Auxillary Control Outputs and Electronics Schematics

Hi, I’m a new owner of a Nomad 3 and I am wondering if there is documentation of the control board schematic anywhere. I’m curious about this for two reasons:

  1. I’m the type of person who likes to be able to fix things even when they’re no longer supported (long term)
  2. I’m wondering if there is a way of controlling some external devices using gcode through the board (eg a relay for a dust collector, a solenoid for an air blast etc.)

From reading through the forums, my guess is that there is not a direct way of doing this. In that case has anyone done something similar with add-on hardware?

There are labeled pins on the controller.

See the Grbl documentation for interacting with them.

Is this helpful?


For external device like spindle/router/vacuum, you’ll need a solid state relay rated for the current of your external device and triggered by 5v PWM output on the board. I searched “solid state relay 5v 220v” on my local, but you’ll find similar results if you search for your local electricity voltage on your local amazon.

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Thank you both for the replies. I opened up the back of the Nomad3 to have a look at the electronics and unsurprisingly the board schematic is a bit different for this new model. It does look as if there are still contact pads for the PWM, so as I get more time on the machine and am ready to add air blast capability it seems that will be my best bet. I had hoped for a relatively straightforward way of controlling air independently from the spindle so I could have it on for some jobs and off for others without manual intervention, but this will probably get me 80% of what I wanted. I’ve attached a couple photos of the Nomad3 control board in case any one is interested about what is back there, but doesn’t want to disassemble their machine.


Thanks for sharing. This looks very similar (maybe the same board actually) to the new Shapeoko Pro (some discussion and photos over here: Feed Hold Switch).

Looks like the spindle is controlled via a breakout board that uses the BitRunner connection on the board, that’s awesome to see this modular design.