3D printed elastic couplings for Z axis of 3D printers.

thingiverse

This is elastic coupling to connect NEMA 17 stepper motor to Z-axis threaded rod of Prusa i3 and other styles of 3D printers. To the best of my knowledge these are very good if not the best you can find presently for free on the Internet. The coupling comprises of 2 parts, assembled after printing and then the holes for the M4 set screws are tapped to ensure alignment. Print orientation is important, since the spherical surfaces of both parts must be on top in order to ensure they are smooth enough. Print with 0.15mm layer height, PETG filament. Put a rice bean sized drop of bearing grease or vaseline on the spherical tip of the insert before assembly to provide some lubrication. I tested these on my CTC Prusa i3 Pro B printer and they improved print quality dramatically, no more Z banding despite the M8x1.25mm threaded rods of this machine are not perfectly straight and alignment is poor. These 3D printed couplings do better job than the classic spiral cut aluminum ones, and they cost next to nothing. Here I include .STL files for attachment of M6x1mm, M8x1.25, TR8 1 start and 4 start threaded rods to the motors. Also, there are 3 versions of the insert, which differ only in diameter to allow good fit depending on how precise your particular 3D printer is, so one of them would fit best. These are so small that just print them for testing. The inserts can be printed in PLA if you prefer, but the main body must be PETG, since PLA is too rigid and will not work well for this. Also because the grease may degrade it. Please leave a comment with any questions and suggestions.