Self Aligning Bushing Block

thingiverse

If you are having trouble with the Z axis on your Thing-O-Matic, losing steps, binding, non repeatable Z, etc, these may help. Plot these blocks, install an o-ring and bearing to improve Z axis stepping Instructions How it works: 4 rubber o-rings installed in the bearing blocks with the bushings pressed in allows each bushing to rotate slightly with little force to compensate for the shaft axis not running parallel with the bushing. Additionally, the o-rings provide sufficient radial stiffness for plotting, yet provdide a little give for slight radial misalignment (tolerances). The additional bearing spacing adds stability, and the o-rings damp vibraiton (noise). Parts: 4 bearing blocks (plotted), 4 bronze bushings (from the Makerbot Z axis), 4 #12 Faucet repair O-rings (from the hardware store), 8 #2 x 1/2" wood screws (from the hardware store). This is a $5 upgrade to the Z axis that makes the bushings self-aligning with much less binding, and quiets the Z axis down significantly on a Thing-O-Matic. Assembly: 1) Plot 4 copies of these bearing blocks. 2) Install a 5/8" ID x 13/16" OD O-Ring (#12 Faucet repair O-Ring) in the groove in the top of each block. 3) Remove one bronze bushing from the Makerbot Z axis plywood (one at a time seems to work best to allow the remaining 3 to allow the new block to be aligned) and press into the o-ring on one of the blocks (from the top). 4) Mount the block on the Z axis: The blocks fit on the "outside" of the Z axis such that the bearing span gets larger than the original configuration. Place a block with bushing installed on a shaft and resting on the plywood. Mark the 2 mounting holes and pilot drill them with a 1/6" drill (or smaller). Fasten the block with 2 #2 wood screws. Wiggle the block before fully tightening the screws to ensure there is play for alignment. If the block does no wiggle, drill the mounting holes out to generate sufficient clearance. You can also drill everything out and use M3 nuts & bolts if that is easier. 5) Repeat steps 3 & 4 for the remaining 3 blocks. Note: Clearance is tight to the shaft retaining bolts at the top of the Z axis. Putting the bolt heads on the inside (nuts on the outside) worked on my Thing-O-Matic, a button head or flat head screw will also improve clearance if it is an issue. Lowering the Z axis home switch also could help.