# Precision Matthews PM-728VT CNC conversion



## koenbro

Hello everyone, I have an order on a PM-728VT and is due to deliver within a month. I will do a CNC conversion (with the PM mechanical kit), and will document it here, while also posting the myriad questions that are certain to come up. I am planning to weld up a base for it that will incorporate a toolbox that I already have. I am garage hobbyist and plan to mill aluminum and mild steel mostly.

My experience is with an Avid CNCRouterParts 2x4' extrusion based router that I built, using a 2.2kW air cooled spindle driven by a Delta VFD. The motors are NEMA23 and the controller is a Warp9 ESS; I got the electronics boxes already assembled by Avid. Then I added a THC and a Hypertherm PM-45XP with a water table. I use Fusion 360 and Mach4 with SheetCam for plasma.

For the mill, I have already bought an Acorn with their CNC12 software (paid version).


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## koenbro

Here is my first question: What motors to choose and how to size them? The CNC conversion kit specifies NEMA 23 for axes x and y, and NEMA 34 for axis z.  The ballscrews have a 5mm pitch, the axes lengths are: x-axis = 28”, y = 9”, z =16”, and the diameter is (I think, not sure) 12mm.

I am in touch with Teknic to select the ClearPath servos and they need to know speeds and acceleration (*worst case moving load weight)* on each axis. 

Can somebody help estimate these? Or anyone who has a done a 728 conversion pitch in with their experience and advice? Much appreciate any help.


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## shooter123456

I have a PM-25 which is similar in size.  I use CPM-SDSK-2321S-RLN for the X and Y and CPM-SDSK-3421P-RLN for the Z.  The table with 3 vises mounted will move at 400 IPM and the head does 300 IPM.  The head has an air cylinder and heavier motor as well, so it should be a pretty close comparison if the 728 is slightly heaver.


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## koenbro

That is plenty fast movement! It is this real-life experience that I needed. Thank you much for your reply. 

What materials do you mill? How does this setup perform with (mild) steel?


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## Teknic_Servo

Hi koenbro,

I'm the Teknic applications engineer you've been working with. After coming across this post, I'd like to clarify the specifications that will allow us to recommend the best ClearPath motor for you.

In addition to the screw specifications you've provided, it's helpful to know what you'd like for a maximum load speed (for example, 500 IPM) and how fast you'd like to accelerate the load (for example, 1/4 G). With this, we can recommend the optimal ClearPath and provide the specifications needed for the Acorn controller (i.e. steps/sec and steps/sec^2).

Please give me a call at 585-784-7454, or fill out our contact request form at https://www.teknic.com/contact/ if you have any questions.

-Ian R., Teknic Servo Systems Engineer


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## koenbro

Teknic_Servo said:


> In addition to the screw specifications you've provided, it's helpful to know what you'd like for a maximum load speed (for example, 500 IPM) and how fast you'd like to accelerate the load (for example, 1/4 G). With this, we can recommend the optimal ClearPath and provide the specifications needed for the Acorn controller (i.e. steps/sec and steps/sec^2).



Hello again Ian, and thanks for your dilligent support. As you see, I am trying to do my homework. Based on the CNC experience with my 48x24" router/plasma, I think a *rapid of 400ipm* is more than adequate, and that is before considering the vastly smaller envelope of the mill compared to the plasma table. As for acceleration, I can only guess -- and your starting value of 1/4 g seems ok. Can you please recommend the NEMA 23s for x and y and NEMA34 for z with these parameters?

Second, can we turn the problem on its head? Others seem to have been satisfied with  CPM-SDSK-3432S-RLN for the z axis and  CPM-SDSK-2321S-RLN for x and y. Can you run the simulation on these and tell me the rapids and accelerations? I am looking for the enhanced feature set for all three motors. 

Thank you kindly.


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## Teknic_Servo

Hi koenbro,

After doing some research into the PM-728, I have estimates for the typical load weight and cutting forces for each axis. For a "typically-loaded" PM-728, variants of the ClearPath motors that shooter123456 recommended (CPM-SDSK-2321S-RLN for the X and Y and CPM-SDSK-3421P-RLN for the Z), are a nice fit, depending on your motion goals. These motors will easily provide 600 IPM rapids and 1 G of acceleration on the X and Y axes. The Z will realize 500 IPM rapids and 1/3 G acceleration.

Based on your comments, the specific motor part numbers you may want to consider are CPM-SDSK-2321S-ELS for the X and Y, and CPM-SDSK-3421P-ELS for the Z. There are two differences in these part numbers as compared to those provided by shooter123456.


The *E* (Enhanced) instead of the *R *(Regular) option provides higher commandable machine resolution (0.00003" vs. 0.00025", respectively) and a wider RAS selection (a jerk and jerk derivative smoothing algorithm in ClearPath). For high-precision milling (when paired with good mechanics and a capable controller such as the Acorn), the *E* option may enable an increase in part accuracy and edge quality.
The *S *(additional shaft sealing) versus the *N *(standard shaft sealing) option provides a second seal for additional protection against the environment. If the motor shaft is exposed and the particulate created in the machining process is abrasive, this Viton seal will protect the motor's bearing for the life of the machine.
I'm confident these ClearPath motors will work well with a PM-728 mill. In fact, ClearPath's onboard diagnostic tools allow you to measure on-machine performance, ranging from actual torque usage to tracking accuracy during a cut. Here's a helpful video which goes into greater detail on ClearPath's software oscilloscope capabilities.

Using this tool, you'll know if my motor selection is correct for your specific use case. And if it turns out that the needs of your machine are unique or you'd prefer different motor performance characteristics (such as higher RPM), Teknic offers a 90 day return period during which, if the motors are over/undersized for your needs, you can return them for a full refund through our webstore.

Please let me know if you have any questions.

-Ian R., Teknic Servo Systems Engineer


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## 7milesup

Thanks Ian for being on the forum and giving your insight.
I have, what is most likely, a dumb question.   Can you use the ClearPath servos with Linux controls and software?


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## koenbro

Teknic_Servo said:


> Hi koenbro,
> 
> After doing some research into the PM-728, I have estimates for the typical load weight and cutting forces for each axis. For a "typically-loaded" PM-728, variants of the ClearPath motors that shooter123456 recommended (CPM-SDSK-2321S-RLN for the X and Y and CPM-SDSK-3421P-RLN for the Z), are a nice fit, depending on your motion goals. These motors will easily provide 600 IPM rapids and 1 G of acceleration on the X and Y axes. The Z will realize 500 IPM rapids and 1/3 G acceleration.
> 
> Based on your comments, the specific motor part numbers you may want to consider are CPM-SDSK-2321S-ELS for the X and Y, and CPM-SDSK-3421P-ELS for the Z. There are two differences in these part numbers as compared to those provided by shooter123456.




Thank you Ian, I placed the order in the Teknic online store. I hope I ordered all the right cables with it; I have emailed you the order # in the hope you'd look over the list and let me know if I left anything out. Once I receive the ClearPath package, I will set up the system on the bench with the Acorn prior to mounting it on the mill. Will document my progress here. 

Once again thank you Ian @Teknic_Servo, @jimrk, @kiloseven, and @shooter123456  (hope I did not forget anyone -- apologies if I did) for the advice along the way -- it helped tremendously.


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## Teknic_Servo

7milesup said:


> Thanks Ian for being on the forum and giving your insight.
> I have, what is most likely, a dumb question.   Can you use the ClearPath servos with Linux controls and software?


Hi 7milesup,

Controllers that output 5-24 VDC step and direction commands are compatible with ClearPath-SD. Therefore, if your specific Linux controller outputs digital step and direction signals (see page 152 of the ClearPath user manual for specifications), then it should work well with ClearPath-SD.

FYI, we've had a number of customers successfully use the LinuxCNC controller with ClearPath SD motors.

-Ian R., Teknic Servo Systems Engineer


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## shooter123456

7milesup said:


> Thanks Ian for being on the forum and giving your insight.
> I have, what is most likely, a dumb question.   Can you use the ClearPath servos with Linux controls and software?


Yes you can.  The SDSK just need a step and direction signal.


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## 7milesup

Teknic_Servo said:


> Hi 7milesup,
> 
> Controllers that output 5-24 VDC step and direction commands are compatible with ClearPath-SD. Therefore, if your specific Linux controller outputs digital step and direction signals (see page 152 of the ClearPath user manual for specifications), then it should work well with ClearPath-SD.
> 
> FYI, we've had a number of customers successfully use the LinuxCNC controller with ClearPath SD motors.
> 
> -Ian R., Teknic Servo Systems Engineer


Awesome!  Thank you so much for your reply.


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## koenbro

School me on *enclosures* please. 

I have received confirmation from Teknic that my order has shipped; PM says the mill will ship end-Dec or early Jan. So now I am deciding on the enclosure. 

I plan to put the electronics (Acorn, relay board, Acorn Power supply, Teknic IPC5 power supply, a DIN rail mounted 24V Mean Well power supply), and Teknic DC power distribution hub) into a metal enclosure, attached to the mill. 

Ideally the enclosure will be dust protected and will have an attachment wall for Ethernet in, wall power in (240 and 120V), and connections to the three motors, e-stop and 3 inductive limit stops. The three motor cables (6 cables) will go through the wall through some opening, but the other will attach to the wall with connectors. 

My main experience is with the Avid CNC RouterParts system which has a very nice 400 x 400 x 200 mm steel case and nice connectors on a removable side plate. 

I need advice on *what enclosure,  what size, and which accessories* (ie female-to female ethernet connectors, power in connectors, etc) do you recommend.


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## ptrotter

koenbro said:


> School me on *enclosures* please.
> 
> I have received confirmation from Teknic that my order has shipped; PM says the mill will ship end-Dec or early Jan. So now I am deciding on the enclosure.
> 
> I plan to put the electronics (Acorn, relay board, Acorn Power supply, Teknic IPC5 power supply, a DIN rail mounted 24V Mean Well power supply), and Teknic DC power distribution hub) into a metal enclosure, attached to the mill.
> 
> Ideally the enclosure will be dust protected and will have an attachment wall for Ethernet in, wall power in (240 and 120V), and connections to the three motors, e-stop and 3 inductive limit stops. The three motor cables (6 cables) will go through the wall through some opening, but the other will attach to the wall with connectors.
> 
> My main experience is with the Avid CNC RouterParts system which has a very nice 400 x 400 x 200 mm steel case and nice connectors on a removable side plate.
> 
> I need advice on *what enclosure,  what size, and which accessories* (ie female-to female ethernet connectors, power in connectors, etc) do you recommend.



Check out Automationdirect.com, they have many enclosure options.  Also check cnc4pc.com.


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## coherent

When I was building my CNC machine I did some searching on Amazon and came across a really nice Hoffman 24"x20"x8" steel pull box. Not sure why but the price was only $36 and free prime delivery. Now its $250. I have no clue why you can occasionally find really (really) good deals on Amazon (overstocking? discontinued?) but may be worth a look.  It weighed 35lbs... shipping would have cost me more than I paid for it. The case worked perfectly. I was able to mount a plexiglass standoff board and DIN rails for a professional, clean setup.  Even had room for a VFD in the case.


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## ChrisAttebery

I’m a little late but on my Grizzly G0704 I used 570in/oz NEMA 23 steppers and 5mm pitch screws on all three axis. The machine is capable of high rapid speeds but I keep it set at 120IPM. 

I used a 19” x 8” x 24” rack mount enclosure I bought on eBay. I paid around $100 for it.


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## ptrotter

On my PM-940V VNC conversion I used a Hubbell-Weigmann N41224160C enclosure from Automation Direct https://www.automationdirect.com/ad.../enclosures/wall-mount_enclosures/n412241608c.  I cut large holes is the side where I mounted panels for my connectors.  If I add or change connectors, I only have to replace the panel.  

I used Molex connectors since they match the connectors on the Clearpath servos and I had some.  If I do it again, I would probably use aviation style connectors.

For the Ethernet connection I used: https://www.digikey.com/en/products/detail/harting/09454521504/3974499.  It is a panel mount shielded Ethernet connector with a pigtail.  They make different lengths of pigtails.

Here is what mine looks like:


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## koenbro

ptrotter said:


> On my PM-940V VNC conversion I used a Hubbell-Weigmann N41224160C enclosure from Automation Direct https://www.automationdirect.com/ad.../enclosures/wall-mount_enclosures/n412241608c.  I cut large holes is the side where I mounted panels for my connectors.  If I add or change connectors, I only have to replace the panel.
> 
> I used Molex connectors since they match the connectors on the Clearpath servos and I had some.  If I do it again, I would probably use aviation style connectors.
> 
> For the Ethernet connection I used: https://www.digikey.com/en/products/detail/harting/09454521504/3974499.  It is a panel mount shielded Ethernet connector with a pigtail.  They make different lengths of pigtails.



That's a nice setup -- very similar to what I am going for. Also thanks for the link to the Ethernet bulkhead connector -- I have some female-to-female connectors,  but they are unshielded and will buy the one you have. I was surprized to see that a lot of the enclosure boxes have solid walls -- I would make them with removable panels on at least two walls. So I have ordered a generic box from Amazon with a blank gland plate that I am going to cut with the plasma.

What tool did you use to crimp the Molex connectors?


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## ChrisAttebery

Can


Teknic_Servo said:


> After doing some research into the PM-728, I have estimates for the typical load weight and cutting forces for each axis.



Hi Ian,

Would you mind sharing your weight estimates here?

Thanks,


Chris


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## ChrisAttebery

FWIW: I found a thread where someone had weighed the head and table on a PM-25. The head was ~60lbs and the table was ~67lbs.


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## koenbro

Just a quick update. Still no news of the mill that I ordered in Nov.  Have called PM last Monday: they have received the container from Taiwan, and are going through the back orders in the order they were received. The guy on the phone told me my order will fit into this batch of mills, so I am hopeful to have my toy soon.

In the meantime, have received the complete ClearPath package from Teknic. So today I set out to wire it up on a piece a plywood; added some legs that I cut from an old closet dowel, so cabling can be tucked under. Also attached the motors to a piece of plywood so they don't flop around. After configuring the steps in the Teknic configurator, I managed to wire up one motor following the Acorn schematic. Then I added the contactor, and after I figured that out, added one proximity sensor, that can be tripped and stops the corresponding motor. Very pleased how everything worked out.

I decided I will use 6-pin aviation connectors for the gland plate of the enclosure, instead of Molex.

Still to do:
1. Get NC (normally closed) proximity sensors, instead of the current NO sensors. Small point, but worth it; in case the connection is dropped, you find out before you crash.
2. Need to find sensors that have 4 pin aviation style connectors from the body of the sensor to the enclosure. Will wait until the mill arrives to see the actual physical limitations, and see if I need 90-degree plugs or straight.


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## koenbro

ptrotter said:


> View attachment 348390



Where did you order the Molex connectors? Even though I plan to use aviation connectors for the motor controls, the motor power is a separate molex that I intend to keep.


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## ptrotter

koenbro said:


> Where did you order the Molex connectors? Even though I plan to use aviation connectors for the motor controls, the motor power is a separate molex that I intend to keep.



I buy them from Digi-Key.


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## koenbro




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## cncjoe21

koenbro said:


> Hello everyone, I have an order on a PM-728VT and is due to deliver within a month. I will do a CNC conversion (with the PM mechanical kit), and will document it here, while also posting the myriad questions that are certain to come up. I am planning to weld up a base for it that will incorporate a toolbox that I already have. I am garage hobbyist and plan to mill aluminum and mild steel mostly.
> 
> My experience is with an Avid CNCRouterParts 2x4' extrusion based router that I built, using a 2.2kW air cooled spindle driven by a Delta VFD. The motors are NEMA23 and the controller is a Warp9 ESS; I got the electronics boxes already assembled by Avid. Then I added a THC and a Hypertherm PM-45XP with a water table. I use Fusion 360 and Mach4 with SheetCam for plasma.
> 
> For the mill, I have already bought an Acorn with their CNC12 software (paid version).


Have you started your cnc conversion yet? I just received mine and will be doing the same soon. Hopefully you can share helpful experiences on doing this. Looking forward to following your thread.


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## koenbro

Not yet. I have not yet received the mill and the CNC kit. I have ordered some accessories (vise, collets) and they (QMT/PM) are still waiting for the vises to arrive. Was told it's next week. The mills are already in, but won't ship until the whole order is complete.

Thus far I have configured the Acorn, the motors, 3 sensors (will mount either 3 or 6, and decide once I have the mill), the e-stop, and the contactor. Will still need to buy an enclosure, for the electronics, but want to see what size fits and where, etc.

I am also considering building an enclosure for the mill out of 1010 series 8020. Again, cannot proceed until I have the mill in hand.


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## cncjoe21

koenbro said:


> Not yet. I have not yet received the mill and the CNC kit. I have ordered some accessories (vise, collets) and they are still waiting for the vises to arrive. Was told it's next week. The mills are already in, but won't ship until the whole order is complete.
> 
> Thus far I have configured the Acorn, the motors, 3 sensors (will mount either 3 or 6, and decide once I have the mill), the e-stop, and the contactor. Will still need to buy an enclosure, for the electronics, but want to see what size fits and where, etc.
> 
> I am also considering building an enclosure for the mill out of 1010 series 8020. Again, cannot proceed until I have the mill in hand.


thanks for the reply.  Could you share a ballpark figure of cost for the electronics you already have? I think your idea for an 80/20 enclosure for the mill is a good one.


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## koenbro

The ClearPath package was 1,800. I chose the upper tier motors (enhanced option and shaft seal), but did not go crazy on power; chose CPM-SDSK-3421P-ELS and CPM-SDSK-2321S-ELS. You can save $70 on the NEMA34 and $120 on the NEMA23 (2x$60) from going with motors without the enhancements. If I were to do it again, I might get the one long motor control cable, as I cut off the molex on the acorn side anyways -- so you could shave off a few more dollars if you are familiar with cables (I was not). Would not cut corners on the power supply. In summary, Teknic has a serious product and there are real people behind it, whom you can call on the phone; I would 100% choose Teknic again over some overseas ebay solution.

The acorn package was 299, and that is the absolute minimum you need. I went ahead and ordered the "Pro" mill software ($159), the e-stop button (Made in Italy, superb quality, MUCH better than the one I got with the Avid CNC RouterParts package; thinking of getting a second one for the router) for $45, and the Wireless MPG CNC control pendant for 299. So my total was ~800. Could have stayed with the Mach4 that I already have and get an ESS, but my intuition is that the acorn is a step up for the mill, and it plays nicely with the ClearPath motors.

Got three inductive sensors for $3.60 each off ebay. In fact I ordered three fancy Contrinex sensors from Automation direct for 15/each with nice M12 cables, but picked the wrong sensors that don't work with the acorn. Also got a Made in Germany Eaton DILM32-01 contactor off ebay for 35. Still don't have an enclosure.

So the minimum is about $2,000 ($1600 for the motors + PS, and 299 for the Acorn). My setup is ~2,700 with a few extra conveniences and luxuries.

Still waiting for the mill, though. Hope this helps, and apologies for the delayed reply,


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## koenbro

I have just been notified by PM that my mill is on its way! So hopefully will be in my hands soon. First, will build a base for it, then do the CNC conversion.


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## koenbro

Great news!


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## koenbro

I have a few questions for the base I am about to fabricate: 

1. How high do you prefer to have the bed? I am 5'9" and my workbenches are 36" high and I like that. My drill press table is at around 48" (obviously adjusts up and down a few) and like that also for closeup inspection. So I was thinking the bed should be at around 46-48" high. Any advice?

2. Should I add leveling elastomer/rubber feet or just plain plate steel at the bottom and screw them into the concrete slab (with shimming as needed)?


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## cncjoe21

How is your PM-728VT conversion going? have you been able to put it all together now? will you be posting videos on youtube maybe?


