I print oversize

electroman

I made my DIY printer based on Prusa.

My probleme are that the z work fine with the right scale of print but on x and y, the printer print biger than it must about 25 percent. I use 200 step nema 17 (1.8 degree) with a pulley of 20 teeth with MT2 strap so each turn generate 40 mm of displacement

with 1/16 microstepping, I have 3200 pulse per turn divided by 40 egal 80 step per mm.

But I have more than 20 percent more. Just a way to search because I lost ma latin on this trouble.A hint to know the direction to search.

Thank a lot.