Alignment question - how perfectly centered should the beam be in the cutting head?

Hey guys,

This is my first laser - I really appreciate the support here. I have things aligned pretty well in x,y,z - but the beam isn’t quite centered in the cutting head - I have the lens/nozzle removed and just firing down onto a piece of tape stuck to where the nozzle usually screws on.

I can modify the mirror bracket for the 2nd mirror to fix it (it’s already maxed out to the rear of the machine on the y-axis) - or maybe I can move the tube - I haven’t thought it through yet. I just wanted to ask you guys- in your experience will it be worth the effort to get it perfectly centered? The beam is about 1/16" towards the front of the machine. I attached a pic.


Measure the opening of your nozzle. It’s likely around 2 or 3 mm. If so, you’ll be already clipping the edge of the opening or close to doing so. And this assumes that the laser is coming down linearly in the tube. If it’s coming down at an angle then the problem is potentially worse.

I’d suggest as much as possible trying to get this dead center with as parallel of a beam as possible even if it’s a lot of fussing. Clipping the laser beam will dramatically reduce power and potentially damage your equipment. It can also cause other downstream issues not immediately apparent like issues with focusing.

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Thank you! I’ll work on getting this corrected.

Appreciated the information :+1:

Once your alignment is rock solid and the mark on the tape at the head is consistent in all 4 corners and the center, you need to be sure it exits the center of the nozzle. If your 3rd mirror is adjustable, simply adjust it so the beam exits the center of the nozzle. press a card against the end of the nozzle, them pulse the laser to see where it exits. If M3 is not adjustable and you need to tweak the beam, a small shim between M3 and the head will move the beam. Do not adjust M1 or M2 to tweak the beam!

I think you are in line here… the proper fix is to move m2 towards the rear… if I’m reading you correctly…

You will still be off a bit in the X axes… raising/lower the head, in the Z axes, will move the impact to the left or right depending on how your head is oriented.

What makes these work is the lens/focus … the beam itself is not of much use since it has no real power. The lens is what makes the machine work in a useful manner.

With a beam striking the lens off center, it will be slanted or not 90 deg to the table. Your cuts will not be square…

It’s possible for it to be off enough to strike the nozzle as @berainlb pointed out.

I want mine to be as centered as possible… you get to pick on your machine.

I have a jig for my machine to make this a more simple task… It’s just snug fit on the down tube.

Good luck