Newbie converting a PM-728VT

All things related to the Centroid Acorn CNC Controller

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DesertRider
Posts: 56
Joined: Mon Nov 30, 2020 6:49 pm
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Re: Newbie converting a PM-728VT

Post by DesertRider »

martyscncgarage wrote: Thu Feb 25, 2021 12:58 pm Real time feedback requires an encoder to be mounted at 1:1 to the spindle with timing pulleys and belt. Reach out to Franco and see if he'll print and sell you a bracket. He is a member on this forum
The PM has a tachometer, and you can link up the 0-10V adapter board for the Acorn connection in such a way that the tachometer is not disabled. I wonder if there is a way to feed back the signal from teh mill's built-in tachometer to the Acorn. That would be the most straightforward way, if doable

I have written Franco, hope to hear back. Thanks for the suggestion.

I'll say it again, you must use signal isolation between Acorn and your spindle drive. You'd better ask Precision Matthews if that board provides signal isolation for the 0-10vdc analog input.
[/quote]

I called PM to ask about the signal isolation. The gentleman I talked passed my question on to the factory and I got a reply the next day, stating that "both the adapter and the control board are isolated." I have made the wiring, but am not able to to set the RPMs the right way. Used the steps you describe in your video : 300RPM max, and ran the spindlebenchtest.cnc, but when I command 500 rpm in Acorn I get 8xx rpms on the spindle tachometer. Will rerun the benchtest hoping it will reset it.
martyscncgarage
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Re: Newbie converting a PM-728VT

Post by martyscncgarage »

All the bench test does is prove the analog outpit is functional. It is up to you to tune your spindle drive correctly. Spindle bench test does not calibrate anything. If the spindle benchtest passes, change the high spindle speed from 3000 to your known spindle RPM in the wizard.

No you CAN NOT input anything other than a line driver/differential encoder input to Acorn.

I hope PM is right about signal isolation on the Analog input lines.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
DesertRider
Posts: 56
Joined: Mon Nov 30, 2020 6:49 pm
Acorn CNC Controller: Yes
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Oak CNC controller: No
CNC Control System Serial Number: 1116203993
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
Location: Phoenix, Az

Re: Newbie converting a PM-728VT

Post by DesertRider »

Based on the latest recommendations from Centroid, i have redone the wiring of the motors today -- I had originally cut off the molex and wired directly into the Acorn terminals. Today I have crimped molex spades back onto the wires and plugged in a CNC4PC ACCP board and followed Marty's wiring recommendations to wire relays etc. The system works well with the new setup.

Have just ordered a KP-3 probe, and working next on fabricating a base for the mill.
DesertRider
Posts: 56
Joined: Mon Nov 30, 2020 6:49 pm
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DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
Location: Phoenix, Az

Re: Newbie converting a PM-728VT

Post by DesertRider »

martyscncgarage wrote: Sat Feb 27, 2021 3:17 pm
Marty do you know someone in the Phoenix metro who has a lathe and is willing to machine a short threaded 1/4" or 6mm hole in the top of my drawbar? I got the OMron encoder and jerry - rigged it on top without Franco's belt system, but I need to drill and tap a hole in the drawbar. I am of course willing to pay for the service. Thank you!
tblough
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Re: Newbie converting a PM-728VT

Post by tblough »

Careful using the drawbar. It's a loose fit in the spindle hole and tightens down in a different place each time.
Cheers,

Tom
Confidence is the feeling you have before you fully understand the situation.
I have CDO. It's like OCD, but the letters are where they should be.
martyscncgarage
Posts: 9912
Joined: Tue Mar 28, 2017 12:01 pm
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Re: Newbie converting a PM-728VT

Post by martyscncgarage »

DesertRider wrote: Thu Mar 11, 2021 1:03 am Based on the latest recommendations from Centroid, i have redone the wiring of the motors today -- I had originally cut off the molex and wired directly into the Acorn terminals. Today I have crimped molex spades back onto the wires and plugged in a CNC4PC ACCP board and followed Marty's wiring recommendations to wire relays etc. The system works well with the new setup.

