How to adjust laser path when everything is already coplanar

I have aligned M1 to M2, and M2 to M3 paths at all corners of the bed. The issue now is that the entrance into M3 is slighly high and left.

It doesn’t appear that there are adjustments that can be made to move the laser head assembly that includes M3. That would have made things easy.

I see I can adjust the M2 mount in the Y direction by loosening and sliding the mount in the desired direction.

Anyone have advice on how to get a better aligned entrance into M3 ?

Thank you

Depending how M3 is mounted you may be able to shim your way to the adjustments.

If not, you may need to work your way backward to adjust farther upstream. Ideally the tube and all mirrors would be coplanar. That will solve the height issue. The lateral adjustment you should be able to solve by extending M2 outward toward the front of the machine.

Photos of your machine may provide additional insight.

Many of us have replaced some of these parts to facilitate alignment…

If you have the standard head, ensure the center of the hole is the center of the mirror… This is my original head, you can see the hole is offset to allow for the screw adjustments…

It’s not a crime if it doesn’t hit m3 perfectly, at this point in the alignment it’s more important that it’s going down the center of the lens tube and hitting the lens at its center…

If the beam hits the lens off center it will come out at an angle (like it went in)… either hitting the nozzle or giving you a cut that is not 90॰ or perpendicular to the table.

Have/can you checked it from m3 down to the center of the tube/lens and table ?