Precision Matthews PM-728VT CNC conversion

[koenbro]

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]

@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]

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

 

[adamyq]

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]

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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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

 

[adamyq]

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

 

[adamyq]

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.