Gantry issues pushing focus out at the top of the laser bed?

Hi Guys

I am unable to get my Mirror 2 to Mirror 3 properly aligned when going from top left (furthest away from me) to top right as the second pulse when at the top right pulses below the first?

When I move the laser head down closest to me and repeat the process the alignment is spot on (as in both pulse is on top of the other).

What can cause this?

I have tried propping up either rail to aim the beam up but it don’t seem to make a difference.

I also have a new tube fitted.

Mirror 1 to Mirror 2 are pulsing on top of each other.

Looks like a “fourth corner” problem, as discussed elsewhere:

The general procedure is to get the beam aligned & centered on both Mirror 1 and Mirror 2. Then you align & center at the entry to Mirror 3 with the gantry at the rear of the platform, which will inevitably mean it’s not quite right with the gantry at the front of the platform.

If so, then:

  • Mark the entry to Mirror 3 with the laser head in the left front corner
  • Move the head to the right front
  • Adjust the Mirror 1 vertical screw in very very very tiny increments to move the right-front spot so it overlays the left-front spot

The Mirror 1 vertical tweak will be tiny, so be careful!

My experience may be helpful:

Tiny tweaks! :grin:

Thank you so much for your help.

So I’ve done this and now it’s perfect.

The only issue is from M1 to M2 it is slightly out.

If I align this will it throw everything back out? Or do I just leave it as is.

The tweak is to correct m1, so it’s a micro amount of movement… if you throw the others out of alignment, you’re moving it too much.


The whole mirror alignment process is iterative, so you get to decide when you’ve had enough fun. :grin:

The visible part of the spot just represents where the beam has enough energy to damage the target, so keeping it close to the center means all the energy you can’t see gets to where it will do the most good.

So, AFAICT, as long as the spot is pretty much centered on all the mirrors and remains that way all across the platform, it should work just fine.

Fire The Laser!


Thank you both for your help. I was really lost here. I also watched Russes video which may highlight an issue at mirror 2 I just couldn’t figure it out.

I managed to get it almost bang on centre and did a test engrave and cut.

I was able to half the power I was using (previously 60 to 30%) which is amazing.

I hadn’t thought to just slightly tweak M1 to get it closer. I guess as long as it’s even throughout each corner that’s all that matters and then obviously get the z axis perfect.

I owe you guys some beers.

Glad you figured it out…

Have fun