MakerFr.com

Hi there.
I am doing a mash up of the Root CNC mechanical build with the RS-CNC32 electrical side as it seemed the electronics where better documented with your setup. I have your V1.5 board.
I read that your GRBL32 board could manage 4 axis, and I had read elsewhere that GRBL can duplicate an axis onto the "a" pins. So i assumed (possibly incorrectly) that I could run 4 motors on 3 axis.
I have 2 motors running ballscrews on the Y axis.
I had planned to just run and split the wiring from the Y axis step dir pins to 2 different drivers and then connect those to the two motors.
As i near completion of my build though. I have realized that this will work fine for running any GCode, but it wont really work for the homing if the y axis is not square. Even if i I have 2 limit switches wired up, it'll just stop both motors whenever either one is triggered.
Is there a way to duplicate the Y axis onto the A pins in the software??

Thanks in advance.
Iain

Hi Iain,

iainforrest a écrit : ↑30 mai 2021 05:21 Is there a way to duplicate the Y axis onto the A pins in the software??

Considering the numerous posts from mstrens and Romain (RoMaker) about this possibility, I am afraid it is not possible with the firmware of the v.1.5 Grbl boards.
You can of course use 2 motors for your Y-axis, but if I understood well, you will not be able to make an automatic square of your Y axis, even if you had a second endstop on the other side of your Y-axis. You will have to perform a manual square of the Y-axis every time you should mill a part.
In the other hand, this function (automatic square) is available in the firmware of the Grbl boards v.2.0.

I let mstrens and/or Romain complete my reply.

See ya,

I think that GRBL version running on arduino UNO (perhaps Mega too) support duplication of Y axis. Then it should work the way you expected.
I am afraid that the STM32 version of GRBL (used in RS-CNC32 V1) does not support this function.

V2 is using a version of GRBL running on an ESP32 and it has a special implementation that allows you to use:
- an extra driver (says Y2)
- 2 end stops for Y (or other axis) connected to the same pin
- just one extra DIR pin connected to the Y2 driver.
- uses just one pin for STEP on Y and Y2 driver.
During normal operation, it duplicates DIR on DIR2
During homing the program performs special handling with to square the cnc.
So this version of GRBL does not even need the full 4 axes.

OK.
Thanks for that. I'll look into upgrading to your V2 or getting a Uno with shield.

Cheers,
Iain