Strange Alignment Issue

This morning I tightened the belt for the laser head rail, I never remember if its X or Y. I actually removed the gantry and made sure it was square then tightened and cleaned everything.

After putting it back together I cut some Christmas decorations (always be prepared), made a few boxes for the bits I keep around the laser and then a few card trays. Everything cut perfectly and was all great, however, I then thought I should make a start on a little project for my wife’s Nan.

I have attached a picture of the file in light burn and a picture of the result in the laser, can anyone explain what has happened to the alignments and more importantly, where I start when it comes to sorting it out?

The weird thing is, the last heart that was cut, the sideways one on the right-hand side of the image, was the only one that was aligned as it should.

Any help much appreciated and thanks for looking.

The sideways one is also off but because you lost some steps along the X axis the hanging hole and the points are still lined up.

Most likely the belt is either too tight and causing added friction in the motor or the motor bearings are worn and have more friction when moving fast and the tighter belt exacerbated that.

Thank you dougl,
I will check that in the morning as I may have overtightened the belt. Somewhere else I was told it should hum but not knowing which note it should hum when plucked I went until I liked the note and the laser head still moved easily, perhaps it was still a little tight.
Thanks again.

I had overtightened the belt, I then went the other way but a little perseverance and I was able to get dialled in. Thanks for the help.


What I do is move the laser head or x axis back and forth to watch the belt at the motor gear looking for any sag or flexing at entry/exit sides of the motor gear. When I see even a slight flexing/movement I only slightly tighten the belt more and test again. Having the laser head or axis furthest from the motor gear as you move it back and forth exposes the most flexing at the motor gear.

Too tight can cause problems just as too lose can cause other problems. Getting it ‘just right’ takes a bit of effort but not much.

1 Like

You also might be hearing the end of life for the stepper motor bearings. They are easy to replace as shown in this video but getting the drive gear off does take a lighter or propane torch to heat the gear and cause it to expand so the motor shaft can be knocked out of it.