what would you do in the next step.
pictures are attached.
Would you be happy with this?
the burn mark looks a little different in picture 3 which is on the bottom right. Here the laser is clearly weaker than in the other places, why?
I feel quite happy with the alignment otherwise and I get a good hit on the 3rd mirror. the laser beam passes out of the laser head without any problems.
the mirrors and the lens are clean. I’m working with a laser that has a working area of 1400x900.
the red dots in the pictures are markings at focus and the larger marks are burned at 70 mm
Interesting approach but I’m not sure what an out of focus burn means. I have a nose cone that directs air to the cut. I just rub tape into the opening (smash into end leaving a ring on the tape) and note where the beam hits the tape over the bed range.
This tells you how well the mirrors are aligned but not if the beam is 90 degrees to the table.
Your M2 is probably not quite in the center either, which then passes the deviation to M3.
It’s up to you if you are otherwise satisfied with your machine performance and the laser beam does not hit the inside of the nozzle (no. 3 could indicate that you are close…)
If your nozzle is guaranteed to be perpendicular to the machine bed, i.e. the fault does not lie here, then I will try to check and if necessary, adjust everything from scratch.
A little hint, you can buy or make a target holder that fits nicely in the opening in front of the mirrors, for Z there is also a similar tool. With such tools there is no room for guesswork anymore.
I have removed the copper wire, it is not necessary - in fact the opposite. The part to control Z with has a hole in the middle but works the same way, the targets themselves I made myself.
If you have taken 2 shots with e.g. 100 mm difference in height, and you get the result that you show, then your laser beam is not 90 degrees. But, maybe I have not understood your problem correctly.
If you have centered your M3 so that you get a nice little hole in the middle of the tape that you put under the nozzle, then there should be no deviation in center no matter how much you change the focus.
That is exactly the problem here. But I have only lowered the table 70 mm. If I lower it all the way down to 130, the results will be even worse. I simply have to make my alignment better, even though I thought I got it right.
And the fact that the beam is clearly weaker in the right lower corner is also of course a problem that needs to be addressed.
It is “normal” to lose some power on such a relatively large machine bed, therefore it is even more important that the alignment is perfect.
Sometimes it can be annoying and other times it goes very well and quickly, I personally am the type who wants it perfect, but my bed is only 600x400, which makes it a little easier. Unfortunately, many do not understand that a lot of energy is lost if the alignment does not fit and or the optics are dirty/defective.
I open the front section and pull the timing belt by hand, from focus 0 to approx. - 150MM. I do Z (M3) adjustment in the middle of my bed and only there. The distance from M3 to the lens or the end of the nozzle does not change, therefore there is no need for the adjustment (after M3 is aligned!). If there is a difference between the 4 corners of the machine bed at the same focus height, then the other mirrors are to blame.
On my machine there is a center deviation of approx. 0.5mm at 150mm = 0.2 degree, at this distance of Z. which means an error of 0.06mm on the focus level. I consider this acceptable on an OMT machine and my bad eyes
NB. perpendicularity of the nozzle has no influence on alignment if M2 fits M3, but becomes critical when the nozzle edge hits the beam.