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## koenbro

cncjoe21 said:


> How is your PM-728VT conversion going? have you been able to put it all together now? will you be posting videos on youtube maybe?


I have decided to reverse my initial intent, and do the conversion first, then fabricate a base and enclosure; I wanted to see how wide the x and y extensions are, and where I can mount the coolant tank and its pump.

So I took the mill completely apart, while it was still on its pallet. Because I have never used a mill (or even seen one up close), it took a moment (and some googling) to figure out that the gibbs are asymmetric, and by chance I wedged it tight as I moved the table sideways in an attempt to remove it. Luckily I didn't break or chip anything. Removing the lead screws was easy on axes x and y, but a bit more challenging on the z-axis, because of the 90 degree gears. You have to remove the set screws for the lower gear and a retaining clip on the upper gear before the screw can be removed.


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## koenbro

So after I took it apart,  I hoisted everything on my workbench and started adding the components.







Installing the CNC screws was easy. The factory instructions are very minimal (basically one drawing), but interestingly enough, sufficient. It would have been nicer of course to have step-by-step instructions for somebody inexperienced like me, particularly on how to secure the bearing-retaining precision nuts. On the first try,  I had a large backlash on axis z, so had to remove/reinstall it.


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## cncjoe21

koenbro said:


> I have decided to reverse my initial intent, and do the conversion first, then fabricate a base and enclosure; I wanted to see how wide the x and y extensions are, and where I can mount the coolant tank and its pump.
> 
> So I took the mill completely apart, while it was still on its pallet. Because I have never used a mill (or even seen one up close), it took a moment (and some googling) to figure out that the gibbs are asymmetric, and by chance I wedged it tight as I moved the table sideways in an attempt to remove it. Luckily I didn't break or chip anything. Removing the leadscrews was easy on axes x and y, but a bit more challenging on the z-axis, because of the 90 degree gears. You have to remove the set screws for the lower gear and a retaining clip on the upper gear before the screw can be removed.
> 
> Installing the CNC screws was easy. The factory instructions are very minimal (basically one drawing), but interestingly enough, sufficient. It would have been nicer of course to have step-by-step instructions for somebody inexperienced like me, particularly on how to secure the bearing-retaining precision nuts. On the first try,  I had a large backlash on axis z, so had to remove/reinstall it.


thanks for the info. I have basically done the same. I have replaced all screws and put it back together. Also got my Acorn controller kit but haven't got the motors yet. How do you like the Clearpath servos? I would appreciate it if you provide me a complete list of your electronics items I see in your pictures when you have some time.  I'm a CNC machinist but need to learn more about electronics and components.


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## koenbro

The shaft couplings packaged in the PM CNC kit are a weird choice. All three leadscrews have 10mm ends, so one side of each coupling is 10mm. The other side is however 8mm on two of them (for the NEMA 23 motors for axes x and y), while the third was 14 mm (presumably for the NEMA 23 motor on the z axis. I'd wager that most motors in the US have inch shafts; mine are 3/8" and 1/2", so I ordered from McMaster Carr  the matching ones (2401K14 for 3/8" and 2401K15 for 1/2"). This set me back $147 after I paid ~1K for the conversion kit, so it is not a trivial amount. I think it's odd from PM  to force unto the customer metric couplers that they will probably have to throw away; they could offer a pull-down menu with the right choice, for example, or give the options to not include the couplers in the order). Also I think PM should provide more info on the screws (such as end dia 10mm, pitch 5mm, length, etc) which are needed to calculate motor size etc. 

FWIW these are the useless halves:


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## DavidR8

koenbro said:


> So after I took it apart,  I hoisted everything on my workbench and started adding the components.
> 
> 
> View attachment 356590
> 
> 
> Installing the CNC screws was easy. The factory instructions are very minimal (basically one drawing), but interestingly enough, sufficient. It would have been nicer of course to have step-by-step instructions for somebody inexperienced like me, particularly on how to secure the bearing-retaining precision nuts. On the first try,  I had a large backlash on axis z, so had to remove/reinstall it.


Not to hijack the thread, but curious what CNC router that is in the background.


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## koenbro

Let's talk about sensors.

My Avid CNC Router Pro has Pepperl + Fuchs induction proximity sensors that stop the motors before they can crash. That is what I want to replicate on the mill setup. I am not there yet, but making some progress.

I know nothing about sensors and made a few mistakes I want to share here. First, I ordered some nice Contrinex NO (normally open) PNP sensors off Automation Direct (by the way, I highly recommend automationdirect.com for their high quality products, prompt shipping, great literature, and superb customer service). These don't work, probably because they are PNP; not sure, have returned them.

Then I used some cheapo eBay NO NPN sensors that do work, however there are many reports on the internet about failures after a few months, so I do not want to go the cheapo route. I also wanted to use NC (normally closed) sensors so if there is a wiring issue, they trip and thus alert you of their failure.

After reading up some more, I ordered these sensors (NC NPN), which work.






The way you have to wire them for a normally closed circuit in the Acorn is that the white wire goes to the Acorn input (black wire is unused; brown and blue are as in the diagram):









The factory literature is here, and is useful.


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## koenbro

DavidR8 said:


> Not to hijack the thread, but curious what CNC router that is in the background.


It's the Avid CNC RouterParts 4824 Pro, which I use with the spindle for wood and sheet aluminum, and I also have the water table for plasma.


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## koenbro

There was no easy way to attach the sensors to the casting; tried to drill a hole, but I learned very quickly that that's not going to work. So I decided to reuse the tapped holes for the locking levers on the saddle. I designed a simple bracket in Fusion.





Then cut in on the router out of scrap 1/16" 6061.






Here it is mounted on the mill. The left sided sensor is already on; have added the second (+ limit ) sensor since.






I plan to add two sensors for axis Y and maybe one  for axis Z (upper limit). Still haven't figured out how and where I mount the y-axis sensors, as I want to use existing holes in the casting. 

More importantly, will need to figure out how to configure the Acorn to stop the motors. Right now, it shows on the screen that the sensor is activated, but the motors do not stop.


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## koenbro

cncjoe21 said:


> thanks for the info. I have basically done the same. I have replaced all screws and put it back together. Also got my Acorn controller kit but haven't got the motors yet. How do you like the Clearpath servos? I would appreciate it if you provide me a complete list of your electronics items I see in your pictures when you have some time.  I'm a CNC machinist but need to learn more about electronics and components.


Joe, you have at least the advantage of understanding the machine  part; I know nothing of either the mechanics or electronics. I  am happy to share everything I do so that you can hopefully progress faster and avoid the mistakes I make.

I like the Clearpath servos very much. The product seems great, you get a well-featured, well-thought out package, with great instructional videos and quality support on the phone. They also offer a sophisticated diagnostic software with an oscilloscope built-in; I am not schooled in electronics, so not sure how to use it, but their engineers use it if they need to debug a malfunction on your end.

Here is my order:






I forget one cable so I had to put in a second order. Don't be like me 






The proximity sensor is listed above. The Acorn package is the basic + software + pendant. I think the pendant is a must.

I have not ordered an enclosure box yet, and in fact I might not buy one at all. Instead I will mount the DIN rails and circuit boards on stand-offs on 1/16" aluminum plate, and enclose that in sheet aluminum. Will fabricate a gland plate though, and will use aviation connectors (6 pin for the motors and to control the spindle speed/direction, and 4 pin for the sensors):


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## cncjoe21

koenbro said:


> Joe, you have at least the advantage of understanding the machine  part; I know nothing of either the mechanics or electronics. I  am happy to share everything I do so that you can hopefully progress faster and avoid the mistakes I make.
> 
> I like the Clearpath servos very much. The product seems great, you get a well-featured, well-thought out package, with great instructional videos and quality support on the phone. They also offer a sophisticated diagnostic software with an oscilloscope built-in; I am not schooled in electronics, so not sure how to use it, but their engineers use it if they need to debug a malfunction on your end.
> 
> Here is my order:
> View attachment 356614
> 
> 
> I forget one cable so I had to put in a second order. Don't be like me
> 
> View attachment 356615
> 
> 
> The proximity sensor is listed above. The Acorn package is the basic + software + pendant. I think the pendant is a must.
> 
> I have not ordered an enclosure box yet, and in fact I might not buy one at all. Instead I will mount the DIN rails and circuit boards on stand-offs on 1/16" aluminum plate, and enclose that in sheet aluminum. Will fabricate a gland plate though, and will use aviation connectors (6 pin for the motors and to control the spindle speed/direction, and 4 pin for the sensors):
> 
> View attachment 356620


Thank you so much!! this will be a big help, much appreciated!


----------



## cncjoe21

I believe a counterweight will be needed for the Z-axis. I think the head is too heavy and will put a lot of stress on the Z-axis ballscrew. Any thoughts on that?


----------



## koenbro

cncjoe21 said:


> I believe a counterweight will be needed for the Z-axis. I think the head is too heavy and will put a lot of stress on the Z-axis ballscrew. Any thoughts on that?


OK, the conversion is FAR from ready, but I just had to turn it on and make a few chips even if just to hear it run. When I think about what is left to do, the list seems endless: sort out the electronics,  measure and correct backlash, tram the head, get a real vise (ordered,  promised for late March) and indicate it, add a flood coolant tray, and connect the pump and hoses; finally, make an enclosure and a base. So, not even half-way done! Have not even thought about a counterweight, do you mean a pulley with some weight, or a hydraulic system?

BTW here it is, untrammed, just with a drill press vise, and a bit of scrap, making its first noises:


----------



## cncjoe21

koenbro said:


> OK, the conversion is FAR from ready, but I just had to turn it on and make a few chips even if just to hear it run. When I think about what is left to do, the list seems endless: sort out the electronics,  measure and correct backlash, tram the head, get a real vise (ordered,  promised for late March) and indicate it, add a flood coolant tray, and connect the pump and hoses; finally, make an enclosure and a base. So, not even half-way done! Have not even thought about a counterweight, do you mean a pulley with some weight, or a hydraulic system?
> 
> BTW here it is, untrammed, just with a drill press vise, and a bit of scrap, making its first noises:


I'm thinking pulleys and weight. Did your Z motor lift the head with no problems?


----------



## koenbro

cncjoe21 said:


> I'm thinking pulleys and weight. Did your Z motor lift the head with no problems?


Yeah it does not seem to struggle or anything. When you power it off, it tends to come down though, so I put a piece of 2x4 underneath. A pulley and weight seems reasonable, just not sure how I can hide it. Is there some off the shelf hydraulic system one can add, or is that overcomplicating things?


----------



## cncjoe21

koenbro said:


> Yeah it does not seem to struggle or anything. When you power it off, it tends to come down though, so I put a piece of 2x4 underneath. A pulley and weight seems reasonable, just not sure how I can hide it. Is there some off the shelf hydraulic system one can add, or is that overcomplicating things?


yeah, the z comes down, and had to put a 2x4 as well. I've seen some people run a counterweight with chains and sprockets with linear rails behind the z column, I think I'll go that route.


----------



## koenbro

cncjoe21 said:


> yeah, the z comes down, and had to put a 2x4 as well. I've seen some people run a counterweight with chains and sprockets with linear rails behind the z column, I think I'll go that route.



How far have you gone through the conversion? 


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## cncjoe21

I’ve replaced ball screws and reassembled it but have yet to do the electronics of it. Just ordered the clear path motors and necessary accessories. I have the acorn kit already. Hopefully it won’t take too long until I get my motors and start doing the bench testing so I can finalize it.


----------



## koenbro

Let me ask your thoughts on fixture plates like the SMW  https://saundersmachineworks.com/c...thews-pm-728vt-aluminum-fixture-tooling-plate. 


Should I go for a conventional 4” machine vise (ordered, but can cancel) or a fixture plate with their accessories and small vise? Thanks man. 


Sent from my iPhone using Tapatalk Pro


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## cncjoe21

koenbro said:


> Let me ask your thoughts on fixture plates like the SMW  https://saundersmachineworks.com/collections/smw-fixture-plates/products/precision-matthews-pm-728vt-aluminum-fixture-tooling-plate.
> 
> 
> Should I go for a conventional 4” machine vise (ordered, but can cancel) or a fixture plate with their accessories and small vise? Thanks man.
> 
> 
> Sent from my iPhone using Tapatalk Pro


That's a nice plate to have but it's something you can make yourself later on. I bought 2 5" vises and plan to make a plate similar to the one your referring to which I call "T" plate. I keep the vises on the machine and when I need the plate I use vises to secure it.  Similar to this pic.


----------



## koenbro

I very much like the idea of making it later. What vise do you recommend, as a top of the line hobbyist item — I know it’s like asking about the tallest midget, but I am sure you get what I am saying. 

I looked at the 4” Kurt but at $600 would definitely not be able to afford two. So two at around 250-300 would work with this plan. 


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## DavidR8

koenbro said:


> I very much like the idea of making it later. What vise do you recommend, as a top of the line hobbyist item — I know it’s like asking about the tallest midget, but I am sure you get what I am saying.
> 
> I looked at the 4” Kurt but at $600 would definitely not be able to afford two. So two at around 250-300 would work with this plan.
> 
> 
> Sent from my iPhone using Tapatalk Pro



You might want to check out the Glacern vises. I have a 4” on my mill and it’s really well done.


----------



## cncjoe21

koenbro said:


> I very much like the idea of making it later. What vise do you recommend, as a top of the line hobbyist item — I know it’s like asking about the tallest midget, but I am sure you get what I am saying.
> 
> I looked at the 4” Kurt but at $600 would definitely not be able to afford two. So two at around 250-300 would work with this plan.
> 
> 
> Sent from my iPhone using Tapatalk Pro


I purchased two 5" vises from Precision Matthews and are pretty decent. Not the top of the line but they work.


----------



## jlchapman

I bought the 4" Glacern vise for mine.  I have used a 6" Glacern for the last 5 years on my big mill.


----------



## koenbro

I am very tempted to cancel my current vise order (backordered to 3/26) and get a Glacern 4"  standard vise.

Question: if I want to add a second vise (to hold the fixture plate, for example, or long stock), should I order both upfront and ask Glacern to match their height? Or can I add hte second later and not worry about the possible height discrepancy?


----------



## springer

Check out teco vises too. When I bought my 6" glacern, the teco was similarly priced, maybe a couple $$ cheaper, but I don't remember exactly. Don't get me wrong, I'm happy with the glacern, but when I bought my new mill, the seller gave me 2 teco vises with it. They are much bigger, beefier and heavier. I use all 3 just the same, but I prefer the teco.


----------



## jlchapman

Glacern is having a sale right now.  5% and 10% off.  Just received an email from them.


----------



## koenbro

jlchapman said:


> Glacern is having a sale right now. 5% and 10% off. Just received an email from them.



I went on their website but didn’t see anything about the sale. Meanwhile MSC direct sells the 4 inch Kurt vise for about the same price [500 some dollars] so That’s what I’m going with. I had an order with Kurt themselves who are backordered until late March, while MSC had them in stock, so I switched the order. 

Meanwhile I had emergency surgery last Monday and now I am convalescing at home, but can’t work in the garage and the project is on hold probably for as long as another week. 


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## koenbro

Got the Kurt DX4 and installed, and indicated it. Looks liek a fine piece of kit, although for the price I would have preferred an integral chip shield to protect the lead screw.  The next step will be to fabricate a base for it. 

What suggestions do you have in terms of *anchoring to the concrete floor?* This is a residential garage with a standard, non-tension concrete slab. What diameter screw to use? I am thinking of using 5/16" x 3" Tapcon screws from Home Depot, unless y'allz recommend otherwise.


----------



## Tipton1965

koenbro said:


> What suggestions do you have in terms of *anchoring to the concrete floor?* This is a residential garage with a standard, non-tension concrete slab. What diameter screw to use? I am thinking of using 5/16" x 3" Tapcon screws from Home Depot, unless y'allz recommend otherwise.


I've used wedge anchors many times with great results.


----------



## koenbro

Tipton1965 said:


> I've used wedge anchors many times with great results.


Thank you for the tip, how long and what diameter would you recommend to anchor a machine this size? Is that a non-removable anchor?


----------



## Tipton1965

koenbro said:


> Thank you for the tip, how long and what diameter would you recommend to anchor a machine this size? Is that a non-removable anchor?


I'm using 1/2" diameter to anchor the cabinet on my PM-833TV.


----------



## currinh

koenbro said:


> Thank you for the tip, how long and what diameter would you recommend to anchor a machine this size? Is that a non-removable anchor?


I've been told that you can drill through the slab before installing the anchor. Then if it must be removed you can punch it all the way through the slab into the ground. Just fill the hole with concrete and it's, almost, as good as new. I haven't done this but it makes some sense.

Nice conversion. I got my PM728 conversion up and running around the end of January 2020. Not complete but functional. I'm now on a tangent converting a PM1022 for CNC. I think you are all past the point I can add much but willing to help if I can. I just found your thread.

Thanks.

Hugh


----------



## koenbro

Thanks Hugh, that is very helpful (I have replied to your message).

Here is the current state of the conversion:







I do not have a proper enclosure, have put everything on a 12x12x1/16 piece of 6061, and some 3/4 angle to attach "side walls". Will cover it up with some transparent plastic. Had to remove the side wall where the aviation connectors brought the motor cables, because I rewired those. I had initially cut of the molex connectors and wired directly into the Acorn (via 7/8" 6 pin connectors), but Centroid came out with new wiring recommendatios. So I crimped back the molex spades, ditched the aviation connectors, and attached a CNC4PC ACCP board. The spindle control stil goes thorugh a 6-pin aviation conn. Will need to reconnect the sensors (M12, 4-pin aviation conns), and will rewire the e-stop to another 4 pin. 

Then the KP-3 sensor (that I have on order) will get another 4-pin. Finally I haven't decided yet on a tool height sensor and am not inclined to pay another $700. Is there some easy touch-closes-circuit-trips-relay type solution? My Avid CNC router has a very elegant and reliable system, and really would want smth like it for tool height.

The motor supply will be rewired to get 220V and will get its own box. 

Finally, the coolant pump, and task light will get 3-pin outlets controlled through relays. Took me a while to find the gland plate outlets  (which will go to the bottom wall) but they are on order.







You will notice the illy can in which I keep the mill-specific tools, and the ADM-TPD (antigravity deceleration management table protection device, aka wood block).










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## ptrotter

How did you make the covers for your X and Y servos?  I need to do something similar on my PM-940V conversion.


----------



## koenbro

ptrotter said:


> How did you make the covers for your X and Y servos?  I need to do something similar on my PM-940V conversion.


They came with the PM  CNC conversion kit.


----------



## koenbro

I need some advice re: base fabrication.

I have some leftover 2x1x1/8" steel channel I want to get rid of, so that s my first choice, unless advised otherwise. I will have corner braces to stabilize the structure at the top, one shelf for the coolant pump, and a second one for a drawer, and plates at the bottom to screw anchors into the floor. Plan to weld the rectangular top together, flat and square, but the legs will be screwed to the top  for dampening. The shelves will also be screwed to the legs.

Second, I plan to add a coolant tub, which will have to be about 53" wide and 28" deep. Side walls for the enclosure will be made of 8020 1010 sticks.

Should I make the base just to support the mill, like in the rendering above, or should I bring the front all the way forward under the motor ( the protuberance at the front is the y servo motor, which sticks out 7 1/2" from the base casting)?

I am at an impasse and need your advice with the above.


----------



## currinh

koenbro asked about my PM728 conversion in a PM. I thought it may be of interest to others so I'll post here.

I used the PM kit as everyone here has. It went together very easily, with the only disassembly to pop the head off letting it sit on the table. I used steppers from Automation Technologies, NEMA 23 for X & Y at 425 oz-in and a NEMA 34 for Z at 920 on-in. I found versions with the correct shaft size for the PM shaft connectors. I'm driving these with Gecko G201X stepper drivers and a 70 VDC 1000 watt power supply from Antek. They seem to work well together and have adequate power and speed. I use LinuxCNC paired with an internal Mesa 5i25 card and a Mesa 7i76 breakout board. The computer is a small (I think miniITX) carried over from a Sherline conversion.






