I never had any luck hobbing a bolt using the tap method. When I used my rotary tool by hand, the teeth came out uneven.This work in progress jig should allow for either a 8mm, or 5/16" bolt (or rod with nut) to be indexed to 19 positions. The ratchet head was edited from this excellent thing: http://www.thingiverse.com/thing:8752I put up a short 30 second video of this jig being used. I was holding the camera, and using the rotary tool and making sparks fly all at the same time. With some practice, I feel I will be able to make many bolts for my army of 3D printers. http://youtu.be/KpnZK_AJLgMThe idea for this thing came to me after seeing many great ways/things to hob bolts. (That and after the snow I didn't want to go out to the cold work shed) My thing is an amalgamation of many of the ideas found here on Thingiverse:http://www.thingiverse.com/thing:9291 http://www.thingiverse.com/thing:10360 http://www.thingiverse.com/thing:10110 http://www.thingiverse.com/thing:11275Print one Ratchet gear Print one Block-Place a bolt into the ratchet gear so that the bolt head sits flush with the gear. -Insert the bolt into the jig block. -if you have one, insert a 608 bearing into the jig, and snug it in with a nut and washer -secure the jig in a vice, or clamp. (or hold it if you feel brave) -use a rotary tool to grind your first tooth into the bolt -rotate the bolt clockwise one notch -use a rotary tool to grind tooth into the bolt -rotate and repeatThis was designed with Sketchup. The skp file has been added for others to work with.