Prusa MK3/MK3S Y bearing housing

Prusa MK3 Y Carriage bearing holder

A LM8 bearing holder which replaces the original U bolts under the Y carriage.

A refined version based on LM8 Bearing holder MK3 (which is turn based on the Prusa i3 Bear Bearing Holders) which has been optimized for slicing with PrusaSlicer and only for 2xM3x20 button-head or flat-head screws, placing the screw head as close as possible to the bearing.

Slice with 0.15mm layer height, 3 perimeters, 15% infill using a 0.4 nozzle.

These fit the Original MK3 but, as mentioned on similar designs, with very tight tolerances (picture should give you an idea!) due to the geometry of the screw and carriage. The Y carriage needs to be pretty-much-perfectly aligned.

After assembly, press on the bed to ensure that heavy prints can still clear past the X frame! Ignore this design if unexperienced or when in doubt! There are other designs which flip the head of the screw to be on top of the carriage, and thus thread directly on the holder's plastic, greatly increasing the clearance.

That being said, this design avoids uneven over-tightening of the bearings, while also holding the bearing itself along it's length, improving Y axis homing accuracy. I've been using these on several MK3 printers with careful adjustment without issues.