Need help with laser alignment

[Anze Mulec]

Hi all,

i am having trouble with aligning laser beam on a 130x90cm 120W chinese laser. It seems like when laser head is close to me in front it is centered, but more it goes to back of the machine it is pulled diagonally up and right. I made 9 different measurements in different parts of machine.

LR= Left Rear
LC= Left Center
LF= Left Front

CR= Center Rear
CC= Center Center
CF= Center Front

RR= Right Rear
RC= Right Center
RF= Right Front

I am attaching image of targets and where the beam is hitting. I dont know which part of the machine needs to be adjusted at this moment, 1st, 2nd mirror or perhaps tube angle?

And thing is laser is centered on 2nd mirror at all distances...


IMG_20180204_163355.jpg

[Kev Williams]

looks to me like you need to move the first mirror CCW a smidge, to counteract the beam moving right, and down a smidge to counteract the beam moving up.

--a 'smidge' is roughly equal to half a 'hair' -a little goes a long way...

[Rich Harman]

Tube angle is irrelevant. As long as the beam hits the center of the first mirror, the first mirror can steer the beam where it needs to go.

It looks like your first mirror needs to be adjusted. You need to get the first mirror dialed in before moving on to the second and third mirror.

If the first mirror is adjusted correctly and you still have the spot moving up and down when the gantry is moved back and forth, then your Y rails are not lying on the same plane.

If the first mirror is adjusted correctly and you still have the spot moving left and right when the gantry is moved back and forth, then your X axis may be askew. Could be a stretched belt, uneven belt tension or something slipping.

[Ian Stewart-Koster]

I found that exact issue- the Y rails were not in the same plane.
It was an easy fix- the floor was not quite level. I put a packer under the foot of the laser on the ground at the lowest corner, bringing them back to being planar. No mirror adjustment needed in our case.