This is a replacement / upgrade to the Robo3D R1 and the LM8UU linear bearings used to guide the Y Axis of the moveable bed. This model uses self-aligning self-lubricating sintered bronze bushings instead of ball bearings. Advantages are operation with less mess and little or no lubrication is needed along the rails. Quieter operation from the solid bronze bearings. No possibility of gouging the rails in the event of a bad or dry ball bearing. This pillow block uses 7Z41MPSB08M bearings available in the US from Ultibots.com Designed to be printed laying flat. When doing so support will assist the center hole stay round but is not absolutely necessary. Can also be printed from either end with no support. Please print this with ABS or other filament with a higher Tg (Glass Transition Temperature) because of the close proximity of the top of the pillow block to the bottom of the bed heater. Alternatively, insulating the bottom of the heater pad may also provide satisfactory results. There are a few significant differences between these blocks and the OEM Robo3D blocks. They are one single piece. Instead of using two pieces like the Robo, it is designed to hold the bearing without artificially compressing them while fastening the block to the printer. The holes for the bolts are recessed. To allow for more room under the bed, the screws are recessed and can use readily available socket head cap screws which allow for easier installation over phillips head screws. Uses self-aligning/lubricating bearings over LM8UU. Bronze bushings provide longer life, less maintenance and quieter operation over ball-bearings. As a result of bearing design and placement, the effective support length is actually increased without increasing the size of the block itself. The model as well as 3D solid source files, in a variety of formats, can be found on Thingiverse. Autodesk Fusion 360 was used to create this model. X Axis bearing replacement thread located here.