I need a small precision differential gear set about 2 inches in diameter for small loads?
I would like to mount it with trunion bearings and attach a toothed belt pulley on the outer diameter. This device will be in a product which be produced in significant numbers. Cost is an issue.
You can go for a cycloidal profiled gear - the type used in wrist watch. As you need them in large numbers, it can be made of plastic (I would prefer polycarbonate) using an injection molding die. Injection molding equipment is costly but you can always