Centroid Community CNC Support Forum

In tech bulletin 267, the table on the first page implies that you could operate with a lower number of counts/rev to increase the maximum motor speed. However, it's not entirely clear to me how/if this is achieved.

I assume that you would change the electronic gear ratio in SigmaWin+ and the encoder counts per inch value in CNC 12, but I get the feeling there's more to it than that (aside from potentially tuning again).

The electronic gear ratio and encoder counts per turn in CNC12 are it.

There should be no adjustment of either. The drive is handling the motor control with a million counts (20 bits) per revolution in either case.

So it cannot be operated at a lower resolution and I'm stuck at 2197 RPM max?

irishismyname wrote: ↑Tue Sep 17, 2019 11:34 am So it cannot be operated at a lower resolution and I'm stuck at 2197 RPM max?

Sorry, I meant to type that you shouldn't have to re-tune because the counts/rev in the drive didn't change.

The counts/rev sent to and from the control can be changed as described in the tech bulletin.

Right.
All you have to do is change the numbers in both the sigma drive and cnc12, as the bulletin describes.

You don't have to change anything about the tuning

In particular, the part where it says:

"You will then need to enter the gear ratio. Enter 1048576 on top and 32768 on bottom"

enter the counts per revolution you want instead of 32768

Use the same number in CNC12.

(and ensure you follow the rest of the steps in the sigma drive, particularly, applying the new output encoder count, or else you will get wrong results - the drive will move the wrong distance per revolution and not move at the commanded feed rate)

Thanks for the clarification guys, got it moving at 4394 RPM with 16,384 cts/rev now.