I recently sponsored a Kickstarter project for a Makesmith CNC router. It has some plastic gears that are easily misassembled, so I created some parts to make the gears be easily attached without needing to align them. (they attach to a FS90R servo and a ¼ / 20 threaded rod 7/16" nut). It should be able to adapt easily for other projects as well.Super glue a nut in the nut gear, and a screw into the servo side. align the rod with the servo and it should couple easily.