China Laser Mirror Alignment Problem

Good morning from Germany,

we have an unknown problem with the alignment of the mirrors of one of our China Lasers. In the picture you can see laser focal points from all 4 corners. Three of them are almost on top of each other, but one is far away. Looking at the laser from the front, it is the upper right corner. We have aligned the axes and they fit, but we just can’t solve this problem. If we want to bring the upper right corner closer to the point of the lower right corner using mirror 1, the point from the lower right corner moves parallel. Due to this extreme shift, the laser power towards the upper right corner decreases vehemently.

Do you have an idea what could be the reason for this? With our other lasers we never had this problem. We have already tried for 2.5 hours today, unfortunately without success.


Is your Y driven by one or two steppers? I’d start to look at the belt, pulley, mechanical parts. I have a feeling the left side is being pulled tighter than the right side at the upper limit.

This is a very good how to video on the subject. It’s a little slow to start with the YouTuber tooting his own horn with the intro and how amazing his machine is but once he gets to the point the video is very useful

Good luck


That video is :sob:.


Almost inspires me to make a good video on alignment.

I warned you… :rofl:

Nevertheless it does have some useful info once you get past the BS

I think you should do a video @Stroonzo



Sorry for this very late response! We were pretty busy for the last weeks…
Yesterday we found the solution for the problem. The left sided belt slipped through at some time, in follow the belt had different tensions upside and downside and it follow of this the y-axis moved slightly diagonally. We moved the left side mirror first by hand a bit and saw that this improve the result. At last we slightly loosen the gear of the backside step motor and with this we distribute the tension even. After this the problem was solved. :slight_smile:

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