View Full Version : A logical approach to mirror alignment. Easy and quick with no compromising.

Joseph Shawa
09-19-2016, 4:15 AM

Because of one very important thing I didn't pick up until today about aligning the mirrors I have spent several days aligning and realigning. Also, I believe that I have been suffering from misalignment for far for longer than I care to say. In fact, it was only by being out of alignment that I had been able to limp by. "Perfect alignment" in my case was not correct for my focus head.

I wrote down what I was doing so I would have rules to go by and not let anything slip. It worked so perfectly that I have to say that I cannot see but one burn mark from all four corners.

Everything has to get to Mirror 3 (M3) at the same height and centered horizontal in all corners of the table. What I didn't know what that the beam has to hit M3 about 4 mm higher than center to keep the beam centered in the cutter head tube and through the lens.This may vary depending on your head type. My beam has been coming down the far/right side of my focus head and getting chopped off by the cone tip because I was dead center on mirror 3. I have to say BAD DESIGN of the tube head.

Here is what I wrote down.

Tube level is Not important except to keep bubbles from forming if that is a problem in your tube. If this doesn't make sense or you don't agree I would love to discuss.

Measure distance from table or some reference plane to about 4 mm ABOVE center of M3.

Adjust brackets at M1 and M2 so the heights of center of M1 and M2 are the SAME height as center of M3+4mm. Any other heights and the beam will not be on axis. IT MUST FOLLOW THE AXES..
Adjust tube to hit M1 at proper height. Test fire at tape or target of your choice. I find that tape doesn't get on my mirrors as they are recessed and they are easy to clean anyway.

M1 should be turned 45 deg. so it can reflect beam parallel to Y axis. Rotate mount to get it close THEN use mirror adj. screws. Don't try for the center of the mirror yet! Adjust M1 so beam hits the target while at (0,0) and (0,Max) in exactly the same spot on the tape. You are on axis now. Don't adjust M1 any more!

If you are not hitting the center of M2 then move the whole assembly. Don't adjust M1 to do this or the beam will be off axis.

You can measure your height again from the deck at M2 if you want but it should be at the height it was when it left M1 because you are still on axis.

Once M2 is in the axis the gantry will move M2 on this axis/ beam line and strike the mirror in the same spot the whole way.

The exact centering of the beam on M2 is not critical. The beam doesn't know if it is exactly in the center of the mirror. Just don't lose part of it off the mirror's edge.

At this point I would like to say that the MOUNTS should be easily adjustable in 2 dimensions X,Y plus Z separately. At least at M2.

M2 to M3 should now be hitting the same spot on the target at ALL table locations. Use mirror to bring beam height to center of M3+4mm and center horizontally..


Shoot through the head onto a target. A piece of tape pressed hard on the end of the cone works but make sure your blower is on so it doesn't smoke up your lens.
Adjust the M3 screws to center the beam.out the cone. If it is too far off center to the left you might want to increase to M3+5mm. or M3+3mm if it is too far to the right.

Bill George
09-19-2016, 8:01 AM
Since it is a Chinese machine you just may just have to put up with the constant re-alignment and adjustment. Quality varies greatly from one brand to the next and even one machine to the next. You generally get what you pay for.

Joseph Shawa
09-19-2016, 9:28 AM
Chinese or not, I cannot see a reason for it to come out of alignment if the bolts are tight. It isn't made from thin aluminum. The main alignment problem has been that if alignment is spot on the middle of mirror 3 then the beam gets chopped of at the cone. Apparently this is a normal feature? And I missed it. But I got dang good at alignment :-)
Interestingly I learned the fix from rabbit. Are they Chinese?

Bill George
09-19-2016, 9:40 AM
Interesting, I had a Chinese machine and it worked fine but I was always messing the alignment. Purchased my 10 year old ULS, brought it home in a U Haul trailer. Plugged it in and the only thing I have done to it since over a year and half ago is clean the lens and vacuum the inside.

Jerome Stanek
09-19-2016, 9:56 AM
My Chinese laser has been running fine for 3years once I got it aligned even when I change my lens.

Bert Kemp
09-19-2016, 10:56 AM
Mine was hauled from Ohio to AZ in the open back of a P/U for 3 days hauled up some stairs and set up and has been running for 2 years , I never aligned it, just clean and oil.

Dave Sheldrake
09-20-2016, 8:32 AM
The 4mm offset only applies to HX Made machines