I have a Shenhui 350 Laser. I use it mostly as a hobby machine, so even though it's three years old it has not got that many hours on it.
Today I cut some 3mm (1/8inch) birch plywood but that did not go well at all: the line did not end where it began. (See attached picture, the little bump on the recess top right is intentional)).
laserskips.jpg
It looks like it is skipping steps, but the rest of the shape appears to be smooth. I would expect some small bumps on the curves where the skips happen, but the whole shape is smooth. Except of course where the cut begins and ends, here is a difference of 0.1 to a whole millimeter. It is not consistent, sometimes it cuts a shape just fine, the next try on the same shape it's off. And this happens in both X and Y, which is another reason why I doubt it is simply skipping steps...
I checked the tension on the belts, seems to be ok. When I slowly move the carriages by hand I cannot feel any obstruction whatsoever. I also tried cutting at different speeds, no difference.
Also this appears to have started overnight. I cut a lot of cardboard last week without this problem.
Maybe related is that as long as I have this machine, the x-axis is almost silent, whereas the y-axis motor always makes some noise. Now when I cut a straight horizontal line I hear the sound that is related to a slow y-axis movement. Moving the head with the controls on the machine itself still sounds as it always has.
Does anybody have any tips how to determine where this fault is coming from? Can it be a software fault?