Modified from : http://www.thingiverse.com/thing:97377 M8 shaft with a higher nut trap for some adaption. Update: Added Mod_Herringbone.stl which has smaller hexagon (12.8mm approximately) instead of the original one (about 14mm). Remember : After downloaded, put mendel_misc and parametric_involute_gear_v5.1 in a new directory "inc" so that scad includes will function properly.