I have a problem with mine 30*40 cm 2500mW laser from Banggood. I assembled it according to instructions - frame is sturdy and square. No problems with software/drivers.
But, when I try to burn something, I cannot get straight lines on X-axis.
Originally I thought that wires were too short and strain from them pulled laser cartridge, causing this "wiggle". So, I extended both wires (motor and laser) by soldering (no connectors were added).
To eliminate any pull-force I installed "wire support" to run wires up from control board and down to cartridge. This did not help.
Then I though that cartridge is unbalanced (I can quite easily wiggle it on rail), so I put some weight on one side thinking that this force will put it to same angle all the time and I will have straight lines. This did not help either..
Lines are wiggle, but parallel to each other, so it's something mechanical. I thought that it could be warped rollers, rotated them separately, but this did not help either.
My last resort will be reassembling laser cartridge and rotating it's rail upside down.
Any other suggestions?