Controller Drift?

I seem to be having a strange drifting issue with very large labels (This one is just over 1000mm)
It seems to be the engraving phase that causes things to go out of whack, if I do score, cut , engrave it seems to be ok. But not ideal. I do not think it is belt slipping as after the job is complete I can isolate parts of the job and they will be cut or engrave in the correct position. ( Am i correct in assuming if it was a belt slip it would be always out until a reset?) smaller labels have no such problem .

Any ideas?

A warning. Because you built the laser, you know what I’m about to describe cannot possibly be the problem.

Most likely, there’s a loose setscrew somewhere between the X axis motor shaft and the laser head. It’s supposed to be snug on a shaft flat, but when it’s a little bit loose it can stick at any position between two extremes depending on the history of forces applied up to that moment.

As long as it’s stuck, the laser will seem to work perfectly without losing its position. It will become unstuck only when the forces from motions exceed the stiction holding the shaft in place. Those forces are highest during vector motions, rather than engraving, so the vectors are most likely the part of the layout triggering the problem.

A previous discussion has pointers to track it down:

Good hunting …