Mm, I thought the fact that being a prime number would be the stopper. I don't have CNC, yes, I have the RV6. I am looking to follow "Chris of Clickspring" and build the Antikythera mechanism. There are actually 3 high tooth count gears and he does them by file. I haven't downloaded the files yet, but a look at his videos put the diameter around 5 inches. This project appeals to me as an astronomer and I can sit down in the workshop to machine it. (Arthritis)
Tornitore45 your suggestion has given me thought.
Thanks to all. I'll think some more and brb.