Customizable Prusa MK3 Y-axis Bearing Holder

thingiverse

This item will allow you to press-fit sleeve/slide bearings for use with the Prusa MK3 y-carriage. The largest bearing it can support is 15 mm x 25.7 mm (OD x length). It should only be used for sleeve/slide bearings that are not encased (these are weaker, and generally designed to be press fit into a housing/block). By avoiding the use of U-bolt mounts, you avoid deformation of the bearing. It will also compress down on some bearings which are required to achieve the specified fit and to minimise play (see quote below). <blockquote><i> iglidur® bearings are press-fit bearings. The inner diameter adjusts only after press-fit in the proper housing bore with a recommended (H7) tolerance. The before press-fit oversized dimension can be up to 2 % of the inner diameter. In this manner, the secure press-fitting of the bearing is achieved. Axial or radial shifts in the housing are also prevented. </i></blockquote> Note that the lack of axial shifts also mean that if your smooth rods are not parallel, they are more likely to bind. This is the reason why prusa sticks with U-bolts. I designed these with the drylin RJ4JP-01-08 bearings in mind. The RJ4JP bearings do not officially need a press-fit, but they can be compressed to fit smooth rods of different tolerance specifications, reducing play. Customiser settings: 1. bearing_od - set this to the specified bearing OD 2. bearing_od_loosen - how much to loosen (or tighten) the bearing press-fit 3. bearing_lip - whether to print a lip or not - a lip stops the bearing from being pushed out of one end 4. bearing_ln - set this to the specified bearing length - this is only applicable if you set bearing_lip to true I have attached a few STLs for RJ4JPs (and different compression amounts). Addit (25/9/18): - I initially had RJ4JPs on a 4-bearing y-carriage MK2S replacement frame (P3Steel). This worked well for many months - I noticed excess wear and increasing play from my RJ4JPs (~ 4months), and switched back to the original LM8UUs - Your mileage may vary