I, as yet, have no limit or home switches. I set the machine to its home position manually (jogging) and tell the machine it's home when I start it up, as needed. But generally when I power it down I park the axes at home ready for the next start-up. For this given home position I depend on software limits rather than switches. Not adequate for a commercial product, but for my personal hobby machine it works well for me.

No electronics box yet. I did size the plywood the components are mounted on to fit a standard box though. There's a small relay board at the top (not yet connected) for coolant, etc. I'm not sure if the electronics will mount on the side of the stand or remain on the wall. Time will tell. I bought a CNC speed control board from PM but haven't hooked it up yet. May be nice but speed control from the G-code isn't critical to me.

I built a wooden stand as shown in the picture. It works well and gives some storage. I should have put a solid partition in the middle for support rather than the full width drawers. It sags enough for the top drawer to drag. Will likely be addressed next fall. I built a wooden chip box to catch most of those nasty chips. I did the same on my knee mill and it works very well there. However on the PM728 the shape of the head runs into the box more readily. It's a nice simple solution but I may have to build a full enclosure. I use mist coolant so the box, or enclosure, doesn't have to be water tight.

I hope this gives some idea of my conversion. I'd be glad to address any questions you might have. Thanks.

Hugh


----------



## currinh

koenbro said:


> View attachment 358874
> 
> 
> I need some advice re: base fabrication.
> 
> I have some leftover 2x1x1/8" steel channel I want to get rid of, so that s my first choice, unless advised otherwise. I will have corner braces to stabilize the structure at the top, one shelf for the coolant pump, and a second one for a drawer, and plates at the bottom to screw anchors into the floor. Plan to weld the rectangular top together, flat and square, but the legs will be screwed to the top  for dampening. The shelves will also be screwed to the legs.
> 
> Second, I plan to add a coolant tub, which will have to be about 53" wide and 28" deep. Side walls for the enclosure will be made of 8020 1010 sticks.
> 
> Should I make the base just to support the mill, like in the rendering above, or should I bring the front all the way forward under the motor ( the protuberance at the front is the y servo motor, which sticks out 7 1/2" from the base casting)?
> 
> I am at an impasse and need your advice with the above.


I'd vote for some cross bracing on the sides and back. You could weld the sides up with bracing then bolt to the top with bolted cross bracing on the back.

I think you're planning on an enclosure? If so then plan for this as you build the base. The enclosure could just extend past the base, or the base could extend far enough to be part of the enclosure. Lots of details to consider, but think about the enclosure as you design the base. Just me two cents worth.

Thanks.

Hugh


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## jlchapman

Koenbro,
Awesome drive setup for the encoder  Made me chuckle.  Nothing like coming up with a temporary solution using what you have.  Great way to test components and wiring.  Its also 1 to 1.

I never thought a router could be used on aluminum.  What a great way to make brackets.


----------



## koenbro

How can I use a tool probe on the PM-728? I mean if I put it into an R-8 collet, then swap it out for the mill, the x-y and height info are lost. Is it possible to adapt one holder per tool using BT40 or similar?


----------



## koenbro

jlchapman said:


> Koenbro,
> Awesome drive setup for the encoder  Made me chuckle.  Nothing like coming up with a temporary solution using what you have.  Great way to test components and wiring.  Its also 1 to 1.
> 
> I never thought a router could be used on aluminum.  What a great way to make brackets.


Thank you -- others seem to disapprove of the the axial  attachment  for the encoder, but to me it seems logical and simple. And yes, a router is an awesome way to cut sheet aluminum. I do it all the time with 1/16" and 1/8" 6061;  and have even cut 1/2 plate once, with shallow passes. I prefer a 1/8" one-flute Onsrud carbide mill from McMaster, run at 24,000 RPM and 75 ipm. Very clean edges.


----------



## macardoso

koenbro said:


> How can I use a tool probe on the PM-728? I mean if I put it into an R-8 collet, then swap it out for the mill, the x-y and height info are lost. Is it possible to adapt one holder per tool using BT40 or similar?


Koenbro,

Take a look at the Tormach Tooling System (TTS). It uses a 3/4" master collet and exchangeable tool holders for repeatable Z height and quick clamping.






						TTS - Mill Toolholding - Toolholding - Tooling
					






					tormach.com
				




I have had good success with them. The system is appropriate for spindles up to 10k rpm and not more than 3HP.

For tool holders, there are a wide variety of styles available but you will mostly use set screw holders for weldon shank endmills and ER collet chucks for drills and carbide endmills without weldon shanks.

I have a mix of Tormach genuine and import chucks. They run about $17 per genuine Tormach set screw holder or import collet chuck and $35 for a genuine Tormach collet chuck.

They do add cost to your tooling but are really the best for CNC. Pair it with a pneumatic drawbar and you can change tools in about 1 second with height repeatability to a tenth or so.

I started with 5 ER20 collect chucks (good up to 1/2" tools) maybe 6 years ago and now have almost 30 different holders, drill chuck, boring heads, slitting saws, and electronic edge finders.

Tormach sells a small granite surface plate (6x9") with a hole in the corner to preset your tools off the machine using a height gage. I have this as well and find it to be an excellent method.

I do not own a probe, but I have a 3D edge finder (one of the electronic ones with a ball tip) and use that as my master. Once a part is zeroed with that, all my tool lengths will be spot on.

The import chucks are good quality (once you reject any obviously bad ones) but I strongly suggest paying the extra bit for Teknics ER collets. Import collets are just no good for runout.

I show these a few times in the build log for my mill. Here is one post regarding them and the pneumatic drawbar.









						G0704 CNC AC Servo Rebuild (Picture Heavy)
					

The machine is now as good or even better then when I started this upgrade. I am going to hold off on actual machining for a little bit, but if I need to use it, it is ready to go!




					www.hobby-machinist.com
				




-Mike


----------



## jlchapman

macardoso, I'm also converting a PM728(should be here this week) to cnc.  I bought the Lyndex TTS collet adapter, bunch of ER20 collet chucks, superfly, drill chucks, granite plate and engraver from Tormach.  Tormach has received alot of money from me.  But one thing with machining is your going to spend alot on tooling.  That part never stops.  

I'm also a firm believer in the Teknics ER collets, I use those in my big mill. Pneumatic drawbar is definitely on my radar and will happen at some point.

I've bought some end mills.  Mostly YG1 alu-power 3-flute 45 degree,  1/8", 1/4", and 1/2".  I've bought all square end.  What have you found you need for ball end mills?  What size end mills do you mostly use?  Any other end mills you recommend?

I skimmed through your build.  Nice build.  Enclosure is great.  I would expect nothing less from somebody that works with Allen Bradley equipment.  I have one of there Micro800 series PLC's in my extra parts.

Jerry


----------



## ptrotter

Check the runout on your Lyndex R8 Collet.  I have 2 R8 collets for my TTS tools.  One is Lyndex labeled and one is Tormach labeled, both of which I bought from Tormach. The Lyndex has so much runout it is basically unusable, whereas the Tormach is excellent, as good as my Hardindge collets.


----------



## jlchapman

Thanks Paul.  I'll check that.  I bought my Lyndex from Tormach.


----------



## macardoso

jlchapman said:


> macardoso, I'm also converting a PM728(should be here this week) to cnc.  I bought the Lyndex TTS collet adapter, bunch of ER20 collet chucks, superfly, drill chucks, granite plate and engraver from Tormach.  Tormach has received alot of money from me.  But one thing with machining is your going to spend alot on tooling.  That part never stops.
> 
> I'm also a firm believer in the Teknics ER collets, I use those in my big mill. Pneumatic drawbar is definitely on my radar and will happen at some point.
> 
> I've bought some end mills.  Mostly YG1 alu-power 3-flute 45 degree,  1/8", 1/4", and 1/2".  I've bought all square end.  What have you found you need for ball end mills?  What size end mills do you mostly use?  Any other end mills you recommend?
> 
> I skimmed through your build.  Nice build.  Enclosure is great.  I would expect nothing less from somebody that works with Allen Bradley equipment.  I have one of there Micro800 series PLC's in my extra parts.
> 
> Jerry



I've found the Tormach tooling to be quite nice. The Chinese knockoffs are hit and miss, but I've always had a good outcome of receiving the correct number of chucks in specification, even if I have to argue with the seller to make it right. 

I've only ever used the Tormach branded TTS collet and it has been as good as the somewhat crappy spindle of my mill. The pneumatic drawbar was a bit of work to build but has performed perfectly with no adjustments since.

I have a G0704 and after LOTS of testing, I feel the mill is properly sized to utilize 3/8" cutters in aluminum and 1/4" cutters in steel. Nothing is stopping you from loading up a 3/4" endmill but you will suffer with the rigidity problems that come from the larger diameter. I rarely use a ball endmill for my work. I keep one 1/4" ball endmill in the tool rack. With ball endmills, you trade off with surface finish (larger is better) for feature definition (smaller is better).

I love the YG-1 ALU Power endmill. My main tool for aluminum is a 3/8" standard length cutter and I've gotten about 4 years of lifespan out of it. If you can use a roughing tool and then come back with a finisher, the serrated roughing endmills are great for reducing HP and side load on tools which helps these smaller machines.

Thanks for the compliments  AB makes nice stuff.


----------



## tq60

I hate wedge anchors.

Not removable and you lift the machine to move it.

Drop in type works well.

Our shop was built with what looks like lag bolts for concrete, real easy, drill hole, blow out dust and insert screw.

Rated stronger than the wedge too.

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## Weldingrod1

You can epoxy threaded sleeves into the floor. There are also female threaded anchor out there; I used some on my garage door hurricane braces.

Sent from my SM-G892A using Tapatalk


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## koenbro

Thank you all for the replies. I had a couple of weeks of downtime because of an emergency surgery, then returned to work, so the mill conversion was on a temporary hiatus.

*MILL BASE*.  
I am back now, and have built the base. When I built my CNC router, I used 2x2x.08" tube and welded it all up. Even though I used spot welds in opposite corners, and squared up meticulously everything, etc., heat distortion kicked in, and had to cut up some welds and redo them at the end, to square up everything. I still feel that base is not rigid enough, and will bolt into the ground hoping to improve it; overall, am not very worried about it, as the forces with the router are pretty limited, and with plasma are pretty negligible.

This time I want to make it rigid though, so chose to use an open profile with some corner bracing.  Would have used angle if I had enough; although probably not optimal, I ended up using using a 2x1x1/8" channel I had around (and wanted to get rid of) for the top and legs:













I also built a mid-level shelf out of 1.5x1/8" angle to put the coolant tank and pump on:
















Finally, I built a bottom shelf using 1x1/8" angle. All this was scrap laying around, happy to get rid of.

Have decided to bolt it all together with 5/16" bolts mostly (1/4" for the lower shelf and for alignment at top) hoping to get improved dampening, and avoid welding and thus distortion. Will see how it works. here it is during one of the intermediate fitment checks:







Ignore the stiff drink in the image above. Be smarter than me, and do not drink and weld, or you'll end up having welds like mine ;-)


Now all parts are in the backyard, drying its (hopefully) final coat of paint and will assemble it later today.

The base ended up pretty heavy;  will bolt it into the concrete floor, hoping it will suffice. Thank you all for the advice above, I will go with 5/16" Tapcons (at least in the first round).


----------



## koenbro

*COOLANT TRAY*
Next to build a coolant tray. I initially wanted a sloping on with lowest spot in the center, with a drain, but am thinking going simple with a plain rectangular tub, 53" wide, 28" deep, and 4" high. I can cut it all from one piece and just bend the side and will have 4 short 4" corner welds. Will use 1/16" aluminum sheet.

I do not have a sheet metal brake, so give me advice on how to make the bends. Even if I were to buy a brake it will be max 48" long so will not fit the 53" length. One option I am considering is using angle iron clamped to the corner of a bench and hamering it up. Maybe run a cut on the inside surface to remove 30% thickness of the material and give a guideline for the bend. Any thoughts?


----------



## koenbro

macardoso said:


> I've found the Tormach tooling to be quite nice. The Chinese knockoffs are hit and miss, but I've always had a good outcome of receiving the correct number of chucks in specification, even if I have to argue with the seller to make it right.
> 
> I've only ever used the Tormach branded TTS collet and it has been as good as the somewhat crappy spindle of my mill. The pneumatic drawbar was a bit of work to build but has performed perfectly with no adjustments since.
> 
> I have a G0704 and after LOTS of testing, I feel the mill is properly sized to utilize 3/8" cutters in aluminum and 1/4" cutters in steel. Nothing is stopping you from loading up a 3/4" endmill but you will suffer with the rigidity problems that come from the larger diameter. I rarely use a ball endmill for my work. I keep one 1/4" ball endmill in the tool rack. With ball endmills, you trade off with surface finish (larger is better) for feature definition (smaller is better).
> 
> I love the YG-1 ALU Power endmill. My main tool for aluminum is a 3/8" standard length cutter and I've gotten about 4 years of lifespan out of it. If you can use a roughing tool and then come back with a finisher, the serrated roughing endmills are great for reducing HP and side load on tools which helps these smaller machines.
> 
> Thanks for the compliments  AB makes nice stuff.


*TOOLING EXCHANGE*
I read your thread: very impressive. I am looking at the Tormach tooling system. So let me get this straight. You insert the Lyndex R8-to-TTS adaptor collet and leave in, and keep your cutters in individual TTS threaded arbors that you then swap  in and out ? Or do you use ER20 collets? Sorry for being slow here, just want to understand how to do fast cutter swaps.


----------



## koenbro

So I finished the base and have attached it to the floor. Needed some shims because the floor sloped down (and the base itself was probably out of square also) so I cut a few more feet; the front right needed two 1/8", the back right one 1/8 and one 1/16, the front left on 1/8 nad the rear left nothing. It leveled out within bubble tolerances.

Then, with the help of a few 1/2" pipes, my wife and I transferred the mill from the workbench it sat on so far, to the base. It went very easily. Of course, I will have to lift it when the coolant tray is ready, But for now I am happy it's in its (almost) final place. Will run the Teknic Auto-tune again and use the highest speeds, to see how the base tolerates it. Every one of its legs is connected with 7 screws to the top or the shelves, and 2 more screws to the floor (two screws attaching the lower shelf still need to be added, like in the bottom left of the photo). Seems sturdy enough to me, but will see.


----------



## koenbro

Here it is as I am drilling the base and using shims (=copies of the legs base).


----------



## macardoso

koenbro said:


> *TOOLING EXCHANGE*
> I read your thread: very impressive. I am looking at the Tormach tooling system. So let me get this straight. You insert the Lyndex R8-to-TTS adaptor collet and leave in, and keep your cutters in individual TTS threaded arbors that you then swap  in and out ? Or do you use ER20 collets? Sorry for being slow here, just want to understand how to do fast cutter swaps.


Thanks!

Bingo. You leave the 3/4" R8 collet in the spindle (it is a modified R8 collet with a flat face rather than the traditional rounded one - you can modify your own in a pinch). Your tools are held in tool holders with 3/4" straight shanks and a 1-3/8" diameter collar. The gripping force of the collet both grabs the shank of the tool holder and pulls the collar into contact with the spindle nose. This causes repeatable Z depth and moderately strong clamping. You can use a standard drawbar with this method, however it is also well suited for pneumatic drawbars for rapid tool change.

The downside is the investment in the tool holders. You have one for each tool in your program. If you run small to medium batch work then you can get by with a couple holders, however if you do job shop or project work where you use a ton of different tools, you'll find you want more holders so you aren't swapping tools in and out of the holders so often.

Holders are available from Tormach and import sources (eBay). The holders I know exist:

ER16/20/32 collet chucks  (I have a bunch of ER20)
Setscrew holders (1/4" - 1/2", 4mm-12mm)  (These are very economical, only good for weldon shank endmills though)
Drill chucks
Modular Indexable tools
Shell/face mills
Slitting Saws
Boring head
Rotary Broaching
Tension/Compression tapping
Fly Cutter
Drag Knife
Diamond engraving
Electronic Probes
Various Measuring tools
If you want to try them, I'd suggest maybe 5 holders to start. If you like the system, then you can grow to your needs. The offline tool setting is a game changer for me. Between that and the pneumatic drawbar, I spend almost no time changing tools on the machine and they repeat within a tenth or two. More accurately than my machine for sure.

If you buy ER collet chucks, you'll also need a good variety of ER collets. With my G0704, I much prefer holding drills in ER chucks over drill chucks due to the better concentricity and lower Z height (don't have much on my machine). I bought a bunch of cheap eBay ER collets and they are consistently garbage. I have had awesome results with Techniks collets. Not cheap ($10 each or so) but they do hold their 0.0004" or better tolerance. 

Once a commonly tool is set up for height and minimal runout, then it can live in the holder until you break it.


----------



## macardoso

Great work on your build! Can't wait to hear your thoughts on the performance of the machine. I'd be a touch worried about the stand swaying along the X axis, but will be interested to hear your analysis.


----------



## macardoso

koenbro said:


> Yeah it does not seem to struggle or anything. When you power it off, it tends to come down though, so I put a piece of 2x4 underneath. A pulley and weight seems reasonable, just not sure how I can hide it. Is there some off the shelf hydraulic system one can add, or is that overcomplicating things?


Haven't seen if this was answered, but constant force gas springs are a great option for this. I have one on my G0704 adding 50lbs of lifting force to the head.

You have to pick one with the appropriate stroke length (longer than your usable Z travel) and a reasonable overall length. I had to fabricate two simple brackets to add it to the mill.









						McMaster-Carr
					

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.




					www.mcmaster.com
				




You can see it on the left of the column slide in this image.


----------



## koenbro

macardoso said:


> Haven't seen if this was answered, but constant force gas springs are a great option for this. I have one on my G0704 adding 50lbs of lifting force to the head.
> 
> You have to pick one with the appropriate stroke length (longer than your usable Z travel) and a reasonable overall length. I had to fabricate two simple brackets to add it to the mill.
> 
> 
> 
> 
> 
> 
> 
> 
> 
> McMaster-Carr
> 
> 
> McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
> 
> 
> 
> 
> www.mcmaster.com
> 
> 
> 
> 
> 
> You can see it on the left of the column slide in this image.


Thanks for that tip and the McMaster link. Which item did you choose? (perhaps you have the item # 4138Txx?). I will probably go that route too.


----------



## koenbro

macardoso said:


> Great work on your build! Can't wait to hear your thoughts on the performance of the machine. I'd be a touch worried about the stand swaying along the X axis, but will be interested to hear your analysis.


BASE UPDATE:
So I tested the mill, and on x-axis rapid, it sways like a poplar tree in the wind, although the rapids are smooth and precise. The y-axis rapids show some vibration too, but the sound is different. Will try to take a video.

In fairness, this base is a FAIL, and let this be a cautionary tale to others.

Before I put the mill on it, it felt really sturdy as I tried to budge it; maybe I need to lift more, or maybe the ClearPath servos and  the mill bed's weight and momentum unleash forces I did not anticipate. So I have ground off the freshly applied paint in the top corners and weld the legs to the top; my theory of bolts providing dampening didn't really work out. Will test it again, and decide on braces, and welding the top shelf (middle level) also to the legs.


----------



## koenbro

SPINDLE CONTROL
Meanwhile I replaced PM's 0-10V factory spindle control board with a KB ELECTRONICS KBSI-240D signal isolator. The PM factory board was not giving a linear spindle response, at least not with the Acorn. As I tested it with a voltmeter, Acorn's output was nicely linear in the desired speed range. The spindle response was higher but not with a constant rate, and the board does not have a pot to fine tune. Now I get decent reponse to spindle speed g-code.


