I'm a Solidworks novice, and I'm stuck trying to model a Hirth joint:

http://en.wikipedia.org/wiki/Hirth_joint

I'm thinking it would be really simple to model if I could sketch directly onto a cylinder. The best strategy seems to be lofted cuts, but I'm not successful so far.

This version doesn't seem to have any interferences in the assembly, so unless someone corrects me i'm going to assume this model is correct. If anyone is interested in using it, the radii, number of teeth, and profile angle can be changed independently in the equations manager.