Engravings better on the right side of the stage (backlash?)

[typomaniac]

Hey,

i own a diy buildlog laser with lo x7 dsp control. The laser works with gt2 belts on x and y axis and v-wheels.
The laser is pretty much rectangular and the beam hits the head on (almost exactly) the same point over the whole xy stage. What i recognized yesterday is, that the engravings which are made on the far left side are not as good as the ones on the right side. You can clearly see some offset when lasering with x-swing. With the same settings on the right side everything is good. I had issues like that before but after a new set of drivers and belts everything got better. If i reduce the acceleration from now 7000 to 3000 you can see that the results improve but they are still not as good. Furthermore to me an acceleration value of 3000 sounds pretty slow (maybe i am wrong so please correct me?). Do you have any explanation why the left side is worse? The belt is not sloppy. Maybe i can improve some other settings?

thanks a lot,
tm

[Techgraphix]

Have you checked the head's carriage for freeplay all over the gantry? As you use V-bearings and probably the aluminum profile as known from this buildlog laser (2.x ?) there can be spots where there is a slight difference in friction. When you pull the carriage somewhere at the top it can tilt a bit when there is more freeplay at that point. Even the smallest angle will be visible in the result.
Best way to guide the head is using liniar guideways with blocks, but you have to modify the design drastically..

Kees