Laser Cutter

[ABearden]

Got everything hooked up, but apparently the power supply on this thing is active low. Instead of trying to reverse all of the M3, M5, and S my first thought was to add a hardware inverter. I rigged up a 741 OpAmp and what do you know they really don't like operating as an inverter on 4 (despite minimum power being 3V). Then I tried to remember my EE classes from college and rig up a single-transistor as an analog inverter. Given the random collection of unmarked transistors I had laying around, that didn't go well either. See what 10 years of mostly forgetting EE math gets you?

When hardware fails you, implement in software! Took about an hour to trace the GRBL code down to the specific portions controlling the spindle. Added a macro to enable a secondary code path that inverts all of the PWM output logic when defined. Poof, laser works as intended with M3, M5, and S codes all working normally. Once I'm allowed to make noise (shop vacs at 1am make for very angry neighbors), I'll fit the Arduino back into the CNC table and fire it up!

Going with a heavy wood cut surface for now due to cost and availability, but at some point I need to switch over to expanded aluminum. So much nicer.