Check Size doesn't turn the laser on

Hi All,

I am using LW and for all its faults think its the best bit of laser software available. I do have an issue though.

When I run the check size, LW doesn’t turn the laser on. I have it set correctly in the settings and Laser Test works just fine so I don’t know what I am missing.

Linux version laserweb-builder-v4.0.996-130-x86_64.AppImage on Arch
GRBL 1.1f
Diode laser

Any help would be great

You might add which laser type you have, CO2 or Diode or ?.

Using a diode laser

so digging around I found the code that is generated when clicking on the Check Size button:


        G0 X5e-324 Y5e-324 F1800

        G1 F1800 S10

        G1 X1.7976931348623157e+308 Y5e-324

        G1 X1.7976931348623157e+308 Y1.7976931348623157e+308

        G1 X5e-324 Y1.7976931348623157e+308

        G1 X5e-324 Y5e-324


I was just wondering if it shouldn’t be something more like:

G0 X[left] Y[bottom]
G1 X[right]
G1 Y[top]
G1 X[left]
G1 Y[bottom]
G0 X0 Y0 F500

If LaserWeb has a feature which turns on the Diode laser at low power for visual framing then ya, that’s more like what should be expected. But, are you sure LaserWeb has that feature? Many CO2 laser machines have a red dot laser specifically for alignment so you would not want to turn on any power to the CO2 laser during framing. LightBurn has a special setting specifically for diode laser framing because you do not want to do this with CO2 lasers.

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If you look at the above code, it shows a power setting of S10. However it seems like it is not in the right place to trigger the laser or at least a diode laser anyway.

I see that now and IIRC that should turn the laser on after the M3 command.
M3 and M4 turn the spindle(PWM/Laser) on and M5 turns it off. I don’t see M3 nor M5 in that GCode.

For any one else looking for an answer to this, use the Laser Test (set to 0 in duration settings) and then click on the Check Size button

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The laser is not activated automatically because this would be a security issue with CO2 lasers.
The solution is to configure the “TOOL TEST POWER” in the gcode settings and use the “Laser Test” button to switch the laser on before “Check size” and off afterwards.

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