----------



## Weldingrod1

You need cross braces!!! X the back (top to bottom) and run an brace across the right and left sides. Think about an X brace under your shelf too.
For an X, it can be flat bar and doesnt need to be super huge or thick. 2"x1/4" will be verging on overkill. 1/8" thick.is.probably plenty too. A single cross bar wants to be able to be pushed on, so consider squate or rectangular tubing for that. Bolting the braces will add some damping, but however you attach it, get it solid. If its bolts, torque it like you mean it!

Fyi, open sections like angles and channels are MUCH easier to twist than closed ones. Your router table was a better design for stiffness!

Sent from my SM-G892A using Tapatalk


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## macardoso

koenbro said:


> Thanks for that tip and the McMaster link. Which item did you choose? (perhaps you have the item # 4138Txx?). I will probably go that route too.


I'm not 100% sure since it was a good few years ago, but I think it was 4138T61 with a 50 lbf gas fill. My G0704 has about 9" of usable Z travel with the way covers installed so 10.24" of stroke would have covered it.


----------



## koenbro

Making slow progress. Have replaced the PM 0-10V spindle speed controller (which I couldn’t make work and is not tunable) with a proper isolator KBSI 240D isolator which works well.


Then started work on the enclosure:








It’s made of 1010 and plan to use slide in panels on the back, curtain-like strips on the sides to allow full movements in the x axis ( and accommodate long stock), and even plan to enclose the top. As for the front, am thinking a hinged door that swings upwards.

Its overall outside dimensions are: 48"W x 31"D x 28"H. Looking at the 8020 catalog now to decide on the hinge, slide-in panels, and locks (if any). Then the hard part of making a tray comes next.


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## koenbro




----------



## pdentrem

I would do a sliding front door. Either one piece or split left and right. A lift door is a head banger.
Pierre


----------



## rwm

I agree. Add 1010 strips to the front top and bottom and use dual sliding doors.
Robert


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## jlchapman

Nice progress on the enclosure!

What did you get for backlash on your 3 axis?


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## koenbro

jlchapman said:


> Nice progress on the enclosure!
> 
> What did you get for backlash on your 3 axis?


I don't know how to properly test backlash, but would like to measure it. Do you have a method you recommend?


----------



## jlchapman

koenbro said:


> I don;t know how to properly test backlash, but would like to measure it. Do you have a method you recommend?


I’ll send you a link when I get home.  Marty did an awesome write up


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## jlchapman

Here is a good video on Overall Ratio Calculator:  https://centroidcncforum.com/viewtopic.php?f=61&t=1449&start=10

Here is the backlash information:  https://centroidcncforum.com/viewtopic.php?f=63&t=1801

Backlash is the very last post, but the whole topic is a good read.

All these adjustments are necessary and alot easier to do before everything is enclosed.

I had on the x-axis  almost .009 thousandth before I made my adjustments down to .0010 to .0013.  The article also tells how to compensate in CNC12 for up to .0015 backlash.

Have you used your KP-3 yet?  I almost pull the trigger everyday but I wanted to wait and get the machine setup properly first.  I have a Haimer, but until I really know CNC12 and the commands, I wont use it.  To easy to break probes and expensive to replace.


----------



## sakumar

koenbro said:


> Yeah it does not seem to struggle or anything. When you power it off, it tends to come down though, so I put a piece of 2x4 underneath. A pulley and weight seems reasonable, just not sure how I can hide it. Is there some off the shelf hydraulic system one can add, or is that overcomplicating things?


A couple of weeks ago Marty (of martyscncgarage) posted a video on YouTube showing how to install a z-axis electric brake. This is a device that goes between the servo and the ballscrew and is locked when in a power-off condition. With a signal from the CNC board, it unlocks the z-axis.

This seems like a pretty good solution for the problem of the machine head coming down when the z-axis servo is powered down. It won't provide assistance to the servo motor during normal operation though, but you noted that the motor is powerful enough.

I enquired with Teknic support and Teknic will be offering this product as an OEM in a few weeks. It is currently available direct from the manufacturer.


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## jlchapman

Sakumar,  I watched the video and called Teknic also.  They sent an email to the manufacturer for me, but I havent heard from them.  I think I'll wait until Teknic is carrying it.  Nice solution, but expect it to cost around $350.


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## koenbro

I have removed the enclosure to fix the base and check the backlash as recommended above. Am getting some 22GA steel sheet later in the week to make a tray. *What kind of drain and diameter do you recommend*? Will 1" be enough, or should I go for a shower-style 2" drain?

What coolant do you recommend for this application?

Still figuring out what kind of 8020 components I need for the sliding door. Thinking about this one (and its corresponding upper) versus the dual roller wheel assembly, or combining them: roller assy on top, and track on bottom?


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## koenbro

jlchapman said:


> Here is a good video on Overall Ratio Calculator:  https://centroidcncforum.com/viewtopic.php?f=61&t=1449&start=10
> 
> Here is the backlash information:  https://centroidcncforum.com/viewtopic.php?f=63&t=1801
> 
> Backlash is the very last post, but the whole topic is a good read.
> 
> All these adjustments are necessary and alot easier to do before everything is enclosed.
> 
> I had on the x-axis  almost .009 thousandth before I made my adjustments down to .0010 to .0013.  The article also tells how to compensate in CNC12 for up to .0015 backlash.
> 
> Have you used your KP-3 yet?  I almost pull the trigger everyday but I wanted to wait and get the machine setup properly first.  I have a Haimer, but until I really know CNC12 and the commands, I wont use it.  To easy to break probes and expensive to replace.


That is very useful, thank you, I will test the backlash and report back.


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## sakumar

jlchapman said:


> Sakumar,  I watched the video and called Teknic also.  They sent an email to the manufacturer for me, but I havent heard from them.  I think I'll wait until Teknic is carrying it.  Nice solution, but expect it to cost around $350.


jlchapman, I finally heard back from the z-axis brake manufacturer (Newstart Motion). They quoted $400 -- including shipping from China.


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## koenbro

sakumar said:


> jlchapman, I finally heard back from the z-axis brake manufacturer (Newstart Motion). They quoted $400 -- including shipping from China.


I very much doubt that I'll ever spend 400 dollars on a brake when I can just slip a piece of wood under the head.


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## sakumar

koenbro said:


> I very much doubt that I'll ever spend 400 dollars on a brake when I can just slip a piece of wood under the head.


You're probably right. I worried about scenarios where there's a power failure and the self-lowering head gouges through a part, or the table or worse. Or if I forget to place the wood and it breaks a KP-3 probe or perhaps a Haimer tip. Definitely an expensive solution though but since Teknic are going to OEM it, I feel reassured about the quality.


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## jlchapman

I'm going to wait and see if teknic carries the brake.  Will have to be cheaper to get me interested.


----------



## cxagent

GREAT Thread!!! I am working on the conversion of my PM728VT as well. It has stopped for the moment because I can't get it done and tested in time to make some parts needed by mid-May. I will have to make those parts manually instead of CNC.

I will post some pictures and such later. I really appreciate learning from others!


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## cxagent

Picture of the CNC control box about half way wired. All 4 stepper drives are at lower right. Two large power supplies (36 & 48V) are at the upper right. Acorn power supply, Acorn board and Acorn relay board are at left. Fans are at the left side which will become the bottom. Outlets are at the right in the picture (will be top).

The box is 18x18x6. If I had it to do over I would go with a slightly larger box (20x20 would help a lot). I got it all in there but it is tight. I had to stack the two large power supplies so I added a heat sink to the 36V and bolted it to the aluminum base plate.

I keep thinking I will 'finish it this weekend' but then something comes up and I don't get much if any time to work on it.


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## koenbro

After a long break for a number of reasons, I am back with the conversion. 

Have bought a Rittal 24 x 20 x 8 enclosure and laying the parts onto it. 

Not sure how to make the cutouts for switches and cables. At the bottom will use a Centroid access pressure plate but the sides remain TBD. 

Here is the layout:







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## koenbro

In the box. 


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## cncjoe21

koenbro said:


> In the box.
> 
> 
> Sent from my iPhone using Tapatalk Pro


Very nice! Would like to see more when the wiring is done


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## cxagent

Looking good!

I priced punches to make all of the switch and connector holes in the sides of the box. That was WAY too expensive - ~$1000. I made my own punches for the small holes. I bought plates from L-com for the D-sub connectors. I used a nibbler to make the larger holes. I can post pictures & links later if it would help.

I added some pictures and below this paragraph.

Connector plates from L-com https://www.l-com.com/patch-panel-s...bXCSSqVq3_QG4j9DQp3KuB4XMG0Gg_AkaAmkpEALw_wcB

I made the punch form 12L14 steel (weak but it is what I had available then). The outer sleeve is fine with the low grade steel. I made the inner part by turning the OD and threading the ID. The "punch" was made by plunging a 1" diameter end mill "sideways" across the 5/8" diameter. That created the points to bite into and shear the part being punched. I did not try to harden the 12L14 at all. It did all 12 the holes I needed with only the initial build and one sharpening.

Larger holes were all made with the Nibbler. I tried a hole saw but the results were crappy. The hole saw cuts thru but it wobbles and leaves a wide kerf with a nasty ragged edge. The nibbler took some practice to set up but gave a much better & cleaner cut.

Last is a picture of the connector side of the CNC box. I labeled everything with a label maker since I didn't have a CNC to make nice nameplates. Also shown are the results of mounting the D-sub connector plates I got from L-com inside the housing. If I had a punch or a CNC I could make the cutouts for the DB-9 or DB-15 connectors myself. I am building the CNC so I don't have it yet. And the punch was several hundred dollars. The plates were about $10 each if my memory is correct.


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## pdentrem

Use the step drills that every store seem to sell. Can go from 1/8” to 1 1/4” in 3 bits.
Pierre


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## koenbro

cxagent said:


> Looking good!
> 
> I priced punches to make all of the switch and connector holes in the sides of the box. That was WAY too expensive - ~$1000. I made my own punches for the small holes. I bought plates from L-com for the D-sub connectors. I used a nibbler to make the larger holes. I can post pictures & links later if it would help.
> 
> I added some pictures and below this paragraph.
> 
> Connector plates from L-com https://www.l-com.com/patch-panel-s...bXCSSqVq3_QG4j9DQp3KuB4XMG0Gg_AkaAmkpEALw_wcB
> 
> I made the punch form 12L14 steel (weak but it is what I had available then). The outer sleeve is fine with the low grade steel. I made the inner part by turning the OD and threading the ID. The "punch" was made by plunging a 1" diameter end mill "sideways" across the 5/8" diameter. That created the points to bite into and shear the part being punched. I did not try to harden the 12L14 at all. It did all 12 the holes I needed with only the initial build and one sharpening.
> 
> Larger holes were all made with the Nibbler. I tried a hole saw but the results were crappy. The hole saw cuts thru but it wobbles and leaves a wide kerf with a nasty ragged edge. The nibbler took some practice to set up but gave a much better & cleaner cut.
> 
> Last is a picture of the connector side of the CNC box. I labeled everything with a label maker since I didn't have a CNC to make nice nameplates. Also shown are the results of mounting the D-sub connector plates I got from L-com inside the housing. If I had a punch or a CNC I could make the cutouts for the DB-9 or DB-15 connectors myself. I am building the CNC so I don't have it yet. And the punch was several hundred dollars. The plates were about $10 each if my memory is correct.


Thank you for the very useful info. I very much like the neat connect plate photo. That is something I am trying to achieve. Didnt go the punch route, but I have a plasma, so I cut out an 1" swide, 10" long slot for cable access and a larger opening on the left wall for power input. Finally drilled two holes on the right wall, using the step-up bit @pdentrem recommended. Turns out the 7/8" is perfect for the e-stop and on-off switch.

For the gland plate, I used 1/16" 6061 which I cut out with my router to accommodate various cables. I am very pleased with how it turned out.


----------



## koenbro

cncjoe21 said:


> Very nice! Would like to see more when the wiring is done



Here is the box completely wired. 


















The bottom wall:







And this is the right sided-wall, which will face the operator, as I plan to add the box to the left side of the mill base:


----------



## koenbro

Most importantly, I connected everything back to the mill and it does work. Have wired in and configured the KP-3 probe. The spindle control is also all wired but will need to test it and then, the enclosure and electronics are done!!

Will re-do the base though as it is very wobbly, using 2 or 3" square tube.  Next, will add an enclosure with a tray so I can run coolant. Finally will add an air ratchet for PDB. So frankly still lots to do.


----------



## cxagent

Looking Great!

Please keep posting pictures of your progress.  I really want to see how you run coolant. I don't have a plan for coolant yet.

Unfortunately, mine is still sitting there untouched.


----------



## koenbro

Can anyone guide me to a replacement bellows (accordion) -style way covers for both the z-and y-axes. The PM originals are pathetic.







I need some bellows for the 4" Kurt vise while I am at it. Thank you all.


----------



## Weldingrod1

I use heavy weave fiberglass cloth that is either soaked in plasti-dip (version 1) or silicone caulk diluted with mineral spirits (version 2, still to be tested).

Sent from my SM-G892A using Tapatalk


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## koenbro

Weldingrod1 said:


> I use heavy weave fiberglass cloth that is either soaked in plasti-dip (version 1) or silicone caulk diluted with mineral spirits (version 2, still to be tested).
> 
> Sent from my SM-G892A using Tapatalk


I was thinking more along these lines:

https://www.mcmaster.com/bellows-covers/three-sided-flat-bellows-7/


----------



## pdentrem

On the vise I use a simple magnetic sheet. Works great. The bellows should be good.
pierre


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## koenbro

With the electronics enclosure finished, I started today to make the mill stand version 2. The first version is very flexible in the x axis, so I decided to use 3x3x1/8" tube and will make the base 30" wide, 30" deep and 33" high. Basically a cube. Hopefully will be lots more rigid. Also considering filling the tubes with sand. So I cut the elements into 30" and 24" bits:
















And will put in some holes to attach the mill before welding together tomorrow.


----------



## koenbro

Slow progress, but progress, with the base. Its skeleton is finished. Added tabs on the left to attach the control box and will add some in the front and back to attach the 8020 enclosure. Will fill it with sand to add nonresonant mass. 







Front is on the right:





This is the back and right side:






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## koenbro

Wondering if a 30” structure of 3” tube needs diagonal bracing?


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----------



## pdentrem

I would wonder as well if the 3“ tubes are enough. Seems likely to be strudy. Uline sells metal tables of similar design and they are very stiff but we are not moving heavy weights at high speed either.
Pierre


----------



## koenbro

Today I added four tabs to support the enclosure. The front ones protrude to the side and are not mechanically strong although they will not have to bear weight; can always add a buttress below if needed:






The rear ones will support weight:






And this is how the mock-up enclosure looks now although i will probably modify it to allow my HF 5-drawer mechanic tool cart to slide under (space is a critical shortage in my one-car space in the 3-car garage): 







The front is on the right and will have two sliding half doors. 






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## koenbro

I made two trays out of 25 gauge sheet metal that will collect the coolant. Here i am fitting them in. 


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----------



## kb58

It makes me happy to see a Porsche owner cutting, machining, and welding. There is hope


----------



## koenbro

Haha, thanks -- some of us are enthusiasts! That is my daily driver -- 2007 with 90-some thousand miles, barely broken in. The 2001 Tacoma is the weekend ride, and I plan to use my basic garaging/machinist skills (and the NEW mill) to build her up as an overland rig.


----------



## sunrise305

koenbro said:


> Great news!
> 
> View attachment 354959
> 
> 
> View attachment 354961
> 
> 
> View attachment 354963


I just posted a question about delivery of the same mill.  Was the driver willing to roll it across your Belgium block driveway?  I have the same driveway material and am wondering if the pallet jack will roll across it.


----------



## koenbro

sunrise305 said:


> I just posted a question about delivery of the same mill.  Was the driver willing to roll it across your Belgium block driveway?  I have the same driveway material and am wondering if the pallet jack will roll across it.


Yes, he brought it all the way into my garage. The driveway is about 30-50 yds with about 10ft elevation gain, yet he did it. This was the only way I could begin working on it.


----------



## sunrise305

koenbro said:


> Yes, he brought it all the way into my garage. The driveway is about 30-50 yds with 10-15ft elevation gain, yet he did it. This was the only way I could begin working on it.


Great news!  Thank you.  Mine is Belgium block about 50 feet long with a 3-4 foot grade.  So hopefully I should be fine.


----------



## koenbro

After a few weeks of distractions with work, family, a new (to me) pick up truck that needed attention, I am returning to this project. Have started by filling the tubes with play sand. The sand that Lowe’s sells comes in plastic bags and it is wet, so I could not use it. Got some Sacrete brand from HD that came in paper bags and was dry.







Then hammered in some 1.5 x 1.5 plugs:





And have thus added about 120 lbs of non-resonant mass:





To recap it is 3x3x1/8” tube, sized 30x30x33-½” and bolted to the slab with 3/8” tapcom. Estimate the  weight of the base at around 150#,  and with sand at about 270# total.





Very happy with everything thus far except the coolant tray.





Will re do it and open to any suggestions.


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## koenbro

Sand is an easy way to add some mass to the base. The top tube is empty, the bottom had already been filled.


----------



## koenbro

The coolant pump is quiet -- like that. Will have to rethink the trays though.


----------



## jwmelvin

Why don’t you like your trays?


----------



## addertooth

I went a different way with my table.  It is wider than the maximum X travel of the table.  This way, there is zero chance of anything accidently bumping the table in operation.  The wide stance will prevent rocking. The Mill is mounted on 3/8th steel plate, which is welded to the 2 inch square tubing with 1/8th wall.  They Y axis dimension is also generous, to ensure lots of move for oversized items with overhang in that axis as well.  As a note, I did not go CNC, nor will I. 

It is an 8 legged table with 8 adjustable feet for precise levelling.  Four of the legs are directly under the mill to reduce the chance of tube flex from occurring.  Flat panels could be added to the sides if any flexing is evidenced.


----------



## koenbro

@jwmelvin: Why don’t you like your trays?

I wanted them sloped towards the left (the drain) but the front one is not sloped enough. Now they are both spot welded in, so I cannot easily tilt it further. The second reason is that the dual drain system (needed because of the transverse support for the mill breaks the space up in two) seems overcomplicated.

Am tempted to yank out both trays and replace them with one 24x24" tray placed just below the top frame (ie. just below the crossmember that supports the front of the mill). Will see for now how this setup works.

Next phase will add the belows instead of the pathetic rubber sheet that PM delivers it with.


----------



## koenbro

addertooth said:


> I went a different way with my table.  It is wider than the maximum X travel of the table.  This way, there is zero chance of anything accidently bumping the table in operation.  The wide stance will prevent rocking. The Mill is mounted on 3/8th steel plate, which is welded to the 2 inch square tubing with 1/8th wall.  They Y axis dimension is also generous, to ensure lots of move for oversized items with overhang in that axis as well.  As a note, I did not go CNC, nor will I.
> 
> It is an 8 legged table with 8 adjustable feet for precise levelling.  Four of the legs are directly under the mill to reduce the chance of tube flex from occurring.  Flat panels could be added to the sides if any flexing is evidenced.



That looks great and promises to be stable. I am very constrained by space, and cannot afford a structure like that. My base's Y-axis is long enough to protect the motor in the front. I have built an enclosure that will partially protect the x-axis from bumps. Long material will stick out through the sides where I plan to place a curtain rather than a solid wall on the lower half.


----------



## koenbro

Two bellows to cover the ways. 


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----------



## rwm

koenbro said:


> Two bellows to cover the ways.


Ordering info?!
Robert


----------



## koenbro

McMaster Carr. 


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----------



## koenbro

Have run the system but the trays are leaking coolant. So have bought a granite countertop remnant from a local yard and will mount the mill onto it. 







Our plumber came by to do some other job do i asked him to put a drain hole. 

