Controlling JTech Laser and Spindle from PWM Pin

Will I run into any issues if I connect both the JTech laser and my Spindle to the PWM pin on the GRBL board? I read that there are two PWM pins on the board that do the same thing but not to short them. Would it be ok to hook the JTech to one set and the VFD to the other or hook both in parallel or do I need to setup a SPDT switch to change between VFD and laser control?

I asked J over at J-tech that exact question as I have the same setup.

J said that the signal into the laser module is optically isolated so the laser wouldn’t cause any issue. I’ll be testing out my setup over the next week to see what happens. Some of the parts I need to complete my build are due today.

I chose to keep a “manual” approach, of soldering a connector at the end of a pigtail from the controller, and connecting either the laser or the spindle at any given time. Yes, I know it’s not an answer to your question, just thought I would share. I did this to:

  • save me the trouble of any potential concern of plugging both (99.9% chances of it not being a problem anyway)
  • but mainly, to add yet another layer of security to my laser setup (no connection => no PWM => no laser). This is me being unreasonably paranoid, since the Jtech already has three barriers (key, on/off switch, and enable button if you wire it), but…why not.

This works for me because I don’t switch from one setup to the other very frequently.

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Just for peace of mind, I wired in a DPDT switch for the laser/IoT relay signal. I just mounted the switch on my panel next to my feed hold panic button.