gregs geared extruder with smooth outer for glued GT2 Belt

thingiverse

The small herringbone gear my bowden extruder kept slipping so I thought as I had spare aluminum belt drives, I would try to belt drive my extruder. Unfortunately, I ran into two problems with this: (1) I couldn't get a print replacement large gear with a positive enough location on the belt; (2) I would have to order a belt since splicing GT2 belt is not very reliable. Then I thought maybe if I glued GT2 belt to the outside of the larger gear it would mesh nicely with the aluminum gear, and it did. In fact, its way better than the herringbone gears have ever been: almost no backlash and very quiet. Print out and prime the edge with cyanoacrylate; once dry, wrap your GT2 belt around and cut to length with a 5-tooth overlap. The teeth probably won't perfectly line up at first, so scrape the cyano'd surface all the way round with a Stanley knife blade, checking regularly until the match is perfect. Then cut the belt at a 45-degree angle on both ends and use a rubber contact adhesive to glue it on. You'll have to re-calibrate your firmware for extruded steps per mm, and you're good to go!