Can anyone suggest a spindle/router bit that can be used on granite? I am thinking of putting the slab on the CNC and finishing a countersink and maybe add some drainage grooves. 


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## 7milesup

Diamond bit utilized with water.  That is the only cutting edge that I know that will work with stone.


----------



## koenbro

Any examples of endmills for granite? Amazon search is mostly showing conventional cutters 


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## markba633csi

Good sized barrel cactus you have there- I have a couple nice ones myself but not quite that large
-M


----------



## macardoso

koenbro said:


> Any examples of endmills for granite? Amazon search is mostly showing conventional cutters
> 
> 
> Sent from my iPhone using Tapatalk Pro


I will add that I did try milling a slot with a small carbide endmill in granite a few years back. Got about an inch before there was a smooth nub where the endmill used to be. In all fairness, it did mill a slot at first. I'd stick to abrasive methods. Perhaps a diamond mounted point would work well if kept cool. 






						KBC,3/8X1/4 150G MOUNTED DIAMOND WHEEL 1/4SH,1-640-120,KBC Tools & Machinery
					

KBC,3/8X1/4 150G MOUNTED DIAMOND WHEEL 1/4SH,1-640-120,KBC Tools & Machinery




					www.kbctools.com


----------



## addertooth

Okay, I cannot resist this joke... please don't take it too personal (my fellow Arizonan).  If your tray is leaking, I know a good plumber 

If the slope is not enough, I would build up the inside surface with epoxy to create the slope you wish.  This is the easiest solution. 

Sometimes you re-engineer things, other times you correct the issue with the minimal fuss.  The choice is always yours.


----------



## Weldingrod1

Grinding work! You might look at diamond hole saws to get a smaller OD tool.

Yes, there are carbide bits that will cut stone. No, you cannot put them in a router.

You might ask a countertop shop if they can do what you want!

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## koenbro

I am a sucker for buying tools so I ordered the diamond bit recommended above. Have given up on the idea of carving drainage grooves though. So will just mount it and build up w epoxy if needed. 

UPDATE:  KBC tools is out of that diamond coated bit. So i cancelled the order. 


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----------



## GB21

koenbro said:


> Two bellows to cover the ways.
> 
> 
> Sent from my iPhone using Tapatalk Pro


This is next on my list for sure! This is my biggest gripe about the 728 besides the oil leak problem. I have been waiting for my superfly to grab ahold of that rubber flap.


----------



## jimrk

koenbro said:


> McMaster Carr.
> 
> 
> Sent from my iPhone using Tapatalk Pro


what part # for the Z?


----------



## koenbro

I used the same for both y and z. They both need to be cut to a narrower size. 


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----------



## jimrk

koenbro said:


> I used the same for both y and z. They both need to be cut to a narrower size.
> 
> 
> Sent from my iPhone using Tapatalk Pro


thanks


----------



## koenbro

Quick question: *how can I glue aluminum to granite, and make it water (ie coolant) proof*?

My setup works quite well, but the table leaks. The holes through the granite and the frame are 3/4", and the screw are 1/2". Even with rubber gaskets there is quite a leak. Then the 8020 frame on top the granite leaks despite using caulk applied quite generously inside and out.

SO I am rethinking the enclosure. I love. it that it keeps the chips contained but would like to run coolant. So decided to make a frame from 1.5 x 1.5 x 1/8" aluminum, TIG weld it so it's water proof in the corners, and hopefully it remains flat after welding. I want to attach it to teh granite and place the 8020 enclosure inside it.   So the angle frame becomes the water proof part. Something like this:






What solution do you recommend: caulk, glue, or what?

Otherwise that's what the enclosure looks on the granite slab (the sliding front doors are off for the photo):






As for the 4 holes through the frame, I will use two (on one diagonal) to attach the granite to the steel frame from below, and the other two (the other diagonal) to attach the mill to the granite from above. Have bought inserts from McMaster-Carr and have epoxied them in, such  that none of the holes is through the granite anymore.






Have used the center inserts, but bought two more styles as I wasn't sure what I really need.


----------



## Cletus

Consider using white 3M Fast-Cure 5200 Marine Sealant.   It does not let go and is used to set through-hull fittings on boats.   Make sure to use "fast-cure", else you'll be cussing for 8-days while it sets


----------



## koenbro

Cletus said:


> Consider using white 3M Fast-Cure 5200 Marine Sealant. It does not let go and is used to set through-hull fittings on boats. Make sure to use "fast-cure", else you'll be cussing for 8-days while it sets



Thanks, ordered. 


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----------



## koenbro

*4th axis*
Considering adding a 4th axis. The Acorn has room for the 4th, and I will just buy another Clearpath, but where do I even begin with the hardware? 

Would I just get a dividing head and mount the servo unto it? Please point me in the right direction.


----------



## jimrk

Depends on what your needs are  I used a rotary table and stepper on my mini mill.  Have not added one to my PM-728.


----------



## macardoso

koenbro said:


> *4th axis*
> Considering adding a 4th axis. The Acorn has room for the 4th, and I will just buy another Clearpath, but where do I even begin with the hardware?
> 
> Would I just get a dividing head and mount the servo unto it? Please point me in the right direction.


Here’s the issue with 4th axis units. Unlike getting ballscrews to replace lead screws for CNC, most rotary tables (worm gear) have pretty poor backlash that you can’t really get rid of. Also they have poor rigidity when unlocked since that really isn’t how they are designed to be used. That limits you to using them in an indexing fashion rather than being really great for full interpolated rotary motion. Or interpolated rotary with lots of backlash comp, and easy to machine materials


Alternate solutions include low backlash planetary gear heads (face mount) which is $$$ or harmonic drives $$$$. Both of which need to be fitted into custom enclosures. These have low enough backlash to be used for full rotary milling.

I have a big servo planetary gear head and a Yuasa super spacer body that I hope to put together to make a beefy rotary.







Just my personal opinions. I made a 4th axis from a Grizzly 4” rotary and it worked but was never accurate enough to do any real precision work.


----------



## Cletus

On my Mini-Mill CNC conversion (Mach3), I used a rotary table with a stepper motor and is turned out "decently accurate" and reliable for my purposes, very little backlash.   Now that I have the PM-935, I've built a stand-alone position driver (Arduino) for it and that works very nicely manually operated. It is small I admit, but it serves my purposes and see no reason why a larger rotary table cannot be adapted likewise.
Here it is on my Grizzly CNC Mini-Mill (Mach3 driven):






...and here it is setup for use, stand-alone on the PM935 (Arduino driven):


----------



## koenbro

Cletus said:


> On my Mini-Mill CNC conversion (Mach3), I used a rotary table [...]



Wow looks great in the video. The precision of those slots in the tube looks adequate for my skillset and expectations.

@Cletus and everyone else:  *What rotary table are you using or recommending*? Will an dividing head like the PM BS-0 work in this setting or are they incompatible?

I looked at the Grizzly 4" rotary that @macardoso mentioned and looks pretty good but if it is reasonable, would rather not get both a dividing head and a rotary. One advantage of the rotary though seems to be its lower height. Can't even figure out how much if any room is left in the z-axis once you mount a dividing head and turn it to point up.


----------



## jimrk

I used one from LittleMachineShop

https://littlemachineshop.com/products/product_view.php?ProductID=1810&category=


----------



## Cletus

Yes, those units from LMS lend themselves to CNC conversion nicely.


----------



## cxagent

Cletus said:


> Yes, those units from LMS lend themselves to CNC conversion nicely.


So those rotary tables have low enough backlash for CNC use? Or do they still need a lock function to prevent motion when the stepper motor is holding still?


----------



## Cletus

The one I have has very minimal backlash.


----------



## koenbro

As always, you guys are great -- thanks for the practical discussion.

I went ahead and ordered the LMS 4" precision rotary table that @jimrk linked to above. The reason I went with the LMS rotary over the PM BS-0 dividing head, as I initially intended, is the z height. The PM solution has the clear advantage of angular adjustment but am not convinced that with my z-axis limitations that's worth it. Also ordered the tailstock matching this table, and the 3-Jaw 3" lathe chuck. Have never used a lathe chuck (or a lathe  ) so I am very excited to try it/them out. Wanted to also get the compatible dividing plate set but they are out until late January.


Am very tempted by the elegant, self-contained and stand-alone solution @Cletus has shown above, because I think I can use it as a welding positioner as well. What motor and controller are you using, @Cletus ?


----------



## Cletus

For the standalone controller, I built my own using Arduino as the processor.  I can send you the Arduino code for it.  You will need to determine which size motor would best fit your particular table, probably a NEMA 17 or 23





__





						Arduino Rotary Table for Dummies
					

Ive had a few people tell me that they like the project (http://www.homemodelenginemachinist.com/showthread.php?t=25783) but dont feel comfortable with the electronics. Ive been playing around to simplify it down to where I feel anyone who wants to could comfortably build the controller. With...




					www.homemodelenginemachinist.com
				




For my TIG welding rotary table _(BTW my TIG welding talent is pretty atrocious)_, I bought this one on Amazon and did a few tweaks mainly beefing up the commutator arrangement for the work-clamp current flow, and replacing the speed potentiometer with a 10-turn pot for finer control


			https://www.amazon.com/gp/product/B07HF33C75/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
		










More stuff on it here:








						Cletus' Crossfire Build n Mods
					

Oh yes, he has good videos.  Also, I look at this and weep!




					forum.langmuirsystems.com


----------



## koenbro

Cletus said:


> For the standalone controller, I built my own using Arduino as the processor.  I can send you the Arduino code for it.  You will need to determine which size motor would best fit your particular table, probably a NEMA 17 or 23
> 
> 
> 
> 
> 
> __
> 
> 
> 
> 
> 
> Arduino Rotary Table for Dummies
> 
> 
> Ive had a few people tell me that they like the project (http://www.homemodelenginemachinist.com/showthread.php?t=25783) but dont feel comfortable with the electronics. Ive been playing around to simplify it down to where I feel anyone who wants to could comfortably build the controller. With...
> 
> 
> 
> 
> www.homemodelenginemachinist.com
> 
> 
> 
> 
> 
> For my TIG welding rotary table _(BTW my TIG welding talent is pretty atrocious)_, I bought this one on Amazon and did a few tweaks mainly beefing up the commutator arrangement for the work-clamp current flow, and replacing the speed potentiometer with a 10-turn pot for finer control
> 
> 
> https://www.amazon.com/gp/product/B07HF33C75/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
> 
> 
> 
> 
> More stuff on it here:
> 
> 
> 
> 
> 
> 
> 
> 
> Cletus' Crossfire Build n Mods
> 
> 
> Oh yes, he has good videos.  Also, I look at this and weep!
> 
> 
> 
> 
> forum.langmuirsystems.com


I have read your thread on the Langmuir forum and it is very impressive!  Setting the bar up high for the rest of us.


----------



## Cletus

Thanks for the compliment, much appreciated.


----------



## koenbro

Deos anyone know what is the thread size for the *drain* hole on the right side of the table? I thought I saw it mentioned in one of the threads, but searching does not retrieve it. I am very confused about pipe threads and sizes.


----------



## jimrk

'feels' like 1/4 NPT to me


----------



## Firebrick43

koenbro said:


> Deos anyone know what is the thread size for the *drain* hole on the right side of the table? I thought I saw it mentioned in one of the threads, but searching does not retrieve it? I am very confusing about pipe threads and sizes.


be careful.  Many non US machines actually use British tapered pipe threads. Japanese machines do, as do some Taiwanese.    The Germans do to although call it G1/8.  Any ways its has the same OD dimensions as NPT but is 19 threads per inch instead of 18.  So it screws in about 3 threads, you put a wrench on it and tighten, and end up damaging the threads.  Don't guess, get a threads per inch gauge and use it.


----------



## xr650rRider

koenbro said:


> Deos anyone know what is the thread size for the *drain* hole on the right side of the table? I thought I saw it mentioned in one of the threads, but searching does not retrieve it? I am very confusing about pipe threads and sizes.



Probably 3/8" NPT, other PM mills are.


----------



## koenbro

Firebrick43 said:


> be careful.  Many non US machines actually use British tapered pipe threads. Japanese machines do, as do some Taiwanese.    The Germans do to although call it G1/8.  Any ways its has the same OD dimensions as NPT but is 19 threads per inch instead of 18.  So it screws in about 3 threads, you put a wrench on it and tighten, and end up damaging the threads.  Don't guess, get a threads per inch gauge and use it.


Yeah, that is the most likely explanation. I got a brass 1/4" NPT and was able to thread it maybe two revs  before it got stuck. Have placed an order for a BSPT-threaded plastic elbow from McMaster -- will report back on the fit.


----------



## Cletus

Serviced and re-calibrated my CNC Mini-Mill today. Here’s the second pass making a bolt-circle in a test coupon (1/4" Drill)


----------



## ptrotter

Nice enclosure.


----------



## Cletus

Thanks!   ....yeah, I tend to get a little carried away


----------



## Tipton1965

Pretty cool.  Lots of chip clearing cycles.  With that thin of material and the flood coolant I'd drill those holes with a single plunge.


----------



## Cletus

Yup, me too normally. I did not put any effort at all into the gcode. Just ran a file from another project that used 0.5" stock I think.


----------



## koenbro

koenbro said:


> Yeah, that is the most likely explanation. I got a brass 1/4" NPT and was able to thread it maybe two revs  before it got stuck. Have placed an order for a BSPT-threaded plastic elbow from McMaster -- will report back on the fit.



It's official: the thread on the table is *BSPT*.

This is the item I ordered from McMaster and that fits well: Plastic Barbed Hose Fitting, 90 Degree Elbow Adapter, 10 mm Hose ID, 1/4 BSPT Male, catalog# 5218K341


----------



## koenbro

Cletus said:


> Serviced and re-calibrated my CNC Mini-Mill today. Here’s the second pass making a bolt-circle in a test coupon (1/4" Drill)


Love the enclosure. Mine is a 8020 frame that interferes with access to the sides and the back of the machine. Is yours suspended on pulleys?


----------



## Cletus

Yes, two very long drawer slides, pulleys, a Bimba pneumatic cylinder and solenoid valve.


----------



## Cletus

Hopefully this short video will make it a little clearer on what's going on with my Mini-Mill 4-Axis VMC setup (Apologies for the clutter in the shop today).
It's all mounted on a single, 2"x2" RHS vertical mast  (the lexan enclosure, Bimba cylinder, pulleys, drawer slides on both sides of the mast, monitor, Dell PC, keyboard, everything).  I've had this setup quite a few years now (since 2014, I believe) and no trouble with it at all. The coolant system consists of a small Rubbermaid cooler for the reservoir, a 12V RC fuel pump, and a SS kitchen strainer.  The Loc-line was modified with a small tube added inside that carries the fluid, while the Loc-line itself carries the air. A solenoid valve controls this air and a relay controls the pump via a PWM speed control. Mach3 controls AirBlast and Fluid, therefore this Line-loc coaxial arrangement can readily give me Flood (fluid only), Mist (coolant and air) or Air Blast only, all Mach3 controlled.  There was no plan really, I just started building and it just kept getting better and better as I mounted stuff on, LOL  (the mast was put there initially just to enable me to lift the mill onto the bench).

BTW I also have 115V power for the PC and monitor as well as three USB cables running through the mast, and luckily they all play nicely with no interference


----------



## koenbro

Very helpful @Cletus. Such a practical, clean, and ingenious solution.

I am still sorting out the best way to recirculate the coolant. It is really messy and frankly wish I could do without. However I do NOT intend to inhale atomized/sprayed coolant so sprayed coolant is out for me. I saw somewhere on YT (maybe on Stefan Gotteswinter's channel) that pulses of air with isopropyl alcohol mixed in clear the chips and cool aluminum. I think that might be least toxic solution in the home shop although ingested IPA (and inhaled is no different really) can be toxic also.

I had a sink drain mounted on mine that just broke as I manhandled the plastic lower bits. Plus the 1/16" lip prevented a complete drainage of hte fluid. So I am 3D printing something that will be the next version.

I also have a few additional parts on order: a Priest tools air power draw bar, and a Teknic z-axis brake. ONce instaleld with the new coolant drainage solution will make a walk through video of my setup.


----------



## pmistry

Good morning All!
I trust this finds you all safe and keeping well?

Thank you for this wonderful build post and all the insightful advice as I too just received my PM-728V-T this past weekend and would like to convert it eventually to CNC.  I also received the PM-1130 lathe which I will convert to CNC at a later time as well.  If I may trouble those of you who have built enclosures for your PM-728's; what are the dimensions of your enclosures and the clearances you have allowed for on each side, front and back from the machine?

I'd like to construct the base(pan) first and then mount the machine on it.


----------



## jimrk

koenbro said:


> It's official: the thread on the table is *BSPT*.
> 
> This is the item I ordered from McMaster and that fits well: Plastic Barbed Hose Fitting, 90 Degree Elbow Adapter, 10 mm Hose ID, 1/4 BSPT Male, catalog# 5218K341


Thanks


----------



## koenbro

pmistry said:


> Good morning All!
> I trust this finds you all safe and keeping well?
> 
> Thank you for this wonderful build post and all the insightful advice as I too just received my PM-728V-T this past weekend and would like to convert it eventually to CNC. I also received the PM-1130 lathe which I will convert to CNC at a later time as well. If I may trouble those of you who have built enclosures for your PM-728's; what are the dimensions of your enclosures and the clearances you have allowed for on each side, front and back from the machine?
> 
> I'd like to construct the base(pan) first and then mount the machine on it.



Mine is 48” wide x 31” deep x 27” high. There are photos of it earlier in this thread. 


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## koenbro

Have installed yesterday the rapid tool changer from Priest. Works well, ave to figure out how to stop air leaks.


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----------



## koenbro

Also have broken down and bought the Teknic x-axis brake. After some fumbling because noob, it was easy to wire into Acorn and works very well. My concerns about weights with a pulley or the air cylinder is that they will not precisely keep the z position. With the brake if I press cancel or e-stop the system keeps z. 







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----------



## adamyq

I have been following this for a while and bugging koenbro via PMs, he suggested we move it to the main board.

I have duplicated the teknic order to include the brake (and forgotten AC powder cord). Doesn’t appear prices have moved at all. I share koenbro’s philosphy of buy once cry once, so I went with all the upgraded motors and e-brake.


----------



## adamyq

I just got my PM728 into the shop and started teardown for the ball screw install (I assume you swap them in order of Z-Y-X). My current questions:

1. Does the e-brake require an additional coupler? I haven’t ordered the McMaster items previously linked yet. 

2. I know the 728 has 12mm slots, and I have a Kurt DX6 vise. I need to snag some keys, but they only list 1/2” standard keys. I assume they’ll fit/work, but figured I would ask.


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## koenbro

adamyq said:


> 1. Does the e-brake require an additional coupler? I haven’t ordered the McMaster items previously linked yet.
> 
> 2. I know the 728 has 12mm slots, and I have a Kurt DX6 vise. I need to snag some keys, but they only list 1/2” standard keys. I assume they’ll fit/work, but figured I would ask.


Thank you @adamyq for your messages and agreeing to transfer here. 

You do *NOT* need an extra coupler for the Teknic brake. To clarify, you already need one coupler to connect the servo motor and the ball screw, so you do not need a _second_ coupler. The brake has a both a female end into which connects the z servo motor, and a male end that mates with the Z-axis screw via the one coupler you need. The female end of the brake has a built in coupler-like tightening mechanism to attach the 1/2" motor shaft. The brake's housing has a hole/tunnel and you rotate the brake shaft until you can reach the built-in coupler's screw with an allen wrench.
As I posted earlier in this thread, the coupler provided by PM is metric so it attaches to the ballscrew, but then you have to provide your own replacement end to attach the inch motor shafts (3/8" x2 and 1/2"). I got them from McMaster Carr ( 2401K14 and 2401K15 ) and were pricey ($130 for the three). You reuse the spider from PM.

