K40 alignment. First time. Thank you in advance

I’ve been diligently researching and watching countless videos on the topic of CO2 laser K40 mirror alignment, but alas, I find myself still wrestling with some alignment issues. So, I’m turning to this forum once again, hoping that the collective wisdom here can shed some light on my situation.

Here’s the rundown:

  1. Machine Details: I’m dealing with a K40 laser, and I’m well aware that there are numerous variables at play.
  2. First Mirror Adjustment: When I push the gantry all the way toward the bulb, it seems I have to adjust the first mirror quite a bit just to get the laser beam to land on the second mirror. So far, so good.
  3. Gantry Movement: However, when I move the gantry all the way away from the laser tube (facing the machine), the laser beam veers off to the right—way off the mirror altogether. It’s as if the laser isn’t parallel to the gantry and is taking a sharp angle to the right…

Now, I’m no seasoned pro (yet!), but I firmly believe that we all start somewhere. :blush: So, I’m reaching out for any insights, tips, or potential pitfalls that might be lurking in the shadows. If you’ve encountered similar challenges or have a knack for unraveling laser mysteries, your help would be greatly appreciated!

And yes, I’ve noticed that most videos out there cover the basics but often skip over the nitty-gritty details. None that I have encountered have shared any of the potential pitfalls. :hammer_and_wrench:

Thank you in advance for your expertise and patience.

Have you seen this tool? (Can’t remember who I’ve mentioned it to…) It shines backwards from the nozzle with a visible red dot.

I did run into this product while searching the forum for a fix for my problem. Has anyone here used this thing. I would buy it if it worked and save me the frustration I am experiencing. :slight_smile: Anyone have a review for this item. Thank you for showing me this item.
Plus if anyone needs me to go into more detail on my situation just let me know what you need to know. :slight_smile:

I should point out I feel I am doing everything correctly so if anyone can share any factors on what can prevent alignment that would be helpful.
It seems the bulb is mounted correctly based on my measurements.
Thank you again. :slight_smile:

  1. Is this a new machine?
  2. Has it ever worked?
  3. How did the mirrors become so misaligned?

I’d suggest a video by Russ Sadler on alignment. It has adjustments yours doesn’t, but the concept is right.

Make sure you can mark the target on m2 (mirror 2) at maximum distance between it and m1.

  1. move m2 closest to m1, mark it
  2. move to the maximum distance from m1.
  3. mark a maximum distance should coincide with closest mark

Might have to do this a few times. When I first do the maximum distance I will just move the mirror, then mark, move the mirror, mark … I move the spot over with the mirror until it’s very close before I start sliding stuff back and forth.

I suggest you don’t burn a hole through the target… You’ll learn to read changes in things from these variation… light tough for a dark center → lighter outer rings.

A a general rule, most of these work, not always the greatest but are usually operable when you get them.

Good luck


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Hi and thank you, Just a quick response to answer your questions before I dive into your response.
1.Yes, It is a new machine.
2. it turns on and homes fine but I noticed that the mirrors were off on the test fire so I have not been able to engrave anything yet.
3. I feel the mirrors are misaligned from the beginning. I am sure I did not help when I started adjusting them being a novice although I was following a synopsis of the many videos I have watched. I have only messed with mirror #1 so far and the beam from the laser bulb seem to be hitting mirror #1 close to center. It seems when I try to bounce the laser onto mirror 2 I am able to align the beam into the center of mirror #2 but when I pull mirror #2 away from the bulb the laser is not traveling straight and takes a left angle from the laser beams perspective.

Thank you… I am going to study your response now.

The mark produced when m2 is closest to m1 is the target… You can only move this a minor amount.

Mark it at the closest point… then move it to the most distant and adjust m1 until it strikes the same location. Generally the close spot will not move much.

Make sense?



Thank you everyone. :slight_smile: So far I was able to use the technique offered with post it notes. I have the laser dots matching at the far end of the gantry. So the laser is aligned in that sense. The problem is, they are left of the 2nd mirror and I have the 2nd mirror nudged as far as I can by loosen the 2 screws that it is attached to and moved it as far left as possible. Any clue how to adjust the laser from this point in order for it to still maintain being aligned? I hope I explained myself well. If you need me to go into further detail just let me know. Thank you!

Ok, here is a video that might help you to help me. Let me know if you need anymore info. Much appreciated. :slight_smile:

I had a similar problem after installing a new laser tube. I see in your video you used a level to afirm the tube was level. I then used a level to see that the mirror1 was perpendicular to the tube (up and down) - now it fired through the hole in the frame - about in the center. Then I used the square that I aligned visually along the path from the center of mirror 1 to the center of mirror 2. and checked *with the square) to see that mirror2 was aligned with the frame and perpendicular to mirror1.
This put me close then I used the method in video

to finish the job. Good luck.

Thank you Walter! I will follow your lead. Thank you for the info. I ran into this video during my search on youtube and did find it very helpful. Thank you again!