Note new version here: http://www.thingiverse.com/thing:431064 Updated adapter between a KitchenAid stand mixer attachment hub and a Milescraft 90 degree drill adapter. This version is shorter so that it will fit into the bearing housing cap (http://www.thingiverse.com/thing:39958). Note that this piece is known to fail after several months of use. A newer, hopefully more durable design is in the works. More information: http://absurdlycertain.blogspot.com/2012/07/update-2-diy-hario-conical-burr-grinder.html Available on Shapeways: http://www.shapeways.com/search?q=kitchenaidThere are two holes at tap size #29 designed for 8-32 set screws (3/16" length is good). McMaster 94355A182 is fine, for which you'll want hex key 7122A15. For most 3D print materials, you're better off driving the set screws directly into the piece rather than trying to tap the piece first. That keeps the fit tighter and allows the pieces to last on the order of months rather than on the order of weeks before failing.