As for the 1/2" keys for the vise, I do *NOT* think they will work in the 12mm slots. If someone knows otherwise please chime in because I am also interested in mounting keys for my DX4 vise.


----------



## koenbro

@adamyq , you mentioned that you will use a Masso controller. I am not familiar so looked it up; this looks fantastic!!






I might have gone with this solution had I known about it at the time. It is so nice to know that amateurs like us have access to high-performing controllers.


Will follow with great interest your build to see how you integrate probes, limit sensors and touch off devices. I found them to be invaluable and love the KP-3 probe, MPG and limits.


----------



## adamyq

[mention]koenbro [/mention] I think I am actually going to chicken out of the mass for the time being and mimic your acorn setup, main reason being I like the wireless pendant option better. I’m simultaneously building an airplane and often need to manually mill some brackets or special tooling. Also very interested if you can essentially control the system like a power feed for refacing surfaces.

Full disclosure, I started going down all sorts of rabbitholes because of this thread (4th axis, pneumatic tool changer, touch probes, etc), but I’ve forced myself to dial back and really focus on getting it back to being a functional semi-manual (mpg) mill. 

Maybe someday I’ll get me up going the Masso route…the benefit of the acorn is that it’s very inexpensive and there is a cult following that May be interested in resale of components.


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----------



## adamyq

koenbro said:


> As for the 1/2" keys for the vise, I do *NOT* think they will work in the 12mm slots. If someone knows otherwise please chime in because I am also interested in mounting keys for my DX4 vise.



I know the PM clamp kit acknowledges that it’s a 1/2” kit but says it will work on the 12mm slots. I may just order the 1/2” and, you know, mill them down to 12mm.


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----------



## adamyq

Ok, just spent 2 hours disassembling and reassembling with the ultra precision cnc screw kit. As koenbro said, the drawing is fairly sufficient, though I had to stare at the y axis screw covers for a minute because I didn’t pay attention to their orientation when I pulled the Y off.

I was pretty proud of myself….until cleaning up I discovered the dreaded bag of extra parts. Looks like 3 grease fittings, and I’m betting they go on the double bearings somewhere.

Hard to tell if I got the gibs reinstalled correctly (again they fell out before I could note orientation). I put the smoother sides against the dovetails, which would make sense.

Other thing worth noting was the same comment made early about the bearing nuts. Having read that, I played around a bit and see how one could easily end up with backlash. I’ll have to make a spanner to properly tighten them, but good enough for now. 

Thanks to everything who provided comments and feedback, it made this step of the conversion much easier.


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----------



## pmistry

koenbro said:


> As for the 1/2" keys for the vise, I do *NOT* think they will work in the 12mm slots. If someone knows otherwise please chime in because I am also interested in mounting keys for my DX4 vise.


Good afternoon Fellas.
I can confirm the 1/2" keys if truly 1/2" in measure will not fit in the slots of the table.  I had to purchase a metric clamping set. Here's a picture of what I purchased and it barely fits as the tolerances were very tight.


----------



## koenbro

adamyq said:


> [...] I’ll have to make a spanner to properly tighten them, but good enough for now.




This is the spanner I used for the precision nuts on the axes:

6975A12


----------



## koenbro

adamyq said:


> [mention]koenbro [/mention] I think I am actually going to chicken out of the mass for the time being and mimic your acorn setup, main reason being I like the wireless pendant option better. I’m simultaneously building an airplane and often need to manually mill some brackets or special tooling. Also very interested if you can essentially control the system like a power feed for refacing surfaces.



For reference, this is my Acorn setup. Also got their eStop which is high quality, and added a link to the power draw bar.

itempart #cost​Acorn CNC controller kit$ 329​Acorn Mill "Pro" CNC Software license14457​$ 159​WMPG-4 Wireless MPG CNC control pendant$ 299​KP-3 kit for use with Acorn14946​$ 699​C86ACCP board$48​*TOTAL*$ 1,534​Estop Button with 2 contact closures14534​$ 45​Priest Drawbar PM 728 VT$ 799​
I do NOT recommend the PM 0-10V spindle control board. I have it and it does not allow fine tuning. Get instead a KBSI-240D Signal Isolation Board 115/230v-ac 0-10v-dc.

The MPG and the KP-3 probe are invaluable. I did not know anything about Acorn before the conversion, but I understand now why they have such a loyal following: the system is good value and integrates very well.

And yes you can use the mill like a manual with power feed using the MPG.


----------



## adamyq

koenbro said:


> This is the spanner I used for the precision nuts on the axes:
> 
> 6975A12



Added that with the couplers. Anything else I should tack on to my McMaster order?


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## koenbro

Shims to level the machine and correct the nod:    97235K816
Loctite 638. 

Not necessary just nice to have: Bellows  1320K111


At some point a precision reference ring, but we can talk later when tooling comes into the conversation. As a preview, I do not recommend R8, get TTS instead. Then some TTS compatible touch off indicator and this: 2266A76


----------



## adamyq

koenbro said:


> Shims to level the machine and correct the nod: 97235K816
> Loctite 638.
> 
> Not necessary just nice to have: Bellows 1320K111
> 
> 
> At some point a precision reference ring, but we can talk later when tooling comes into the conversation. As a preview, I do not recommend R8, get TTS instead. Then some TTS compatible touch off indicator and this: 2266A76



Are these for the stand feet?


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## koenbro

adamyq said:


> Are these for the stand feet?
> 
> 
> Sent from my iPhone using Tapatalk


Shims are mostly for the nod. I also used them for leveling the granite slab on the metal stand, but that will not apply to you -- althought this begs the question: What are you going to mount the mill? Are you planning an enclosure, and will you use coolant?

Also, I am sure you recognize, but I feel better stating the obvious again: I am very much a noob who has never seen a mill before starting this project, much less used one. There are on this forum ppl with decades of experience, and I don't want to sound like I have the answers, cause I don't. I had tons of fun making this conversion and learned A LOT, and the end result is decent for a home gamer, that's all.


----------



## adamyq

I’ve got a weird workshop setup for the moment with the airplane build, so I have to be able to move everything around. I got the PM base and built riser on a mobile base (similar setup on my previous mill). I’d clamp it to some channel on the wall for stability, but could unclamp it and move it as needed if I have to work on a longer component (horizontal stabilizer or wing). 

I obviously haven’t trammed or even mic’d the table yet.

Circling back to an earlier question - do those grease fittings in fact go directly on the double bearings?


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## koenbro

adamyq said:


> Circling back to an earlier question - do those grease fittings in fact go directly on the double bearings?



Don't remember, and not sure what a grease fitting is. Can you pls look at the PM instruction sheet and tell me what item number is that?


----------



## adamyq

koenbro said:


> Don't remember, and not sure what a grease fitting is. Can you pls look at the PM instruction sheet and tell me what item number is that?



They don’t appear anywhere on the drawing but they definitely exist.







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## adamyq

adamyq said:


> They don’t appear anywhere on the drawing but they definitely exist.
> 
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk



Update: I removed the Z axis to check out the bearing assembly, it does appear that there is a threaded area where the grease fitting will go, but there’s a set screw That came installed with the bearing assembly.












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## koenbro

Mine looked different. I might have an earlier version and don’t recall adding the zerks. Also don’t think they were preinstalled. Finally I don’t think you can access them once installed. For example, neither the z- nor the y-axis double nuts are accessible once installed. The x-axis nut is accessible if removing the motor and the opposite end connection. Lots of work.


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## adamyq

koenbro said:


> Mine looked different. I might have an earlier version and don’t recall adding the zerks. Also don’t think they were preinstalled. Finally I don’t think you can access them once installed. For example, neither the z- nor the y-axis double nuts are accessible once installed. The x-axis nut is accessible if removing the motor and the opposite end connection. Lots of work.
> 
> 
> Sent from my iPhone using Tapatalk Pro



I think you could get to the Z axis through the side cover plate assuming you run the head all the way up, but the other two wouldn’t indeed be a pain in the ass. Maybe it’s just for initial greasing, but you’d think they’d give you better instructions.

Anyway, I place the order for the motors and controller hardware today, hopefully I have something to play with next weekend.


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## adamyq

> [TR]
> [TD]C86ACCP board[/TD]
> 
> [TD]Priest Drawbar PM 728 VT[/TD]
> 
> I do NOT recommend the PM 0-10V spindle control board. I have it and it does not allow fine tuning. Get instead a KBSI-240D Signal Isolation Board 115/230v-ac 0-10v-dc.



Questions on these.

1. I just noticed you have an extra board specifically for the clearpaths. Does this just simplify integration?

2. Did you do the priest drawbar or drawbar max? Having watched a number of YouTube videos where people have these, it’ll no doubt be the first upgrade.

3. The eBay link to the speed controller you like seems broken.


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## koenbro

adamyq said:


> Questions on these.
> 
> 1. I just noticed you have an extra board specifically for the clearpaths. Does this just simplify integration?
> 
> 2. Did you do the priest drawbar or drawbar max? Having watched a number of YouTube videos where people have these, it’ll no doubt be the first upgrade.
> 
> 3. The eBay link to the speed controller you like seems broken.
> 
> 
> Sent from my iPhone using Tapatalk


#1 Yes the C86ACCP is important. The minor reason is that you can plug the Clearpath molex connectors easily. The main reason is that the C86ACCP mediates important functions of hardware control and e-stop/ OK signaling. Fellow Phoenician Marty (@martyscncgarage on Youtube) has what I regard as the definitive video showing the wiring  of the C86ACCP for the Clearpath. I used it and will look for  it if you want.

#2 The plain PDB is sufficient. 

#3 Sorry might point to the item I bought. Just search eBay for KBSI 240D signal isolator.


----------



## adamyq

koenbro said:


> Mine looked different. I might have an earlier version and don’t recall adding the zerks. Also don’t think they were preinstalled. Finally I don’t think you can access them once installed. For example, neither the z- nor the y-axis double nuts are accessible once installed. The x-axis nut is accessible if removing the motor and the opposite end connection. Lots of work.
> 
> 
> Sent from my iPhone using Tapatalk Pro



Just talked to PM, guy was as confused as me. I did remove the set screw, installed the zerk and ran some grease in one. Not sure if I’ll leave the zerk in for reassembly or put the set screw back in since they aren’t exactly accessible. I just can’t tell if that set screw holds anything.


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## adamyq

koenbro said:


> #1 Yes the C86ACCP is important. The minor reason is that you can plug the Clearpath molex connectors easily. The main reason is that the C86ACCP mediates important functions of hardware control and e-stop/ OK signaling. Fellow Phoenician Marty (@martyscncgarage on Youtube) has what I regard as the definitive video showing the wiring of the C86ACCP for the Clearpath. I used it and will look for it if you want.



I just checked out some of Marty’s videos, looks like a logical upgrade. I’m back to waffling between the acorn and that Masso. I’ll be traveling for a few days so plenty of time to research. 


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## adamyq

koenbro said:


> #2 The plain PDB is sufficient.



I might’ve missed this in an earlier post, which quick change collets did you go with?  I was looking at the Tormach but there seem to be two types:  set screw and the ER20 style.  


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## koenbro

I have both. The set screw works for endmills, but ER20 is needed for drills and touch off probe.


----------



## pmistry

koenbro said:


> I do NOT recommend the PM 0-10V spindle control board. I have it and it does not allow fine tuning. Get instead a KBSI-240D Signal Isolation Board 115/230v-ac 0-10v-dc.


Thank you for this.  I was about to order this board from PM for my conversion.   I'll try to locate a KBSI-240D myself.  Much appreciated @koenbro


----------



## adamyq

koenbro said:


> I have both. The set screw works for endmills, but ER20 is needed for drills and touch off probe.



Looks like the set screws are available on 4 sizes, but not sure I understand the difference between a 3/8” set screw and a 3/8” ER20 collet.  Obviously going the ER20 route for common end mills is more expensive vs set screw.  Is the ER20 more flexible (drill bit tolerances), or does it provide improved concentricity?


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## koenbro

End mills have a flat machined onto their shaft. That is where the set screw connects. 3/8" or 1/2", etc are the shaft diameters. YOu need to decide what cutters you need first, then get an assortment of holders for them. Our mills don't have enough power, so I think 1/2" is max for Alu, and 3/8" for steel IMO. I also have some 1/4". I started with the basic PM endmill kit, and now I use more upgraded stuff from Travers, McMaster etc.

Some tools do not have the machined flat so you use ER collets for them, again matched for their dia (drills, reamers, Noga indicator holder, probes, fall into this category)

To your earlier question:  the KP-3 probe has a 1/2" shaft so I use a 1/2" ER collet. An alternative btw is the Haimer, but I have never used that, so no opinion; however, I love the KP-3.

IMO it is important to not just buy the CHEAP!!!!  SCORE!!!   collets from Amazon or Ebay, as they might have runoffs and other problems. I got stuff made in Japan from McMaster. One ends up with a collection, for example, I use a 5.1mm (.201") drill for the 1/4" holes that are my standard, so I got a matched collet; collets generally cover a very narrow range.


----------



## ptrotter

Tormach has TTS Gauge Holders that are lower profile than Endmill Holders that work well for holding gauges and probes.  I use them on my KP-3 and Haimer.  Most 1/4" endmills do not have flats on them so a collet holder is probably best for those.  Collets "should" have better concentricity that endmill holders since you are pressing the endmill to one side in an endmill holder with the set screw, but I'm not sure it will make much difference in reality.


----------



## koenbro

ptrotter said:


> Most 1/4" endmills do not have flats on them so a collet holder is probably best for those.


Yes, I stand corrected. Although I have some 1/4" endmills, their shank is 3/8" with flats.







And here are my collets:


----------



## adamyq

koenbro said:


> Mine looked different. I might have an earlier version and don’t recall adding the zerks. Also don’t think they were preinstalled. Finally I don’t think you can access them once installed. For example, neither the z- nor the y-axis double nuts are accessible once installed. The x-axis nut is accessible if removing the motor and the opposite end connection. Lots of work.
> 
> 
> Sent from my iPhone using Tapatalk Pro



What trick did you use for tightening the bearing lock nut? I’ve had good success on X and z by applying pressure to the threaded side bearing and even just finger tightening (waiting for spanner to arrive).

I’m struggling on the Y, it’s like the the shank is a bit longer that the bearings in the housing so the nut bottoms out. I can’t tell for sure, will disassemble tomorrow and see.


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## adamyq

koenbro said:


> There was no easy way to attach the sensors to the casting; tried to drill a hole, but I learned very quickly that that's not going to work. So I decided to reuse the tapped holes for the locking levers on the saddle. I designed a simple bracket in Fusion.
> View attachment 356606
> 
> 
> Then cut in on the router out of scrap 1/16" 6061.
> View attachment 356608
> 
> 
> 
> Here it is mounted on the mill. The left sided sensor is already on; have added the second (+ limit ) sensor since.
> View attachment 356609
> 
> 
> 
> I plan to add two sensors for axis Y and maybe one for axis Z (upper limit). Still haven't figured out how and where I mount the y-axis sensors, as I want to use existing holes in the casting.
> 
> More importantly, will need to figure out how to configure the Acorn to stop the motors. Right now, it shows on the screen that the sensor is activated, but the motors do not stop.



Did you ever sort out why the sensor would activate but not stop the system?

I’m debating if I want to add these at all. There will be plenty of times I walk away from the machine. 


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## koenbro

adamyq said:


> What trick did you use for tightening the bearing lock nut? I’ve had good success on X and z by applying pressure to the threaded side bearing and even just finger tightening (waiting for spanner to arrive).
> 
> I’m struggling on the Y, it’s like the the shank is a bit longer that the bearings in the housing so the nut bottoms out. I can’t tell for sure, will disassemble tomorrow and see.
> 
> 
> Sent from my iPhone using Tapatalk


Please post photos, as I do not understand the shank length leading to bottoming out. I can post photos too if you need them.   

If it's about item #6 in the PM drawing, the precision locknut, I use a Knipex Cobra before the spanner arrived.


----------



## koenbro

adamyq said:


> Did you ever sort out why the sensor would activate but not stop the system?
> 
> I’m debating if I want to add these at all. There will be plenty of times I walk away from the machine.
> 
> 
> Sent from my iPhone using Tapatalk


Yes, the limit sensors worked out in the end and I could not imagine the system without them. Happy to post screen shots of the Acorn wizard. My first experience with CNC is with the AVID CNCPRO system assembled from a kit, that comes with 5 inputs (2 per axis, except axis-z not having a minus limit; due to the slaved dual y, there are 4 sensors on y, 2 for x, and one for z).

Because of this, I thought I will need plus and minus sensors, but Acorn allows settings software limits. So my current setting is x minus, y minus, and z plus, all normally closed (safer than the normally open sensors AVID offers, but also quite a bit more expensive); the matching x plus and y plus are set in software. I also have a soft z minus limit that is not practically useful. When I turn on the system, it homes first to the sensors, then machine coordinates are set,  and the soft limits control the range of motion. Seems very safe.

Check out what I wrote earlier about NC sensors.


----------



## ptrotter

On my Acorn setup I put in X+ and Y+ limit switches as well as soft limits so that in normal cases the soft limit is hit before the switches. I did this because sometimes I want to move my home switches to reduce the work envelope so that homing is quicker. I believe the soft limits are set as a distance from home so if I move the home switch inward, the soft limit would be too far.  The limit swich will protect me then.


----------



## koenbro

ptrotter said:


> On my Acorn setup I put in X+ and Y+ limit switches as well as soft limits so that in normal cases the soft limit is hit before the switches. I did this because sometimes I want to move my home switches to reduce the work envelope so that homing is quicker. I believe the soft limits are set as a distance from home so if I move the home switch inward, the soft limit would be too far.  The limit swich will protect me then.



That's a cool way to do it, in particular when considering that homing z and x is so slow that it takes minutes.


----------



## adamyq

Status update:

Got the X and Y motors installed, and movement. Still not properly configured (I.e. 1 inch in y command results in 2 inch movement), but I assume easily remedied when I get into the configuration. Note that I just connected my two CP servos to the 8P connector. I had seen several folks cut the cables and splice but didn’t understand why. That said, there may be a good reason.


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## adamyq

Questions on the Z axis:

1. The cast housing is pretty dang tall, so I could maybe get ~60% engagement on each axis. Note that this is the eBrake shaft. See photo.

2. The flange holes on the brake are just a shade too small for the screws that come with the cast mount. Did anyone else have this issue? I’m talking like ~5.5mm jokes vs the 6mm hex caps. Easy enough to bore out, but figured I’d ask.








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## koenbro

adamyq said:


> Questions on the Z axis:
> 
> 1. The cast housing is pretty dang tall, so I could maybe get ~60% engagement on each axis. Note that this is the eBrake shaft. See photo.
> 
> 2. The flange holes on the brake are just a shade too small for the screws that come with the cast mount. Did anyone else have this issue? I’m talking like ~5.5mm jokes vs the 6mm hex caps. Easy enough to bore out, but figured I’d ask.
> 
> 
> 
> 
> 
> 
> 
> Sent from my iPhone using Tapatalk



Yes and yes. Engagement is about 50-60% and the flange holes need to be drilled out. 


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## rwm

Could you not machine the casting down shorter? I am surprised to see a Lovejoy coupling rather than a flex disc coupling? More slop in the Lovejoy.


----------



## Firebrick43

rwm said:


> Could you not machine the casting down shorter? I am surprised to see a Lovejoy coupling rather than a flex disc coupling? More slop in the Lovejoy.


I haven't seen a disc type coupling on a CNC machine newer than the early 90's???   Even bellows are not used as much any more.  Alot of couplings are now the Rotex style, which are very similar to lovejoys.  It depends on the accuracy and the durometer of the spider.


