Quote Originally Posted by GND View Post
Also worth checking the squareness of your X & Y axes to one another. I had similar problems with my home built machine, and after much checking and testing, it turned out to be down to a v small error in the angle between the axes. Quite tricky to measure, and even harder to fix!
One of the advantages of a twin-motor long axis is the ability to square up the gantry during homing.