Centroid Community CNC Support Forum

martyscncgarage wrote: ↑Sun Feb 14, 2021 12:00 pm

cncsnw wrote: ↑Sun Feb 14, 2021 5:51 pm

Thank you gentlemen, I have ordered 3 NPN NC sensors from AutomationDirect. Hopefully they will play with the Acorn.

DesertRider wrote: ↑Sun Feb 14, 2021 9:51 pm

martyscncgarage wrote: ↑Sun Feb 14, 2021 12:00 pm

cncsnw wrote: ↑Sun Feb 14, 2021 5:51 pm

Thank you gentlemen, I have ordered 3 NPN NC sensors from AutomationDirect. Hopefully they will play with the Acorn.

Should be no problem provided you power them with +24VDC
Keep us posted!
Marty

I have run the spindlebenchtest but my mill has a max speed of 4250. How can i configure the voltage output to run the apindle over 3000 rpm?

You'll need to adjust the max frequency of your VFD to change the motor RPM.

I am not sure how to adjust the frequency on the PM 728. Here are some photos of the circuit (nothing obvious to adjust), front panel (the potentiometer is how you adjust the rpm), and motor. Sorry about the bad photos, could not reach better. So do I adjust the VFD, how else would I increase the range of the Acorn signal to reach 4200 RPM?

BE VERY CAREFUL Connecting that drive to Acorn Analog inputs. There needs to be signal isolation between them.
Do you have a manual for that BLDC Drive? Post it here.

Generally speaking, after you run the Spindle Bench test, go into the SPINDLE section of the Wizard and change the value to your Max Spindle RPM. In your case, change it from 3000 to 4250.

Is your spindle motor belted to the spindle at 1:1? Pulleys? You don't provide any information about that either....we can't "SEE" what you "SEE"

Marty

Did you go watch Franco's videos on this same conversion?
DO NOT CONNECT ACORN to that drive without a signal Isolator!

martyscncgarage wrote: ↑Wed Feb 24, 2021 10:59 am BE VERY CAREFUL Connecting that drive to Acorn Analog inputs. There needs to be signal isolation between them.
Do you have a manual for that BLDC Drive? Post it here.

Thank you Marty for these replies, they were very helpful, as always. I stopped the project and watched Franco’s videos. I do not have that isolation board he uses, but I do have the factory adaptor that PM sells with these mills. I have wired it up last night and it does work. I will post a quick video today or tomorrow with as much info as I can gather.

The motor uses a belt with two pulleys (low-, and hi-speed) so the spindle speed and the motor speed are different, and will need some thought. Not sure how I’m going to solve that. Can you recommend some technique to measure the spindle speed in real time and feed it back to the Acorn? I do not have a 3D printer so Franco’s method with the bushing will not work for me.

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

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.
Marty