in the lower left is my tool changer mount. Still have some work left to do on it.
20161123_125435_resized.jpg

It's not a good picture but this is the second motor support rail being machined.
20161123_125448_resized.jpg
 

TomS

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Made some progress on my belt drive conversion. Finished the motor adapter plate, the tool changer mount, and the side rails. Today I started machining on the motor and spindle pulley's.

Tom S.

20161202_123111_resized.jpg
 

TomS

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Made some more progress today. I finished up the spline drive shaft modifications but not without a bit of trouble. Somewhere I read that most of the asian mill drills don't have hardened gears. Well I have one of the few mills that don't fall into that category. The gear on my shaft must have been in the Rc55+ range. With the hardness and interrupted cut I went through a few carbide inserts. I tried I22, C5 and C1 grades. C1 worked the best but still didn't last more than three passes. Once I got below the tooth root it machined fine. Anyway I got er done.

Tom S.

I opted to go with a snap ring to retain the spindle pulley rather than a nut. I'm going to bore the pulley for a .001" interference fit and with the drive key it's not going anywhere. I'll trim the top to length after the pulley is done.
20161205_154006_resized.jpg

The grooves next to the right hand snap ring and the one left of it are what's left of the undercuts on each side of the gear and hub. Next up is to order the bearings. These are going to be a little pricey (about $50 each) because I need bearings with non-contact seals. I can find bearings with contact seals for less than $10 each. My goal is to get to 9000 rpm but bearings with contact seals are limited to 7000 rpm. Non-contact seals are rated to 12000 rpm. Bearings are good to 15000. Seals are the limiting factor.
20161205_153916_resized.jpg
 

jbolt

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My gear was hard but I got through it with no trouble. I have one of these insert holders for doing interrupted cuts. It uses the odd corners of 80deg inserts so I keep my worn out or chipped inserts for jobs like that.
 

TomS

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My gear was hard but I got through it with no trouble. I have one of these insert holders for doing interrupted cuts. It uses the odd corners of 80deg inserts so I keep my worn out or chipped inserts for jobs like that.
Wish I had one of those yesterday. My tool holders take TNMG inserts. Usually they work fine on any material I throw at them.

Tom S.
 

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More work completed on the belt drive conversion today. Got the bearings for the spindle splined sleeve. The guy at the local bearing house recommended I go with double shielded bearings instead of the non-contact sealed bearings. If they sling the grease out at high rpm I'm not going to be happy. We'll see.

Tom S.

Finished the motor and spindle pulleys.
20161207_155407_resized.jpg

Mocked up the parts on the mill to make sure everything fit before drilling and tapping the bolt holes for the motor plate and tool changer riser. Sure enough the sides of the gear head top cover aren't square to the top. Not a big deal just had to compensate for it when I laid out the holes.
20161207_143233_resized.jpg

20161207_143339_resized.jpg
 

TomS

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Yesterday I removed the spindle cartridge and disassembled the spindle. Bearing cups looked OK with just slight discoloration on the rolling surfaces. No scratches or grooves which was better than I expected. But what I did find was metal chips packed inside the lower spindle bearing end cap. This was because my mill didn't come with a lower spindle seal (part 75) as shown in the parts diagram. Anyone else missing the seal? For those that haven't checked it's very easy to unthread the end cap. There's three small dimples in the end cap face where you can get the end of a punch into to exert a small amount of rotational force to unscrew it. I recommend that you check it out. It may save you having to change out the bearing.

Here's a screen shot of the PM-932 manual showing the spindle end cap (part 74) and spindle seal (part 75). Mine didn't have part 75.
Screen Shot 12-13-16 at 09.48 AM.PNG

And here's a picture of the interior side of the end cap. The counterbore is an odd ball dimension something like 62.1mm. I'm going to make an insert to reduce the bore to a standard dimension like 55mm or there abouts then buy an off the shelf seal to fit the spindle OD. For info my spindle OD is 1.650" (41.9mm) but because I'm going to spin this thing up to 9000 rpm a contact seal won't live at that speed. I can get a seal for a 1.655" shaft which gives me a small amount of clearance which keeps from frying the seal and will keep out most of the chips and coolant.
20161213_092736_resized.jpg

Tom S.
 

jbolt

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Mine didn't have a seal either. I put a thick o-ring on the spindle behind the cap to cover the gap.
 

TomS

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Mine didn't have a seal either. I put a thick o-ring on the spindle behind the cap to cover the gap.
Interesting that the manual shows a seal but they ship the mill without one. I like your o-ring fix.

Tom S.
 

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Update on my PM-932 belt drive conversion. Got my angular contact bearings and the Kluber bearing grease is on the way. Thanks jbolt for helping me sort out AC bearing suffix codes. Ordered my VFD (Hitachi WJ200-015SF). Should be here early next week. Then the fun begins.

Tom S.
 

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My VFD (Hitachi WJ200-015SF) arrived this past Saturday. The first order of business was to mount it in the enclosure. Got that done today and will mount the enclosure on the control cabinet tomorrow after putting in air flow vents.

20170102_154203.jpg

My approach is to get the VFD and motor wired and finish up the belt drive conversion so I can use the mill. The second phase is to upgrade to a ESS and spindle control board. My current motor wiring setup should make it fairly simple to get up and running quickly. This is where I can use some help. I have 240VAC single phase coming into the control enclosure. This powers a 24VAC transformer that feeds the motor contactor coil. When I push the power button the contactor latches sending 240VAC through the For/Rev switch to the motor. The attached wiring diagram represents my current wiring with the exception that the head elevation circuitry has been removed as has the X axis power feed circuitry. And my E-stop is now wired into the limit switch circuit.