----------



## rwm

You are probably right Firebrick. Hey there is a good discussion of couplers in this thread that shows the various types:








						CNC PM-728V-T
					

I have completed the first phase of my CNC  conversion. I had a couple questions in another thread, but didn’t receive any feedback so I started a new thread to hopefully get a few answers and some feedback.  First, a little bit about my setup. It’s a pm-728vt with PM’s CNC kit. G540 running...




					www.hobby-machinist.com


----------



## adamyq

koenbro said:


> There was no easy way to attach the sensors to the casting; tried to drill a hole, but I learned very quickly that that's not going to work. So I decided to reuse the tapped holes for the locking levers on the saddle. I designed a simple bracket in Fusion.
> View attachment 356606
> 
> 
> Then cut in on the router out of scrap 1/16" 6061.
> View attachment 356608
> 
> 
> 
> Here it is mounted on the mill. The left sided sensor is already on; have added the second (+ limit ) sensor since.
> View attachment 356609
> 
> 
> 
> I plan to add two sensors for axis Y and maybe one for axis Z (upper limit). Still haven't figured out how and where I mount the y-axis sensors, as I want to use existing holes in the casting.
> 
> More importantly, will need to figure out how to configure the Acorn to stop the motors. Right now, it shows on the screen that the sensor is activated, but the motors do not stop.



I’m on to this phase now. Did you make those black sensor clamps or find them somewhere? Also curious on the cable you used.

I’ll likely mimic your x mounting strategy. Did you come up with a y solution?


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## koenbro

adamyq said:


> I’m on to this phase now. Did you make those black sensor clamps or find them somewhere? Also curious on the cable you used.
> 
> I’ll likely mimic your x mounting strategy. Did you come up with a y solution?



I changed the mounts and am using 3D printed ones. They better match the movement range in x minus. This is the x minus:






And it has an Aluminum block mounted on the saddle (?):






The reason I gave it an overhang is that chips flying have stuck to the sensor and tripped it on the previous iteration.

This is Z:





	

		
			
		

		
	
It It gets tripped by an 8020 angle connector.

And this is y. It is the most primitive but works:


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## adamyq

Wow, those look great. I’ll likely try and replicate your setup to leverage your trial and error. Would you mind sharing the files for the printed parts?

I’ve been debating the Y-, what drove your decision there?  I’m likely going with the same sensors (thanks again), where did you source the 90 deg connector cables?

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## koenbro

The choice of placing the y at minus had to do with the convenience of attaching the sensor; more tricky to mount at Y-plus.

The cables came from Automation Direct. A word of caution: depending of where you place your control box, you might need longer cables.

Happy to share the 3D print files, but not sure how to upload the *.obj mesh files here. I have sent a DM with the link.

These are the renders should anyone care:


----------



## adamyq

koenbro said:


> Not sure how to upload the mesh files here. I have sent a DM with the link.



They look simple enough, no worries. What issue did you have on the X-? It looked like your old plate setup was legit, though this setup looks more like what I was considering.


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## adamyq

Probably going to go with the sensors and cables below (for others following):



			https://www.automationdirect.com/adc/shopping/catalog/sensors_-z-_encoders/inductive_proximity_sensors/12mm_round_industrial_automation/triple_sensing_(12mm)/dw-as-502-m12
		




			https://www.automationdirect.com/adc/shopping/catalog/cables/sensors_-z-_switches/pico_(m8)_normal_duty_q-z-d_cables/5-pole_pico_(m8)_cables/7000-08951-6950150
		



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## koenbro

Our messages must have crossed; check my last prior message (#240) and check your DM inbox.

Yes, I used the DW-AS-502-M12 sensor, but the cable you link is too short IMO; of course it depends on where the control box is placed. For me 2m was barely enough, I got two longer ones.

As for the previous design, it placed the sensor on the saddle in a fixed location, making it harder to fine tune the limits of movement. The current version allows it to slide on the table. The second problem was that the sensor was facing up and chips were landing on it, and it got triggered a few times. The current design prevents that.


----------



## adamyq

Is anyone running compressed air instead of a full on liquid lube/cooling system? I’ve had good success with the old wd40 on my previous mill, but I’ve been debating an air jet to blow chips away from the cutting, and discovered the fogbuster system as well. I may add a full on cooling system in the future, but looking for input on air options for now.


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## Cletus

I am using this "el cheapo" unit from Amazon and very happy with it (if it ever breaks, cheap enough to just buy another).  I also have a yellow "coil hose" with a little hand nozzle hooked to the table for manual chip blowing. My 16gal ShopVac is the main beast for chip cleanup of course.  On the CNC Mini Mill I'm running full flood coolant. For that I'm using a 12v RC fuel pump to run coolant from a reservoir to the Loc-Line nozzle, this has worked flawlessly for the last 9-years.



			Amazon.com


----------



## adamyq

I had bought a similar amazon nozzle but like the mist option, may snag that one. Thanks!


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## koenbro

I am really torn about this. I have both, and the flood is very messy. Although the  system is contained, and essentially leak free, it is still messy. So I reserve it for steel. 
Stefan Gotteswinter mentioned in one of his videos that isopropyl alcohol helps give a great finish to aluminum, in addition to cooling. I have the Noga MC 17001 Mini Cool single nozzle system. My concern with the mist system is that one, you end up inhaling the product, and second, you have a potentially flammable vapor. Not sure if justified, but these concerns hold me back. Using the system with air alone is fine.


----------



## Cletus

The Isopropyl Alcohol mist is a flash fire waiting to happen, I stayed away from that route, although I did try it at first and it worked quite well. Not worth the risk.  BTW Alcohol burns with an invisible flame, so BEWARE!


----------



## rwm

Cletus said:


> The Isopropyl Alcohol mist is a flash fire waiting to happen, I stayed away from that route, although I did try it at first and it worked quite well. Not worth the risk.  BTW Alcohol burns with an invisible flame, so BEWARE!


Ask Ricky Bobby about that.


----------



## koenbro

rwm said:


> Ask Ricky Bobby about that.









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## GB21

I just replaced my 3d printed proximity sensor mounts with aluminum. Anytime I would rehome for whatever reason I would have to re-zero the part sometimes it would be off by 5 or 6 thou. I knew it wasn't right because my router has the same setup and is repeatable to like a tenth. The issue has this disappeared with the aluminum mounts. I'm not sure if it was vibration or movement of the wires tugging them around. Something to think about.


----------



## koenbro

GB21 said:


> I just replaced my 3d printed proximity sensor mounts with aluminum. Anytime I would rehome for whatever reason I would have to re-zero the part sometimes it would be off by 5 or 6 thou. I knew it wasn't right because my router has the same setup and is repeatable to like a tenth. The issue has this disappeared with the aluminum mounts. I'm not sure if it was vibration or movement of the wires tugging them around. Something to think about.




I am very new to 3-D printing and I’m still learning about different materials. My current mounts are made out of ABS but would love to see the aluminium ones. Will you be able to post some photos?


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----------



## GB21

X axis mount





X axis with cover.
r
	

		
			
		

		
	






Y axis mount. 
Pretty basic. 




Janky printed cover, somehow "temporary" things like to stick around for a while. Currently running parts so chips everywhere.







Z axis still needs replaced but its next on the list when I get time.


----------



## koenbro

@GB21  That looks great -- special thanks for the video. I might replace the ABS one with Alu, but first will check the repeatability you mentioned.

That said, most impressed with the toolchanger!






Would you pls share details: what controller are you using: Acorn, or some other? How did you program it?

My next step will be an ATC and expect it will be very difficult. Thanks in advance.


----------



## koenbro

@adamyq asked about my config settings in the Acorn Wizard. Happy to share them here, and if anyone can see something that can be improved pls let me know.


----------



## koenbro

AXIS setup:


----------



## koenbro

SPINDLE:






TOUCH:


----------



## koenbro

PERIPHERAL:











PREFERENCES


----------



## koenbro

I realize now the Clearpath config may matter also -- @adamyq mentioned he gets an exaggerated movement to commands. Will try to get those screenshots as well soon.


----------



## adamyq

Thanks!  I plan to dive into some more troubleshooting tomorrow. Made and ran the first CNC program today using the bench test config (and a scrap piece of plywood).  Pretty exciting to be getting close.

Do you use your NPN sensors as both home and limit? I am starting to think about how to wire up my newly-acquired NPN sensors (same ones you have), but your inputs only show three of them.  Probably a noob question, but does the machine just automatically jog in a certain direction until it hits one, and thus you have the X in series?


----------



## koenbro

adamyq said:


> Do you use your NPN sensors as both home and limit? I am starting to think about how to wire up my newly-acquired NPN sensors (same ones you have), but your inputs only show three of them.  Probably a noob question, but does the machine just automatically jog in a certain direction until it hits one, and thus you have the X in series?



Yes, I use them for both and thus the minimum setup is one sensor per axis. You specify the direction, and then the machine will know where (in which direction) to find the sensor -- see Axis > Homing screens above.  When you turn it on, the first Cycle Start will home the machine,  ie. move towards that sensor; then the machine coordinates will be set to (0,0,0).

The opposite limit is set in software -- see my screenshots above.

Of note, I DO NOT have them in series, although some configurations for Acorn are doing it that way.


----------



## GB21

koenbro said:


> @GB21  That looks great -- special thanks for the video. I might replace the ABS one with Alu, but first will check the repeatability you mentioned.
> 
> That said, most impressed with the toolchanger!
> 
> 
> 
> Would you pls share details: what controller are you using: Acorn, or some other? How did you program it?
> 
> My next step will be an ATC and expect it will be very difficult. Thanks in advance.


Yes I am using the acorn with swissi's probeapp over on the centroid forum.  https://centroidcncforum.com/viewtopic.php?f=60&t=6149&sid=0d45b3d3b0d6c1417d13925c36c32000
Even though its a "simple" atc It took about 2-3 days of cad work to design and another FULL week of work to move the motor controller box off the head of the mill, machine all the parts, wire everything and plumb the pneumatics. I am currently reading and trying to learn how to write/edit custom macros and plc programming so someday I can make carousel atc. Its a lot of work but its worth it when I can walk away from the mill and do other things while its running.


----------



## adamyq

I’m still having a really strange issue with my setup. I went and copied all of the settings verbatim from koenbro’s screenshots, but the issue remains. In short, I tell it to jog 0.100” on any axis, and it goes 0.800”. I went and double checked all of the model numbers of my motor to make sure there’s not something mismatched were pulses/Rev is off, but no dice. 

Obviously I can override it by changing the lead ratio or the steps per revolution, but it feels like something has to be off somewhere else. For reference, I am running:

Acorn
C86ACCP board
2 x CPM-SDSK-2321S-ELS (X&Y)
1 x CPM-SDSK-3421S-ELS (Z)

Any thoughts are welcome. 


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## LucidCnC

adamyq said:


> I’m still having a really strange issue with my setup. I went and copied all of the settings verbatim from koenbro’s screenshots, but the issue remains. In short, I tell it to jog 0.100” on any axis, and it goes 0.800”. I went and double checked all of the model numbers of my motor to make sure there’s not something mismatched were pulses/Rev is off, but no dice.
> 
> Obviously I can override it by changing the lead ratio or the steps per revolution, but it feels like something has to be off somewhere else. For reference, I am running:
> 
> Acorn
> C86ACCP board
> 2 x CPM-SDSK-2321S-ELS (X&Y)
> 1 x CPM-SDSK-3421S-ELS (Z)
> 
> Any thoughts are welcome.
> 
> 
> Sent from my iPhone using Tapatalk


have you tuned acorn performing the overall turns turns ratio and steps per revolution, if not please do so and report back


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## adamyq

LucidCnC said:


> have you tuned acorn performing the overall turns turns ratio and steps per revolution, if not please do so and report back



I’m not sure if the answer is yes or if I have no idea what you are talking about. I went through the CNC 12 wizard screens, selected my hardware and entered in the required information which should be identical to koenbros. I have not yet quantified the backlash because I cannot yet trust the movement increments.

I’ll do some more digging when I get home, but any guidance you could provide in the meantime would be appreciated.


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## LucidCnC

adamyq said:


> I’m not sure if the answer is yes or if I have no idea what you are talking about. I went through the CNC 12 wizard screens, selected my hardware and entered in the required information which should be identical to koenbros. I have not yet quantified the backlash because I cannot yet trust the movement increments.
> 
> I’ll do some more digging when I get home, but any guidance you could provide in the meantime would be appreciated.
> 
> 
> Sent from my iPhone using Tapatalk


if you haven't seen this youtube video yet, it's a good start;





Also with the centroid acorn install manual you can review the chapter for machine motion tuning, even with the same machine, motors and screws you should tune it


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## adamyq

LucidCnC said:


> if you haven't seen this youtube video yet, it's a good start;
> 
> 
> 
> 
> 
> Also with the centroid acorn install manual you can review the chapter for machine motion tuning, even with the same machine, motors and screws you should tune it



I will take a look, just really strange that I am off by exactly a factor of eight. Is there someway to do a complete reset of all settings both domestic to the acorn as well as the CNC12 software and start fresh?


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## Firebrick43

deleted


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## adamyq

Firebrick43 said:


> Are you taking the backlash out before you are measuring? IE go one way, then go .100" the other(to take out backlash), zero the indicator, then command another .100"



No I understand the process, but my movements don’t currently match my commands, so I haven’t been able to execute this process yet.


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## koenbro

I would not worry about backlash yet. Two-three thou will not explain what you have.

Is it possible your system is sending 8x more impulses ? It is uncanny you get 0.8" of movement when you command 0.1". I am attaching a screen grab of the Clearpath tuning setup in the hope it helps.


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## adamyq

koenbro said:


> I would not worry about backlash yet. Two-three thou will not explain what you have.
> 
> Is it possible your system is sending 8x more impulses ? It is uncanny you get 0.8" of movement when you command 0.1". I am attaching a screen grab of the Clearpath tuning setup in the hope it helps.
> 
> View attachment 403703



So I don’t even recognize this screen that you just sent, guess I have some more research to do. 


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## koenbro

Another area worth checking is this:
Acorn > setup > config > mach > motor:







The metric -> inch conversion needs that 5.08 factor. Plus the steps/rev have to be correct.


Let me know if any of these help.


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## koenbro

adamyq said:


> So I don’t even recognize this screen that you just sent, guess I have some more research to do.



It is the Clearpath MSP 2.0 tuning software that you have to download from Teknic.com and tune your mechanics BEFORE futzing with Acorn. Is it possible your steps/rev are off?


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## koenbro

GB21 said:


> Yes I am using the acorn with swissi's probeapp over on the centroid forum.  https://centroidcncforum.com/viewtopic.php?f=60&t=6149&sid=0d45b3d3b0d6c1417d13925c36c32000
> Even though its a "simple" atc It took about 2-3 days of cad work to design and another FULL week of work to move the motor controller box off the head of the mill, machine all the parts, wire everything and plumb the pneumatics. I am currently reading and trying to learn how to write/edit custom macros and plc programming so someday I can make carousel atc. Its a lot of work but its worth it when I can walk away from the mill and do other things while its running.



 I never realized there is an ATC feature in swissi's app. Amazing!

What is the max tool count in the comb design? Five?


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## adamyq

koenbro said:


> It is the Clearpath MSP 2.0 tuning software that you have to download from Teknic.com and tune your mechanics BEFORE futzing with Acorn. Is it possible your steps/rev are off?



This was the ticket. I assumed the firmware came with the right pulses/rev, and I never even plugged them. I bought the USB cable with the package, but assumed it was just for troubleshooting. Did a quick check and everything appears to be spot on now. 

I was reading some of the manual on the auto-tuning with it connected to the mechanical system. Have you all done that?


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## koenbro

adamyq said:


> This was the ticket. I assumed the firmware came with the right pulses/rev, and I never even plugged them. I bought the USB cable with the package, but assumed it was just for troubleshooting. Did a quick check and everything appears to be spot on now.



Lemme guess: you were set at 800 steps/rev, which might be the factory default?

And yes you have to (auto)tune your system. If you change it (add a vise for example) you have to repeat the tuning.


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## adamyq

koenbro said:


> Lemme guess: you were set at 800 steps/rev, which might be the factory default?
> 
> And yes you have to (auto)tune your system. If you change it (add a vise for example) you have to repeat the tuning.



Bingo. Knew it had to be something like this. 


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## koenbro

Can anyone help me interpret the trip map for my sensor, obtained with swissi's app in a 1" bore?


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## akschu

Looks like I'm jumping on the bandwagon myself.  My 728vt has been sitting in the corner of my shop for about a month, pulled the trigger on the clearpath servos and the acorn today.   My requirements are pretty simple to start off, I just need to machine some aluminum sheet for some panels, but nothing is more than 5x8 and I didn't want to purchase a router when the money could be spent on servos.


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## Loftfan

Hi guys! I've just gotten my 728VT up and running and I'm working out the bugs. It's good to see that my measured backlash is similar to others experience. 

After fixing a VERY loud (and jumpy) Z-axis (I had loose phase connections at my Stepperonline CL86T driver), I'm chasing down another issue with the Z-axis. 

I seem to be chasing tool offsets, but that would be related to the issue detailed below:

My Z-axis doesn't return to the same position after a move, or several moves over 2 inches (~10 turns of the ballscrew). Moving 0.100" is no issue, it comes right back to the same spot, using a test indicator in a drill chuck. A 2+ inch move won't reliably come back to the same place. It could be 0.010"-0.015" off after a few repetitions, and gets progressively worse with more moves. I'll come back with what I find. Right now, I don't have a clue.


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## GB21

Loftfan said:


> Hi guys! I've just gotten my 728VT up and running and I'm working out the bugs. It's good to see that my measured backlash is similar to others experience.
> 
> After fixing a VERY loud (and jumpy) Z-axis (I had loose phase connections at my Stepperonline CL86T driver), I'm chasing down another issue with the Z-axis.
> 
> I seem to be chasing tool offsets, but that would be related to the issue detailed below:
> 
> My Z-axis doesn't return to the same position after a move, or several moves over 2 inches (~10 turns of the ballscrew). Moving 0.100" is no issue, it comes right back to the same spot, using a test indicator in a drill chuck. A 2+ inch move won't reliably come back to the same place. It could be 0.010"-0.015" off after a few repetitions, and gets progressively worse with more moves. I'll come back with what I find. Right now, I don't have a clue.


You are losing steps. I have the same machine and fought the same battle. Hunting down the problem can be frustrating and has a lot of mechanical and electronic variables. My issue was not using rc snubbers on all coils. It has been running great now for 2 years but don't ask me how many times I jogged up and down to figure that one out


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## Loftfan

GB21 said:


> You are losing steps. I have the same machine and fought the same battle. Hunting down the problem can be frustrating and has a lot of mechanical and electronic variables. My issue was not using rc snubbers on all coils. It has been running great now for 2 years but don't ask me how many times I jogged up and down to figure that one out


If I am losing steps, the closed loop stepper kits I bought would appear to be useless. 

Can you go into more detail on your RC snubber installation?


----------



## GB21

I am using stepper online Y series drives and my mill holds 0.001 all day. I went with these drives because the accept 24v and I am using centroid acorn and didn't want to drop to 5v signal but CL86T and CL86Y are pretty much the same. Snubbers or quencharc's are likely not your problem yet if your just jogging around. They are necessary on anything that has a coil such as vacuums and solenoids for example I use pneumatic solenoid valves for mist coolant, ATC and my 4th axis. I use cheap ones like these https://www.amazon.com/gp/product/B09F116Y27/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

I don't know what controller you are using but keep in mind they claim a max input of 200kHZ frequency but these drives are not fast enough as verified by a oscilloscope( that took me another year to figure out) . I set mine to 100kHZ 
​​


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## Loftfan

GB21 said:


> I am using stepper online Y series drives and my mill holds 0.001 all day. I went with these drives because the accept 24v and I am using centroid acorn and didn't want to drop to 5v signal but CL86T and CL86Y are pretty much the same. Snubbers or quencharc's are likely not your problem yet if your just jogging around. They are necessary on anything that has a coil such as vacuums and solenoids for example I use pneumatic solenoid valves for mist coolant, ATC and my 4th axis. I use cheap ones like these https://www.amazon.com/gp/product/B09F116Y27/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1
> 
> I don't know what controller you are using but keep in mind they claim a max input of 200kHZ frequency but these drives are not fast enough as verified by a oscilloscope( that took me another year to figure out) . I set mine to 100kHZ
> ​​


Thanks for the tips, I'll be adding a coolant solenoid soon. 

