Grbl / SuperPID / Shapeoko 3

[crstophr]

Dropping this in here for the next person controlling a super PID v2 from grbl.

Code: Select all

#define SPINDLE_MIN_RPM 117.1875    // Min spindle RPM. This value is equal to (1/256) duty cycle on the PWM.

For the most accurate RPM control we need to use 117.1875 (30,000 / 256) as the min rpm. I believe PWM 0 is meant to represent off so the minimum RPM is PWM 1 or 1/256 of the max which in this case is 117.1875

The unfortunate reality of controlling the spindle this way is we only have 255 possible settings with each jump being about 117RPM. So no matter what value you send to grbl in terms of spindle RPM you will only get within about +/- 59RPM of the value you set.

I hope this helps the next person.

--Christopher

[atufs]

Figured most everything out.

[CastIrony]

The unfortunate reality of controlling the spindle this way is we only have 255 possible settings with each jump being about 117RPM. So no matter what value you send to grbl in terms of spindle RPM you will only get within about +/- 59RPM of the value you set.

Besides the aesthetic issue of setting 10,000 rpm and getting 9,945 on the readout, I don't really think this will affect your cuts significantly.

[JimInAshland]

I am new to the forum and all of this.
There are no recent posts about the SuperPID. Should I assume this is a mature topic? . . . I am milling plastics and the speed control on my DeWalt 611 is too limited.
Is the Super PID a recommended solution?
I see the Kress 1050 motor can handle the low speeds with power and precision but hard to find and needs 220V. The "chinese spindles" appear to lack confidence of reliable information.
Thanks in advance for any insight! Jim

[LTEPM]

You may want to check on the C3D community, there are some posts there on the Super PID. Which version of Control Board do you have?

[JimInAshland]

Thank You for the heads up . . . as a newbie I don't know the distinction between the "community" and "forum" venues.
My CarbideMotion grbl control board is version 2.4d

[WillAdams]

The forums are here, and are the original ones, dating back to the SO1. The community forums are new and specifically for Carbide 3D machines, so SO3/Nomad.

[JimInAshland]

Thanks for the clarification!