I have four wires coming out of the For/Rev switch. Can I/should I connect these to the VFD input? If yes, how would I do that? Connecting the motor to the VFD seems simple enough using the attached diagram. L1 connects to U/T1, L2 connects to V/T2 and L3 connects to W/T3 on the VFD. Correct?

20170102_123335.jpg

Not sure how to connect P1 and P2 or if I need to.
20170102_123357.jpg

And last question, at least for now. What Ohm potentiometer do I need? I've seen recommendations for 1K, 2K, 5K and 10K. I have a 50K, a 100K and a 1 megaohm. Will any of these work?

Thanks for your help.

Tom S.
 

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tmarks11

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P1 and P2 are a thermoswitch inside your motor; you are supposed to hook them up so it kills power to the motor if it overheats. The Hitachi WJ200 has connections that are designated for that purpose.
1. Set code C005 to "19" (Page 4-6 "PTC) - (activates thermal protection)
2. P1 and P2 should be hooked between terminal "5" and "L" (page 4-30).

5K or 10K pot will get the job done. You don't want to go much higher than that, since EMI will induce sufficient current to cause unstable response.
1. Set Code A001=00 (Page 3-12) -activates external pot.
2. Connect it between "L" and "O" (page 4-5).

Yes, you want to hook your FWD/REV switch into the VFD. You probably also want to buy an E-Stop button and hook that into the VFD too.
1. Set Code A002 =01 (Page 3-13) - activates terminals for control
2. Lead from the FWD switch terminal to "1" (Page 4-16).
3. Lead from the REV switch terminal to "2"
4. Switch power to "P24"

Not sure what on your switch equates to which position. Basically, when the switch is in FWD, it should allow current to flow from "P24" to "1". When in REV, "P24" to "2".

A couple other points:
1. You will want to set up regenerative braking to slow down faster
2. Make sure that your VFD controller box has good ventilation. That thing can be putting out 100W of heat. You notice in the manual they specify installing it in a box that is at least 4" clearance above,4" below, and an 2" on each side. That might be more than needed, but in the little box you have you might end up having to install a fan to keep ventilation flow (page 2-8).

EDIT: Hitachi, not Fujitsu....
 
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TomS

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P1 and P2 are a thermoswitch inside your motor; you are supposed to hook them up so it kills power to the motor if it overheats.

The Fujitsu WJ200 has connections that are designated for that purpose IIRC; let me take a quick look at the manual and check. Ideally you want the thermoswitch to tell the VFD to shut down.

5K or 10K pot will get the job done. You don't want to go much higher than that, since EMI will induce sufficient current to cause unstable response.

Yes, you want to hook your FWD/REV switch into the VFD. You probably also want to buy an E-Stop button and hook that into the VFD too. Let me check the manual and get back to you.
Thanks. For clarification my VFD is a Hitachi.

Tom S.
 

tmarks11

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typo on my part, meant Hitachi.

Great VFDS; I have two Hitachi WJ200 VFDs: a 2 hp one on my lathe and a 3 hp one on my mill.

Note I went back and looked at the manual and added to my reply above.
 

mksj

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I would recommend a 5K speed pot, the spec. for the WJ200 is 1K, so anything in the 1-5K should be OK. The P1 and P2 are thermostats (P-Stats), alternatively I often connect them either to the E-Stop circuit or there is the inputs/settings to connect them to the WJ200 as noted above, which will shut down and give you an error code. The connections will differ if you use source vs. sink logic. Consideration should be given to if you want the P-Stat to shut down the motor AND also send a stop single to your CNC program, similar to a limit switch. Shutting down the motor in the middle of a cutting sequence could be problematic. It is also possible to use a simple 2 pole 24VAC relay powered through the motor P stat which also provides power to the main power contactor and connect one pole to the the VFD P-Stat contacts and the other to CNC program stop function. Breaking power to the E-Stop, Power or the P-Stat opens turns off which opens the relay and stops the motor, powers down the VFD (this takes about 30 seconds) and sends a stop signal to the CNC program.

I had previously posted a 3 wire connection diagram that can be used with momentary buttons as opposed to 2 wire sustained on to input 1 and 2. It also utilizes the current machine E-Stop system to power down the VFD. A few people have used this on their PM mills. I am a bit unclear if this machine is going to be used for CNC, then the computer/program would control both the direction and speed of the motor directly unless you are manually going to be doing this.
 

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TomS

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I would recommend a 5K speed pot, the spec. for the WJ200 is 1K, so anything in the 1-5K should be OK. The P1 and P2 are thermostats (P-Stats), alternatively I often connect them either to the E-Stop circuit or there is the inputs/settings to connect them to the WJ200 as noted above, which will shut down and give you an error code. The connections will differ if you use source vs. sink logic. Consideration should be given to if you want the P-Stat to shut down the motor AND also send a stop single to your CNC program, similar to a limit switch. Shutting down the motor in the middle of a cutting sequence could be problematic. It is also possible to use a simple 2 pole 24VAC relay powered through the motor P stat which also provides power to the main power contactor and connect one pole to the the VFD P-Stat contacts and the other to CNC program stop function. Breaking power to the E-Stop, Power or the P-Stat opens turns off which opens the relay and stops the motor, powers down the VFD (this takes about 30 seconds) and sends a stop signal to the CNC program.

I had previously posted a 3 wire connection diagram that can be used with momentary buttons as opposed to 2 wire sustained on to input 1 and 2. It also utilizes the current machine E-Stop system to power down the VFD. A few people have used this on their PM mills. I am a bit unclear if this machine is going to be used for CNC, then the computer/program would control both the direction and speed of the motor directly unless you are manually going to be doing this.
 
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