Spring loaded bearing block (SC8UU replacement)

thingiverse

Update 28/9 -17: New base "v1.1 Spring loaded SC8UU - Base". Bearings was found not centered on rod, corrected in new version. Remix of pparsniak's "Smart bearing block". Great idea which works surprisingly well. The original SC8UU/LM8UU bearing lacks a good enough preload and the tolerance fit between the rods and the bearing are not as good as could be. The igus drylin bushings also have this issue, which for me actually were worse than the original LM8UU bearings. The "smart" bearing have adjustable preload, which mean that the dimension and tolerance of the rod is less of importance. I printed the original version but I wasn't happy with using rubber bands or the screws, so the main change is that this have a spring to set the preload. Along the way I also made a few other fixes/upgrades: - No need for washers. - The same base to rod center as the SC8UU. - Thicker base to fit button head hex M3 bolts for the angled bearings. - A side surface for Y-axis limit switch to hit. - Optimised for 0,4 nozzle and 0,45 extrusion width. BOM: 3x 623ZZ ball bearings 1x Spring (OD 7,5-8mm, ID 5-6 mm, ~4 mm length) 2x M3x8mm (minimum length) 2x M3x16mm (minimum length) 2x M3x25mm (minimum length) 6x M3 nut (preferably Nyloc) (4x M4 nuts for part assembly, min. M4x8mm or preferably M4x10mm bolts) The spring I used is the same as for the heat bed on the Anet printers cut down to length. Nyloc nuts are strongly recommended for the two nuts clamping the spring, washers and/or loctite thread-locker might also work. When setting the preload the general tip is that it is fine if there is some resistance when moving the bearing, it should enough so that the ball bearings are rolling and not slipping on the rod. The rods should be cleaned of any lubricant btw. I would say that this solution is best suited for the Y-axis/bed, as the centre of gravity is centered and the bed will rest down on the fixed ball bearings. For the A8 X-axis/hot end-carriage the weight of the carriage will press partly on the spring loaded bearings, which might be less rigid.