Laser Not Turning off within a Letter

I’m trying to fill a basic arial font but the laser is not shutting off and filling the entire block. I know this works on this setup because a gcode file runs fine. Anyone know what I’m doing wrong? People have suggested turning off flood fill but that’s not available to my settings.
I have a Marlin setup with a on/off laser.

What does this mean, exactly? Do you not have PWM control at all? LightBurn uses all G1 moves for scans, only alternating the power between 0 and your fill setting, so if your laser is set up to need the M107 or M05 command to turn it off between every individual scan sent, that won’t work.

It appears that is what is happening. I have a Formbot Raptor2 with the factory supplied 1W laser add on. It comes with a rudimentary editor that generates gcode which seems to do fills correctly. But when I do multiple layered vector drawings, the laser does turn on and off between elements using Lightburn.

Also when I look at gcode file of a text fill attempt, I see constant M03 commands but no M05 commands? Seems like you are capable of turning the laser off and on. I see no other commands in the file that would vary the power. Only G1 moves.

M3 S0 sets the power to zero, and other M3 commands will set it to other power value. The GCode generator only uses G1 moves for fills.

It doesn’t matter as much on Marlin, but on other GCode systems, G0 is a rapid move, and if we used those for gaps the laser head would be constantly speeding up and slowing down, which can affect the quality of the output because of added vibration.

I see. My laser is not smart enough to do that. Maybe I can search and replace all the gcode M03 S0 state
ments with M05?

That could work. If your laser is only off/on anyway, you could probably just use the PWM output pin but always set the power to 100%, so it acted like a switch instead. That might save you some hassle.

I’m not sure what you mean. How would I do that? I’m talking to the printer and it’s turning the laser on and off. Don’t have a PWM pin.

PWM = fan output on Marlin firmware. It’s just an analog output, but if you only turn it on and off at full power, it acts like a switch.

Thanks. I’ll check with the manufacturer to see what this printers capabilities are.

I got a new laser that supports PWM and am now having even more problems:

  1. Laser fires at a higher power than what is set for layer when starting to scan causing blobs.
  2. Getting a scanning offset like condition but setting an offset does not seem to fix it.
  3. Now an M9 command is being sent (due to air assist I assume) which returns an error and the job stops. I don’t have air assist and this Marlin version doesn’t support it.


Can you find a version of Marlin that does allow the M9 command? I had no idea the support for this was optional, but it certainly follows the tradition of Marlin being the biggest pain in the @$$ I’ve ever dealt with. :slight_smile:

It’s like they’ve gone so far out of their way to make everything optional that it’s quite hard to come up with a feature set that you know will actually be supported. Points 1 and 2 sound like issues with Marlin itself - I’ve seen this happen before on some builds / forks of the firmware, but I don’t know what actually causes it.

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