Compact Thomson Super 8 Ball Bushing Block (bearing block)

thingiverse

An updated design can be found at http://www.thingiverse.com/thing:534210 and http://www.thingiverse.com/thing:540629; they employ screws for precise fitment adjustments instead of cable ties. For 1/2" guide rails, bearings are held in blocks with two tie-wraps, while the blocks have #6 screw holes on the centerline, spaced 26mm apart. The flat surface is 19.05mm from the guide rail's center. To achieve fine adjustments, use small tie-wraps to secure the bearing on the rail and slide the block over it before tightening the tie-wraps while checking motion. If binding occurs, cut the tie-wrap and retry. Printed with ABS, 0.2mm layers, no raft or brim, 40% infill, and two vertical and horizontal shells; a single block takes about 90 minutes to print. Multiple blocks may experience slumping in thin curved areas due to prolonged time on the hot build platform, so consider printing two at a time or using PLA.