Hi guys
Just making some signs on acrylic and for some reason the start and finish don’t match up. Its happened before with the belts needing tightening. I’ve checked them. Can anyone suggest anything else to check please?.
Many thanks
Rich
Check if you get any help here:
There are many many other things to check when looking for backlash:
- Bad factory assembly
- Loose focus lens or mirrors
- Loose screws anywhere
With the power off, push the laser head by hand to feel for loose motion, then track it down and fix it.
Also, turn off LightBurn’s Hide Backlash switch and make sure the controller’s Backlash settings are zero. The only way to fix mechanical backlash is to fix it, but it’s also possible to have the software introduce backlash by “hiding” it when there’s nothing to hide. 
Fixing the backlash may also cure the ragged engraving edges, but if not you should measure and set the Scanning Offset Adjustment table:
Good hunting!
Awesome thank you. I’m working on the offset. It’s loads better than it was but still needs some work. I had issues previously where the head didn’t stop and after a while the rubber from the belts had built up on the teeth causing it to skip. Craft knife and some picking sorted that.
Also I’ve been trying to find out why when you have the red dot at where you want to begin you press the frame button but the frame is say 1 or 2 mm bigger. Is this just a safety net or something in settings?
If that’s the case, that puppy is in need of new belts.
It’s entirely likely the dot is not positioned exactly at the point where the laser beam hits the material, because it depends critically on the proper focus height and the stability of the craptastic red-dot holder.
Do your usual focus dance on some scrap cardboard, then fire a manual pulse. I expect the red dot will be within a few millimeters of the hole, in which case you must twiddle the dot until it’s at the right spot.
Some tweaks on my machine may suggest improvements for yours: