Quote Originally Posted by Mjolinor View Post
it could be that one of your motors is not as good in one direction as it is in the other, They are actually all like that but the more you pay the less the difference and generally as these motors are as cheap as they come it is a likely candidate. It may be worth just slowing everything down, printing moves and travel moves and noting the effect on the print.
I think you are probably close to correct. The belt is tight and is not slipping. I was printing on a sheet of 1/4" glass and I think it's too heavy. When it prints fill it tries to move too fast and the motor probably skips a beat at first. I'm getting a sheet of 1/8 glass and slowing the printing of fill to see if that fixes it.