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Is there a trick to PWM?

Posted: Thu May 28, 2020 6:19 pm
by KevinPartner
tl;dr I can't get M3 S1000 to work in laser mode

I've been slowly building my CNC, making sure each stage works before I move onto the next, but I'm currently stuck trying to get my laser to work. Testing with a multimeter, running M3 S1000 and measuring V across Spindle Enable and Gnd reads 0V. I have tried a manner of combinations of M3,M4, and M5 as well as various S values. I've been able to get the laser to power on (see below), however M3 S(Anything) does nothing when sent by the UGS or by Arduino Serial.

I'm sure the laser is wired correctly because when I connect the PWM input for the laser to the Coolant plug and try M8/M9 the laser turns on with full power.

Pertinent Settings:
$30 = 255 (also tried 1000)
$32 = 1

Thanks for the help and for reading!

Re: Is there a trick to PWM?

Posted: Wed Jun 03, 2020 7:23 pm
by Bertus Kruger
This is a short guide on PWM with GRBL...

https://blog.protoneer.co.nz/grbls-pwm- ... d-spindle/

What kind of laser driver are you using? is it using PWM 0-5V?

Re: Is there a trick to PWM?

Posted: Fri Oct 16, 2020 6:18 pm
by anewsome
Once you enable "laser mode" with $32=1, the laser will refuse to come on if the there is no movement.

Once you enable $32=1 laser mode, your laser needs to be moving in order to fire. If you want to turn on the laser with no movement, do $32=0 first.