Specific Patterns/Lines Skipping

K40, C3D, Lightburn, Win10
This might be kinda hard to explain. I have certain patterns that will skip, a lot. It happens when moving from one line to another. Never the exact same spot but close. When it moves to the next location it seems to slam hard to that spot. I’ve had a small amount of success by moving the part. I don’t think it’s a hardware issue, This only happens with a few of my patterns. Only on lines (vector), never on fill. Kept under 35mm/s. One pattern it only happens where I used the draw function and manually added lines. The reason I’m thinking it may be software is the predictability of when it will happen, or close to it. Belts are not loose and have no worn spots/missing teeth.

This sounds more like how it was build or is being generated by lightburn. It would help if you post the .lbrn2 file for us to examine.

If you slow down the ‘preview’ can you see what it’s doing?


I’ve gone through the preview, nothing stands out. It happens in the same area each time but not the exact same spot.
And are you asking me to post my patterns?

Here’s an example. When moving from the part on the right it slammed to the left and skipped. But it’s not the exact spot each time. I drew where the next cut should have been.

That sounds like your ‘default_seek_rate’ setting in the config file is too high, or your acceleration is too high. When doing a cut or engrave, the speed of movement is based on the speed of your cut setting. When moving between cuts, the movement speed is taken from the default_seek_rate setting in the config file. If that (or the acceleration) is too fast for your hardware, it could skip.

There are a few different ways to counter this:

  • Lower the seek rate setting
  • Lower the acceleration setting
  • Increase the ‘current’ setting for the axis that is skipping, so the motor has more torque

Any of those individually, or in combination, will help.

I found the acceleration setting under device settings. I’m guessing the other setting are found on the SD card on the controller?

There is no acceleration setting that affects your controller in the device settings. You’re likely looking at this page, and ignoring the bright red text at the top:


All of the settings you would need to adjust are in the config.txt file on the SD card in the controller.

Found the seek rate setting. Changed it from 24000 to 20000.
I’ve run one of the troubled patterns twice with no skips. Machine even sounds better now. Before it tended to sound like it was shaking itself apart.
Thanks everyone

This topic was automatically closed 30 days after the last reply. New replies are no longer allowed.