Hi, I hope this is the right place to pose this question. I have converted a chinese made laser engraver to run a plasma cutter. The machine mostly works but has a peculiar fault where the G code spindle start M3 and G4 dwell commands are executed in the reverse order. I have wired the spindle start (M3) output to a relay that starts the plasma cutter. The G4 dwell is normally about 1 second (depending on steel thickness) and is required to give the plasma cutter time to pierce the steel before starting the subsequent cut moves. That's the theory but what actually happens is the machine pauses/dwells, then starts the plasma cutter and immediately does the cut moves. Because it hasn't pierced the steel before moving it messes up the cuts. Here's the gcode I set up to figure out what was going on. You will see I have exaggerated the pause/dwell to 10 seconds so I had time to observe what was happening. This trial code assumes we are starting at X0 Y0. G90 G94 G17 G21 (Plasma cutting with GRBL.) M3 S1000 G4 P10.0 G1 X0 Y208 F1800 M5 M30 I'm using LaserGRBL v7.12.0 GRBL version is 1.1f which came loaded into the machine. I'm using Fusion 360 for CAD and CAM with the OpenBuilds Fusion360 Postprocessor installed to generate the Gcode files (although the sample here is hand edited to keep it simple for diagnosis) I found a work-around - if I insert G1 command(s) between M3 and G4 then it does the steps in the correct order. For example assuming we are starting at position X0 Y0 the code that works would look like this G90 G94 G17 G21 (Plasma cutting with GRBL.) M3 S1000 G1 X0 Y0.01 F400 G1 X0 Y0 G4 P10.0 G1 X0 Y208 F1800 M5 M30 Finding every M3 command in a big gcode file and inserting G1 commands is tedious to say the least. I tried putting in the M3 and G4 command sequence twice - it made no difference Can anyone suggest either how to fix the problem, or an easier work-around?
Problem solved by turning off laser mode. I very much appreciate your help and prompt response. I'm new to GRBL so didn't know this setting existed, and my search for the symptoms didn't find an answer. Thanks for your patience.
being new you should read the GRBL wiki, yep, all of it. it will give you background info so you know where to look for any furture things to adjust. Home knowledge is power! yes, I know we are now in the grblHAL world, and there is a wiki there too, but it is a bit more fragmented at this time and the old wiki gives a much better overview IMHO grblHAL each of the parts of it now have their own wiki, so we have to look under 'core' for the system then 'drivers' for the ESP32 details (ESP32 is in the Blackbox X32).
