I found that if your motors run hot, and your gear is printed using PLA, the set screw can loosen because the gear warps a little. This is a Bad Thing(tm). To address this, for people with the right tooling (e.g an M3 tap, a 2.5mm drill bit and a hand-drill), I added a slot for a nut into which you pre-drill a hole and tap a thread for the setscrew. I also made a depression for the setscrew head so that it does not protrude from the hub of the gear. This allows it to be installed inside the mounting hole of the wades carriage if this is necessary to mesh properly with the large gear on the hobbed bold.