Well, I switched around the stepper boards, and found no changes whatsoever. So either all boards are faulty, or none are.
At the moment I have doubts that the boards are the problem. Would in that case not a large object have a larger error? If the size difference is 1%, it is one mm on 100 mm, and one hundredth of a mm on 1 mm. But the error is always about 0.25 mm. So my 100 mm is 99.5 mm, and my 5 mm is 4.5 mm.
Oh, and both in X and Y. no idea about Z.
I have experimented a lot with Cura settings horizontal expansion and horizontal hole expansion, but found no solution with it. Horizontal expansion also closes the holes further, and countering this with horizontal hole expansion disforms the whole thing.
I tried connecting directly to Cura and repetier host, latest versions on OSX Big Sur. Cura can control, but doesn’t show respons on the screen, and repetier says it’s connected, but doesn’t understand the printer. So no results with gcode commands yet. Should I try a windows machine for that?
Again thank you for all advices and support.
All best, Wilco