A relay cannot keep up with the electronics. To us it’s quick, as it was a hundred years ago. It’s still faster than us…
This is the typical output for PWM (laser) from a grbl board and came with my CNC3018.
I suspect you are making too big a deal about this and need to find the correct connections. From reading your posts, it fires on 12v applied to the power irregardless of the PWM input state. This may be your problem as it should not fire, if it is controlled by the PWM input and there isn’t any. If your documentation states this pin has a logical 1 for it to fire, you should be able to ground it and stop it from firing. If not, the laser has a hardware problem.
Some low cost lasers depend on the power to turn them off and on.
@Cortapalos showed the configuration and probably knows more about it than I.
Did you get that to work OK?
What kind of laser are you running, i.e. how much power does it require?
Do you have the documentation on your specific laser?
This should tell you about the PWM option.
The grbl board you are running must have a schematic somewhere… can you post it or a link?
Sounds like a combination of hardware and software configuration issues. Hang in there…
