That’s backlash, as shown in some of the circles earlier, and comes from loose screws / slack belts / floppy hardware between the motor and the laser head. It’s hard to find in large CO₂ machines and crops up everywhere in tabletop diode machines. 
You should start a separate thread for discussions on your machine so we can keep all the symptoms straight.
Can you put a photo of that here?
The last time you ran this backlash test your result looked reasonably OK.
Try this test, be sure to follow the instructions and turn of path optimisation and start the job with origin in the middle. It was made primarily to highlight potential problems with direction affecting the position of the start/stop points, but will show backlash also.
Backlash Test 56 circles.lbrn2 (44.6 KB)
So here’s what this test is doing to my machine. This is not an issue to me as I would never cut or engrave this fast. Changing the acceleration might help.
The wave occurs when the Y axis stops suddenly and then the X axis takes off in another direction. Shown in yellow. So as the carriage moves to the left as the Y axis is settling into position. The frequency of that wave is one natural frequency of that axis.
So the stepper is behaving as it should but entire Y axis is acting like a mass-spring system which causes this wave. I’m sure engineers designing these machines are well aware of this issue and do what they can to stay away from exciting a natural frequency
I’ve seen backlash on this machine. The Y axis stepper is attached to two rods that extend out to the pulleys. For some reason that connection loosens up so they start somewhere and the connection slips slightly and the beam comes around to a different location, creating a step. This is an easy problem to solve. I’m not seeing backlash
Whoops I was actually trying to talk to @BobR1 in my last post.
Dean, that’s not a good result, and you should not see this, because even if if you set the job to run at a ridiculously high speed in LightBurn, the controller should cap those figures to it’s own max settings which should be useable.
I’m not familiar with your controller, is it a rebranded Trocen? (this forum topic might help you).
