Centroid Community CNC Support Forum

Here is the manual for the BOSS spindle controller.

Min and max are for the spindle rpms, not the motor. If you set max to 10,000rpm, and you issue a M3 S10000, then the analog out will be 10V. It's up to your motor controller (VFD) to decide what to do with that 10V.

FKreider wrote: ↑Mon Apr 26, 2021 3:40 pm Hi Marty,

Yes I can currently raise and lower the speed via the VCP but the numbers shown on the screen are WAY off from what the actual machine rpm is.

Let me dig up the manual.

Should I be putting in the min/max speeds for the electric motor (aka 7200 rpm max) or for the machine (10k) ?

You NEED to put in the RPM numbers that the machine was shipped with.
If its max spindle speed was 7200, then put in 7200.
If its min spindle speed was 400 (example), then put in 400 for MIN

Please note, CNC12 does NOT close a spindle motor loop. It issues an analog output that is linear with the Min and Max spindle speeds.
For example, if min speed was 0, and max spindle speed is 10,000, then for every VOLT output, the speed would increase 1000rpm
Does that make sense?
You will have to fine tune your drive and use something like a laser tach to check the actual spindle rpm. (Can be found on Amazon for less than $20)

Thanks Tom and Marty, your above posts have given me the info that I was not fully understanding.

Looks like I need to tune my spindle controller which I have not attempted at all. Now it makes sense.