Simple coupling to upgrade original rubber tubing on z-axis for CTC Prusa i3 Pro B. Where the original motors meet the threaded rods, the rubber tubing is a bit lame. This is a simple upgrade which clamps the threaded rod to the motor shaft.
It's easier to fit and much easier to remove or adjust if necessary. You'll need to print 4 of these (2 for each motor) and will also need 8 M3 bolts and 8 M3 nuts to hold the clamps together
Note: It's probably best to print this with the flat face of the long axis facing the print bed. As the central bore is thin, supports are quite hard to remove. Without supports there is some minor sagging, but this doesn't seem to affect the operation of the clamps. If anything it helps, providing a rough surface for the threaded rods to knit to. Some filing might be necessary in the central bore, but perhaps not, depending on print quality and any sagging.