Have just ordered a KP-3 probe, and working next on fabricating a base for the mill.
I had just discovered you want to move the enable jumpers on Axis used from HARD enable to SOFT enable.
This way if you get a drive fault you can reset the drives by cycling the Estop button. Also the motors will not enable until CNC12 is in the ready state (NoFault relay output closes)

I'll put an update in the benchtest video very soon.
Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
martyscncgarage
Posts: 9912
Joined: Tue Mar 28, 2017 12:01 pm
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Location: Mesa, AZ

Re: Newbie converting a PM-728VT

Post by martyscncgarage »

tblough wrote: Thu Mar 11, 2021 7:57 am Careful using the drawbar. It's a loose fit in the spindle hole and tightens down in a different place each time.
Like Tom said, that's not a good place for an encoder.
Take and post pictures of you spindle maybe we can provide some ideas


Since you are in the Phoenix area, you should consider joining the Valleymetal Club. Search for us on www.groups.io and subscribe there. We communicate via the group is io email system. We try and meet once a month. But thanks to Covid, I suspended the meetings temporarily. There are guys in the club willing to help each other out.
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
DesertRider
Posts: 56
Joined: Mon Nov 30, 2020 6:49 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
CNC Control System Serial Number: 1116203993
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
Location: Phoenix, Az

Re: Newbie converting a PM-728VT

Post by DesertRider »

Thank you for the suggestion, I have just sent in a request to join Valley Metal.

As for the drawbar, I made a simple bracket that connects the encoder to a second L bracket that attaches to the motor housing.
Screen Shot 2021-03-11 at 9.01.17 AM.png
This way I can attach and remove the encoder quickly:
IMG_7195.JPG
Seems to work well, and leaves room at the bottom for the 11mm wrench to loosen the collet. Not sure why this idea wouldn't work. Of course the current implementation (11mm socket and a 3/8" square to 1/4" hex adaptor) is crude and temporary, but if I could get a 6 mm rod, one end inserted into the shaft coupler, the other threaded into the end of the drawbar, that would be more elegant.
DesertRider
Posts: 56
Joined: Mon Nov 30, 2020 6:49 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: No
Oak CNC controller: No
CNC Control System Serial Number: 1116203993
DC3IOB: No
CNC12: Yes
CNC11: No
CPU10 or CPU7: No
Location: Phoenix, Az

Re: Newbie converting a PM-728VT

Post by DesertRider »

martyscncgarage wrote: Thu Mar 11, 2021 8:15 am
I had just discovered you want to move the enable jumpers on Axis used from HARD enable to SOFT enable.
This way if you get a drive fault you can reset the drives by cycling the Estop button. Also the motors will not enable until CNC12 is in the ready state (NoFault relay output closes)
THANK YOU for that. Yesterday I got a drive fault (by overtraveling the Y axis, without crashing) and had a hell of a time releasing it. Hopefully the "soft" settings solves that.
martyscncgarage
Posts: 9912
Joined: Tue Mar 28, 2017 12:01 pm
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CNC Control System Serial Number: none
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CNC11: Yes
CPU10 or CPU7: Yes
Location: Mesa, AZ

Re: Newbie converting a PM-728VT

Post by martyscncgarage »

DesertRider wrote: Thu Mar 11, 2021 12:12 pm
martyscncgarage wrote: Thu Mar 11, 2021 8:15 am
I had just discovered you want to move the enable jumpers on Axis used from HARD enable to SOFT enable.
This way if you get a drive fault you can reset the drives by cycling the Estop button. Also the motors will not enable until CNC12 is in the ready state (NoFault relay output closes)
THANK YOU for that. Yesterday I got a drive fault (by overtraveling the Y axis, without crashing) and had a hell of a time releasing it. Hopefully the "soft" settings solves that.

All it will do if you wired it up like I did, is allow you to cycle the drives and reset them.
If you over travelled an axis, then you don't have your soft limits setup correctly.
Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
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