Prusa MK4 / MK4S modified y motor holder

During assembling my MK4 I realized that I was not able to perfectly align the y belt and after closer inspection, I saw that the motor is slightly canted when tightening down the screws, since the thermal pad is slightly thicker and not planar to the mounting surface of the motor mount.

I checked with a feeler gauge and in my case there was 0,2mm missing.

Didn't think too much about it first, but after having massive VFA problems on the y-axis, I started investigating and one of the solutions to make it better was to make sure the y belt is properly aligned.

Luckily Prusa provides us the step files for the MK4 parts so I could modify the current R3 y motor holder and make two new versions, one with +0,2mm added and one with +0,3mm added.

I printed both versions and both helped me to keep the y belt aligned as intended, ended up using the 0,2mm version as it gave a better contact for the thermal pad to the frame.

Both models have additional markings along with the R3 to indicate the additional +0,2 / +0,3mm.

The y motor holder is easily accessible and can be swaped out after you built your printer, just don't forget to check your belt tension, once everything is adjusted.

The VFA's on the y axis are not 100% gone, but they are a lot better now.

All printed in PETG with Prusa defaults

0,2mm detail

15% grid infill

It's the current R3 version of the y motor holder but I added +0,2 / +0,3mm to the contact surface to the frame to compensate the thickness of the thermal pad.