Laser Mirror alighment goes wrong

Hi folks.

So today , a realize that when i last time try to make right angle on right rail and the , head , rail . the right belt was probably one toth on belt running .

After this alighment i try my mirror alighment …of course i make an mistake and do it only in middle of workplace :slight_smile: so there ist was OKAY. i try to finis One order . one Family calentad with was 480x220 mm first the all engravings , nothing wrong on engraving and when ist starts CUT a noticed Double cuts on right side .

After checking the alighments the pulse on paper was barely on the corner .
So i start to alighnt all mirros from 1,2,3,4, every corner . the right way . after few hours of trying be on center i do it.

starting againv with calendar order aaand i try to make some test cuts before .

Test cuts are not good . The power and feed that i use for 6mm plywood were 15mms and 40% power from 80w tube . cutted milion times before withou any problem . and now barely 3 mm deep cut only .
so i gues somewhere is my laser beam power loses.

Bud why ? Where ? what should i check ? Mirrors are alight and clean , the focal lense is clean , the focal lenght is same as before

Do you have a picture from your M1 test shot?

No, i will go find some test and do it .

Lower the power or pulse duration. We want a lightly brown spot, not a black or burnt out spot.

When you do an alignment, you have to start with a good beam that is resonating in TEM0 mode or it’s not going to perform. So start at m1 (mirror1) and check center of mirror and the mark itself for a good beam.

On the head shot, are you sure the center of the hole is the center of the mirror?

Mine wasn’t…

Good luck


okay… wel i check it again woth lower power . an ist seem to not that alighnt that i think first time :confused: … whoole day its gone and it was not even good :smiley:

Mirror one , and mirror 2 nice dot pulse is close to mirror 1 second big pulse from down left corner .

thanks , i have no idea there are few types of beams . i go check it and give a feed back :slight_smile:

Me thinks your tube has had it…

I don’t follow what you are saying here… Neither of the marks on the tape look acceptable.

Is the 2nd photo from m1?

A setup similar to this…

Mine failed, this is out of TEM0 resonance… It is not round and the power is not in a Gaussian distribution. It did move from center when the mode changed.

A Gaussian distribution looks something like this…


It burn mark should be dark in the center and get lighter as it goes outward.


Sorry, but I wouldn’t accept this alignment either if it was my machine. And, as @jkwilborn writes, this circle in M1 doesn’t look too good. Anyway, I will try to center the test shots straight from M1 to M3 and then check if the nozzle is at a perfect 90 degree angle in both directions.

I hope you succeed in getting an acceptable align result, then you have to look at the tube itself afterwards to see if it has an error and cannot present as it should.

I aligned mine with it out of TEM0, was more difficult to accomplish, but you could get to to burn…

I had to remove the cutting nozzle and use the engraving nozzle for the beam to clear the nozzle. So the beam shifts, as can be seen in the photograph.

Once I knew mine was toast, I aligned it best I could, then proceeded to abused it even more by cutting some thick acrylic… The sides were not square, but they worked for the intended purpose.

What I’m trying to say, is it could sort of work, but it isn’t right and won’t perform if the tube isn’t in TEM0 mode…

So check the beam first, instead of wasting your time trying to align something that, at best, will work poorly…

Good luck


If it was me and I have to deliver some production, I will give it a chance, what can go wrong?, if he doesn’t try, he can’t do anything at all.

The production run will be sub quality… Is that what you advocate?

Just wanted to mention, if the input source is bad so will be the output result.

Usually applied to computers, but is equally applied here garbage in/garbage out…


I’m not that qualified to send the man out for a new tube and certainly not on the basis of one or two pictures that I don’t know under what conditions and with what settings they were made. That’s why I recommended trying at least to get a usable align result. What will go wrong?
It wasn’t the tube’s effect or focus that was the original problem, if I’ve read correctly. So if the machine was running satisfactorily before @Steam worked with the belt, then the chance that the laser will run again (at least as before) is high.

I wasn’t sending a man out to replace a tube, just advising he check the tube before wasting time trying to align it, again. Hopefully, at least, realizing it won’t be up to spec if it does align.

A proper alignment should include a mode test, so I’m not asking for anything out of the ordinary…

You should always do alignments from the beginning, which is the tube. First, checking where it hits m1. You can easily do both in one shot.

You only have to look at it, thinking mode instead of position.


Thanks for very educative advices , after work I will try it from beginning with proper pulse photos from mirror 1.

I have no problems since I have this machine , there is an efr f2 tube and it should be maybe on 30% of his lifetime . And before my ,belt, alignment I have no problems with cutting or engraving , only thing was problem when I cut circles around 400mm plus the roundness was not good , that’s why I start looking for angles on rails and find out that 1 tooth on belt was bounced . Probably it was from the production because the mirrors were alignment to this state.

Here is how looks my calendar before any mirror alignment , this was only the right side of piece, the left was normal , great cuts as before .

Don’t jump into replacing the tube… Do the proper alignment, if the tube is going south, you can see it on the output…

Time used doesn’t really seem to matter too much… Most of these tubes seem to be grade B tubes and there is no telling what their lifespan will be.

A good tube should last about 10k hours or about 5 years of commercial use… If it sits, it degrades also, so you don’t want a tube made a couple of years ago.

Do a proper procedure on the alignment.

If you have

  1. working tube
  2. clean and aligned optical path
  3. focus

The machine will work…

Good luck.

Guys. Here are photos from first mirror… in this point I’m not really sure if this beam is okay…


I would say, no… sorry… I’ve felt the pain of a tube in the throws of death…

Suggest you find a replacement… I ordered my last tube from Cloud Ray…

This is what I was seeing in the first few photos you posted… this is why I brought it up…

It’s obviously a doughnut shape. The center could be described as untouched, where you’d would expect the most power to be.

As was suggested, you can get what you can out of it… but it will never have any kind of good beam quality.

The parts I did with mine when it was failing was ok, functionally, not visually, nothing I’d give to anyone else…


im really angry now, or its sadness. dont know at this point

I suspect … both… I was bummed when I noticed it was going out of TEM0…

It’s a consumable… and it’s apparently consumed… time to move on…

They make nice decorations for the wall… Mine old one is on the shelf with other tubes, mostly radio stuff…

Hang in there… :face_with_spiral_eyes: