Laser fires using fire button but not during cut

What could cause the the laser to fire using the fire button but with the same power setting it doesn’t fire when started (iE starting a cut / engrave). I can see the PWM pulses on a oscope and there exactly the same amplitude and width if using fire button on the move screen or running from start.
It acts like a hardware issue but I can’t seem to be able to track it down. Yes the Output and show are both on. I noticed that this dose not seem to be all the time but intermittent. Resetting the controller and / or restarting lightburn sometimes fixes it.
This may or may not be related but in device settings on the additional settings tab if I read from controller i get 16.7 for x and y mm/sec> where does that come from? It’s not in any of my GRBL settings. BTW I’m using GRBL 1.1 - LPC for 32 bit controller.


16.6667 * 60 is 1000, so it’s in your $ settings as 1000 mm/minute, not 16.6667 mm/sec.

If you try to go faster than that, GRBL will reduce the output power, but that would show up differently on a scope. I would check to see if you have any odd grounding or wiring issues. If it behaves differently when moving or not, it could be related to the power draw from the steppers, but that seems less likely.

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