Z-axis disabled but moving at start and end of print

LightBurn Software Questions
1

Just getting started with Lightburn and my BIBO 3dPrinter using a laser diode. I set the laser focus at 30mm manually then start the engraving gcode, after homing just x and y the z-axis moves down 10-15mm. This z-axis movement occurs again twice at the end of the print. I’ve looked for settings (z axis is disabled) and I’ve looked at the gcode and I don’t see any movements. I had trialed inkscape with jtechphotonics plugin and did not have this issue. What am I overlooking?

2

If you do not see any Zaxis motion commands in the GCode, it has to be something going on in your controller.

Create some very simple programs and see if you can find one where the Zaxis does not move. You might also upload a simple GCode listing here that does make the problem appear. There might be something strange in one of the lines of code. More eyes on it is good for success.

Another thing to try, using your GCode listing for reference, is enter the commands one at a time in the Console window. See if that triggers the Zaxis travel.

3

I think it has something to do with G90 commands.
I added a g90 command and the z-axis moved more.

current Workaround

  1. reinstalled the printer’s BLTouch
  2. Home the printer
  3. move to 40mm and focus the laser
  4. added a G1 Z40 F2400.0; to the custom start gcode to move things back to the focus position when the printer moves when it shouldn’t

still odd as this z-axis movement does not occur when 3D printing or when using inkscape+jtechphotonics plugin

Here is a link to a gist with the contents of one of the files which does not work right and the printer moves

4

This points to the controller software being the issue. A G90 commend should initiate no motion travel. I simply tells the controller to switch to Absolute Coordinates. It does not matter if it follows a G91 or another G90.

Can you capture the GCode when using inkscape+jtechphotonics plugin? If so, you could try to find a difference that might explain what is happening.

5

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