Two different universal joint shaft couplings connect a motor to a worm gear. One the two designs works better than the other one. I designed in in OpenSCAD and put the 3D print files at https://www.youmagine.com/designs/universal-joint-with-bearings and also http://www.thingiverse.com/thing:392828 (note: these were printed in PLA on the Ultimaker 2)
