When cutting a circle, or any shape really, I get a black dot where the cut starts and ends on. Hide backlash is turned on. I have the most recent version of lightburn. Start time, end time and overcut are all set to zero (maybe I wish a negative number could be put here) There is no lead in or lead out.
How can I fix this? I know there is a x-axis backlash setting I can change in the machine settings. Should I change this?
I assume that it is reasonably thick material, the black mark is reminiscent of the initial splatter that we see when cutting metal, just before the laser penetrates through the material. Have you tried with lead in?, could be interesting and see if it helps.
Opinion: When a machine has enough mechanical backlash to produce a visible error, the only solution is to find and eliminate the mechanical problem.
The software and firmware can try to push the backlash somewhere you won’t notice it, but circles have nowhere to hide the problem. Worse, if it’s successfully hidden in this design, it’s just waiting to ruin your day in the next design.
On a big CO₂ laser, Y axis backlash most likely comes from a loose setscrew in a couplers on the jackshaft across the machine or in the pulleys driving the belts. Some folks have found stripped screws in the laser head, to the extent the whole thing was finger-loose on the X axis carrier.
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