I'm also using Centroid Acorn. I'll make the adjustment you did.


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## Loftfan

I found a very likely cause for my issue of the Z-axis drifting downward. I locked the gib on the head slide and actuated the Z-axis. What I saw surprised me (see video in link)!






After this video, I tightened the locknut and actuated the axis a few more times until I had 0.015" of drift. Tightening the nut again brought the head position back to where it started.

I bought the "precision" ballscrew kit from Precision Matthews

When I was tightening the ballscrew locknuts, I never did get a good bite on the setscrews. Apparently, my Z-axis locknut has been backing out for a while now. I suspect that my small allen wrenches are worn out, because none of them fit this tiny 2mm setscrew well. I bought a new set of wrenches yesterday and I'll try to get it locked down. I checked the X-axis, and it was loose too. I bet the Y is the same case. 

What is the torque spec on the ballscrew locknuts? There wasn't any guidance in the kit. These locknuts are grooved to accept a small hooked spanner wrench. I'll see if I can buy a torque adapter for my torque wrench. I'm guessing the torque spec is somewhere in the in-lb scale.


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## GB21

Loftfan said:


> I found a very likely cause for my issue of the Z-axis drifting downward. I locked the gib on the head slide and actuated the Z-axis. What I saw surprised me (see video in link)!
> 
> 
> 
> 
> 
> 
> After this video, I tightened the locknut and actuated the axis a few more times until I had 0.015" of drift. Tightening the nut again brought the head position back to where it started.
> 
> I bought the "precision" ballscrew kit from Precision Matthews
> 
> When I was tightening the ballscrew locknuts, I never did get a good bite on the setscrews. Apparently, my Z-axis locknut has been backing out for a while now. I suspect that my small allen wrenches are worn out, because none of them fit this tiny 2mm setscrew well. I bought a new set of wrenches yesterday and I'll try to get it locked down. I checked the X-axis, and it was loose too. I bet the Y is the same case.
> 
> What is the torque spec on the ballscrew locknuts? There wasn't any guidance in the kit. These locknuts are grooved to accept a small hooked spanner wrench. I'll see if I can buy a torque adapter for my torque wrench. I'm guessing the torque spec is somewhere in the in-lb scale.


Those tiny setscrews are worthless. Mine kept coming loose on the z and y also. I used jam nuts and tightened them against the locknut with a drop of threadlocker. problem solved.  You should start your own build thread so we can follow along.



			https://www.amazon.com/Hillman-Group-43811-M12-1-75-10-Pack/dp/B00IZFS8EC


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## Loftfan

GB21 said:


> Those tiny setscrews are worthless. Mine kept coming loose on the z and y also. I used jam nuts and tightened them against the locknut with a drop of threadlocker. problem solved.  You should start your own build thread so we can follow along.
> 
> 
> 
> https://www.amazon.com/Hillman-Group-43811-M12-1-75-10-Pack/dp/B00IZFS8EC


Many thanks for your guidance on adding the locknuts. After this was fixed, I burnt up my Stepperonline CL86T Z-axis driver (don't control the v3 version with 24v. They need an in-line resistor!). Once that was replaced, I'm repeatable within a thousandth!

My homemade Fogbuster is working great, too. I have the four-way hose fittings (which were the only parts not available on the market) for the water filter housing for sale on Etsy - Click Link Here.


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## cxagent

Loftfan said:


> Many thanks for your guidance on adding the locknuts. After this was fixed, I burnt up my Stepperonline CL86T Z-axis driver (don't control the v3 version with 24v. They need an in-line resistor!). Once that was replaced, I'm repeatable within a thousandth!


Wait - what about the CL86T needing a in-line resistor???? Where can I find more information before I power mine up?


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## Loftfan

cxagent said:


> Wait - what about the CL86T needing a in-line resistor???? Where can I find more information before I power mine up?



Link to v3.0 Manual

If you have a v3.0 controller WHICH IS STILL BEING SHIPPED TWO YEARS AFTER V4.0 WAS INTRODUCED, look at pg7 in the manual. There, the resistor values are given. My controller uses 24v, and my CL57T's contained a switch to select between 24v control and 5v control. I assumed the CL86T was the same version, but it wasn't. I burnt a tiny 250ohm resistor on the circuit board for the direction circuit. 

I have 2kOhm resistors in line now. My replacement driver was another CL86T v3.0


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## koenbro

As my system has been up about a year, it's time to clean it, lubricate, tighten, and just give it a general go-over.

I just had my x-axis double nut repacked and tightened by Dave who makes the Arizona CNC kits. As many others can testify, Dave is very knowledgeable and a nice guy to talk to. I am also lucky that he lives in the Phoenix metro area and he welcomed me in his shop. I am going to post some updates on the machine's performance.


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## sakumar

I'm trying to tighten my Z-axis gib to reduce backlash and have a couple of questions.

Using a dial test indicator I was able to test that the ballscrew itself has almost 0 backlash. By the time the spindle head starts to move upwards though there is 0.07mm (~0.003") backlash. I've tried tightening the gib but seem to have 'bottomed out.' Actually the gib is so far out in one direction that the screw that holds it in place is starting to bend away from it.

So the questions: Does the direction of the gib taper matter? Mine tightens as it is moved upwards.
Anyone else run into this issue? What was the solution? Can I order a slightly thicker gib from P-M?


----------



## sakumar

sakumar said:


> I'm trying to tighten my Z-axis gib to reduce backlash and have a couple of questions.
> 
> Using a dial test indicator I was able to test that the ballscrew itself has almost 0 backlash. By the time the spindle head starts to move upwards though there is 0.07mm (~0.003") backlash. I've tried tightening the gib but seem to have 'bottomed out.' Actually the gib is so far out in one direction that the screw that holds it in place is starting to bend away from it.
> 
> So the questions: Does the direction of the gib taper matter? Mine tightens as it is moved upwards.
> Anyone else run into this issue? What was the solution? Can I order a slightly thicker gib from P-M?


OK -- I guess I'll answer some of my questions.
The direction of the gib taper _does_ matter. I was wrong about the direction for the Z-axis. The gib is thicker at the top and thinner at the bottom. So it tightens as the gib is moved (pushed) downwards.
P-M can provide a gib which is slightly oversized but you'll have to machine it down to size.

Even after quite a bit of trial and error, I could reduce the backlash to around 0.06mm (between 2 and 3 thousands of an inch). At some point, tightening the gib even more made it worse. I am convinced that due to the cantilever design of the z-axis lift mechanism this much play is inherent. To reiterate, there is no backlash at all at the bottom of the ballscrew itself which I tested with a dial test indicator inserted into the Z-column slot. But by the time the spindle head starts to move in the other direction there is 0.06mm of backlash. I think (hope) that the software backlash compensation will be able to take care of this.


----------



## B2

Hi @sakumar 

I have spent a lot of time with my gibs on the PM940M.    I am not complaining, but here are some of my thoughts for you.  

Yes, pushing in on the larger end provides tightening.  The screw on the small end is for clamping it in place after moving the gib.  However, if you leave it loose, or remove the gib screws and run the saddle along the ways then the gib will slide back and forth and can even get very tight.  So after adjusting the gib with the screws always tighten the screws on both ends to hold the gib in place.   Sure enough if you do not clamp the gib then the backlash can be different in the two directions!

You do not want the clamping screw to pinch the end of the gib into the ways.  This is especially a hazard at the small gib end.  If so this is applying lots of pressure at this one point, not a gib function at all as all .... the drag/friction is at only one end/point along the gib!  

Yes, I found that if you adjust the gib too tight then the backlash can increases .. and it can increase significantly.  If you tighten it too much it is equivalent to applying a lock.  This backlash is a function of the load being driven by the motor etc.  The drive load (motor coupling, bearings, lead screw itself, ball nut, gib, etc) tends to cause the lead screw to act like a spring being wound rather than resulting in motion of the saddle... when this drive load is heavier the backlash increases.   I found that my ways, Y-axis, are not parallel, resulting in the gib being tighter at the wide area... and so the backlash increases at the wide position along the ways simply because the gib is too tight (increased load).  I am still studying this in my spare time and trying to fix it by working on the ways....,  so far I have made a huge improvement.  Unless you rework the ways, you pretty much have to live with the backlash at the worst position or loosen things up so much that the saddle does not remain square.   When I tightened up my gib where the ways are the closest together... then I found that the backlash, where the ways were wider, went from 0.00x to 0.0xx.  Wow!  You could even feel the springing of the y-axis crank handle.  

I actually found that measuring backlash is the most effective method I have for adjusting the gib.  

It is easy to compensate for backlash when cutting straight cuts.  The software will not be able to do so on a curve, so I think circles always become ellipses.  However, how often are you machining a circle in the plane of the z axis!  When I am drilling an array of holes you can easily compensate for backlash by always approaching the next hole from the same directions.   This is simple if you are writing your own g-code.  

The gear driven head on my 940 is very heavy.  I estimated it to be between 250 and 275#s +-.   Nod is a something you live with and I think this weight actually bows the distance between the ways (pinches the ways toward each other) in the center position.  I am not saying that the column bends over, it is just being collapsed together due to the weighted cantilevered head ... a very small amount showing up as way spacing decrease of a few thousands.  This means that the head nods and the gib becomes looser in some positions.  So backlash varies with vertical position.  The solution to this is to reduce the head weight .. or some how make the column even stronger.  Maybe a counter balance of some type.  I think the head on the PM728 is significantly lighter and the machine is suppose to be much better made all the way around... so hopefully this is not much of an issue for you.  

So, you might want to try to set the gib when you are at the top of the column by monitoring the backlash (setting it to be small) at this position... and then measure it at the bottom to see if it is still small.  Of course the nod at the bottom position may increase.

Another thought, check the lead screw alignment.  Assuming that the lead screw only has bearings at the motor end (top) then the bottom is free to flex when the ball nut is at that location, but it for some reason the ball nut is not properly aligned at the upper position and the lead screw cannot flex then this tightness can cause a load ... backlash.  

Good luck.

Dave L.


----------



## sakumar

B2 said:


> Hi Dave L.


Thank you for the detailed response.
As you note, the Z-axis backlash is of less importance than the X and Y. I am getting about 0.02mm (less than 1/1000") backlash on X and Y.

I have decided to more or less live with the Z backlash of 0.07mm and rely on software compensation.

One problem compared to manual operation is that it is hard to get a feel for how tight the ways are and the mongo Clearpath servo motor has a lot of torque. One time I locked the z-axis, then forgot I had done so and jogged it up and found that the motor could still drag everything up! It made a different sound alerting me that there was a problem.

I have also added a jam nut to the locking nut on top of the z-ballscrew. That part is working perfectly. I inserted a DTI inside the Z-column just below the ball nut and it has no backlash at all! So all the backlash is due to the play and flex in part #14 in the diagram below. I have installed a Priest Tool power drawbar thus making the head heavier so that is also contributing to the problem.

Sanjaya


----------



## GB21

sakumar said:


> Thank you for the detailed response.
> As you note, the Z-axis backlash is of less importance than the X and Y. I am getting about 0.02mm (less than 1/1000") backlash on X and Y.
> 
> I have decided to more or less live with the Z backlash of 0.07mm and rely on software compensation.
> 
> One problem compared to manual operation is that it is hard to get a feel for how tight the ways are and the mongo Clearpath servo motor has a lot of torque. One time I locked the z-axis, then forgot I had done so and jogged it up and found that the motor could still drag everything up! It made a different sound alerting me that there was a problem.
> 
> I have also added a jam nut to the locking nut on top of the z-ballscrew. That part is working perfectly. I inserted a DTI inside the Z-column just below the ball nut and it has no backlash at all! So all the backlash is due to the play and flex in part #14 in the diagram below. I have installed a Priest Tool power drawbar thus making the head heavier so that is also contributing to the problem.
> 
> Sanjaya


Did you check the preload on the double ballnut? I went down this same road chasing gib tightness and bearing preload for hours but it was just masking the real problem. Once I fixed my ballnut I went from 0.0045 to 0.0015 backlash if I remember correctly.


----------



## sakumar

GB21 said:


> Did you check the preload on the double ballnut? I went down this same road chasing gib tightness and bearing preload for hours but it was just masking the real problem. Once I fixed my ballnut I went from 0.0045 to 0.0015 backlash if I remember correctly.


No I didn't -- can you provide a link on how to check the preload and also how I can fix it if I find it is out of spec?

But to reiterate -- I am pretty sure I'm getting almost zero backlash at the bottom of the ballnut as measured by a DTI inserted into the slot in the Z column.


----------



## GB21

Mine was obvious, If you can get a feeler gauge between the spacers its not preloaded. Others had the same problems with the pm ballscrews. if you do a quick search you will find the threads. Below is a video on how loose mine was. I talked to Matt and he relayed it back to the factory so hopefully the issue was resolved a long time ago but it never hurts to check. I can tell you that the cast iron part is not flexing... I am actually running one I made from 6061 with extra weight on the head and have no issue.  My guesses are the M8 bolt moving(the boss is not a precision fit, ballnut preload, angular bearing preload/or quality,  gib too tight.


----------



## B2

Hi @sakumar 

Good morning.     If I could get my backlash down to your 0.02mm = 0.0008" I would be really happy!!!  My current backlash on my y-axis is more like 0.003 to 0.004" and I am still working on it via losts of measurements and then modifying the ways.   It used to be a lot worst.     x and z axis are just as bad, but I have not begun to work on them.    When I make my gib completely loose the best I get is about 0.002-0.0025" so when I get to that point I may work on other parts.   Obviously I do not want the gib completely loose or the table/saddle will tilt, rock, rotate .. swivel.  

Yes, it is amazing how much weight the CNC motors can move.  My 940 has steppers and it can drag the Z-head up even when the locks are on.  This is how I first discovered there was a problem with my gib clamp.  The stepper would lower the head and not miss any steps, but when it lifted the head it would sometimes miss steps.  This could be quite sever and was not due to the locks!   Anyway,  I stopped using the locks after I took my z-axis out (much later on) and found that the two lock screws were leaving big gouges in the back side of the gib.  I wondered if these could be warping the gib.    However, even this was useful information.  I could see that the gouge marks had been moving around, indicating that my gib position was not stable.  I also realized that gib was cut improperly and was being pinched against the dove tail at the small end rather than just being held in place.  So it was acting like a clamp.  I am guessing that because of this pinching, the factory also cut the gib off too short.   I fixed this, but first you have to discover it.

You have double thrust bearings and a ballnut that can be adjusted.  I wish I did.  I agree with @GB21 take a look at this.



sakumar said:


> One problem compared to manual operation is that it is hard to get a feel for how tight the ways are and the mongo Clearpath servo motor has a lot of torque. One time I locked the z-axis, then forgot I had done so and jogged it up and found that the motor could still drag everything up! It made a different sound alerting me that there was a problem.



Using backlash to set your gibs (with a CNC system):

So you have clear path servo motors rather than steppers.  However, I think they still function more or less like steppers... I think they take in a step signal from the controller and then the motor's internal electronics moves the shaft until the step is reached.  So the shaft turns and if the saddle does not move it is probably because of some slack (or spring being wound) in the rest of the chain of components between the motor and the saddle.   Anyway, I think you can use my approach toward measuring backlash to set your gib position.  Gib too tight and the backlash increases.   Too loose and the backlash is determined by some machine part other than the gib setting.    The procedure is the same as any backlash measurement but I use the CNC pendant to move 0.001" steps.   Place the micrometer probe between the spindle and a block on the table.  Traverse in one direction a sufficient amount to over come any backlash.  Record the micrometer reading or zero it.  In the reverse the travel direction supply a signal to the motor to tell the motor to move say ~ 0.010" as determined by the pendant (not the micrometer).  I do this in 0.001" steps and watch the micrometer dial.  Now measure the actual motion as determined by the micrometer.  The difference between the actual distanced moved vs. the requested move is the backlash.  I found this technique to be very effective, especially if you move farther than it takes to just cause the micrometer to "start to move" ... as even the backlash value is non-linear.    If you did not see any backlash then tighten the gib until you do.  When the backlash starts to increase then back the gib tightness off a bit.  You might want to note the gib screw depth.  You should do this at several saddle positions along the way until you find the place where the backlash is the smallest.  This will be the point where the two dovetails of the way are the closest together.  Set the backlash here to just be governed by the gib tightness.  Then measure the backlash at other saddle positions and see if the dovetails of the ways are parallel.   (Note, the gib/way interface is not a perfect match.  It maybe an awful match.  In which case the gib may actually only be contacting at 2 points or a small region along the saddle length if it is truly unbending/stiff.  These two points could be close together or far apart.  If the ways are not perfect(?) then the contact points could actually be different depending upon the saddle travel position.   If the gib is made with an incorrect tapper, to match the saddle dovetail tapper, then the gib will only contact near one end.  If this is really bad you might be able to see it in via the saddle rotating about the gib contact point.)

I have not done it in detail, but I think you can actually calibrate the backlash measurement to determine the dovetail/way parallel error.  You can determine the tapper of the gib and so when you screw in the gib screw you know how far it went in and so you know now much spacing you have used up between the dovetails with the gibs increased thickness.   Since, I have not tried to work out these details I am not for sure how well this will work, especially since it is probably not a linear response.   Nevertheless, since I am still working on the dovetail parallelism of my machine I my work at this.  People usually measure the parallelism by fitting cylinder rod in the dovetails to make contact to the dovetails at two points... and then using a large micrometer to measure the distance between the outsides of cylinders.    Do this at several points along the way travel and the difference is the parallelism error.  I am currently building a micrometer to do this well... I hope.  However this has its own limitations in that the surface that the saddle sits on is outside of the dovetails.  If this surface is not flat then the cylinder measurement may not be valid/accurate as the cylinder only touches at two points.   So I think the backlash measurement could actually be preferred.    

By the way, if the gib is really too tight you can feel it as you had crank the lead screw.  When it is way over tight or there is some other binding you will turn the handle and when it is released it will spring back ... a bit.   Of course you have to power off the servo motors to do this.  With stepper motors one might also observe the magnet cogging.

Still learning.

Dave L.


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## sakumar

GB21 said:


> Mine was obvious, If you can get a feeler gauge between the spacers its not preloaded. Others had the same problems with the pm ballscrews. if you do a quick search you will find the threads. Below is a video on how loose mine was. I talked to Matt and he relayed it back to the factory so hopefully the issue was resolved a long time ago but it never hurts to check. I can tell you that the cast iron part is not flexing... I am actually running one I made from 6061 with extra weight on the head and have no issue.  My guesses are the M8 bolt moving(the boss is not a precision fit, ballnut preload, angular bearing preload/or quality,  gib too tight.


Thanks so much for the tips!

The M8 bolt was definitely a problem. See photo below (although the shift is exaggerated due to parallax) . At some point it had shifted to the left and as a result pulled the ballscrew to the left as well. I loosened it, adjusted the position and retightened it. Google shows that an M8 socket head screw should be tightened to 41 Newton-meters. My smaller Tekton torque wrench only goes up to 28 N-m, so I tightened it to at least that much.

After that I also noticed a distinct groaning noise when the head changed direction. That was because I had tightened the gib too much. Eventually I loosened it by a little more than two turns and the noise went away.

So now the backlash on the Z-axis is about 0.0018" (0.045 mm) and I'm very satisfied with that.


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