This is a Print-in-place gearbox designed for a NEMA 17 stepper motor. It uses the supportless printing freedom that SLS allows to be as compact as possible. The intent is one could print the design, pull it out of the powder bed, and slap it on a nema motor as a whole unit.
This gearbox is part of a larger ongoing project which will be an SLS'ed Print-in-Place robot arm. I dont anticipate the arm being amazingly precise or inherintly useful but it would be a great "flex" print for SLS machines and would really showcase the mechanical attributes of the technology.
The model is fully parametric and was done in fusion 360. There are approximatly 16 points on the cycloid curve which define points on the mathmatically correct cycloid. These points are then connected with a spline to approximate the actual cycloid surface. Id'e be happy to do a tutorial if enough people are interested in how to model it.
There are cut outs in the side to allow the trapped powder to come out of the gear mate. In my initial testing the tolerances are acceptable but they could be tweaked if need be. I found adding a lubricant such as "white lightning" once the gear mates are cleaned out really helps get things moving. This design does have several bearing surfaces which are less than ideal but necessary for the print in place aspect of the design.