Making gears was to be a winter project for me, but not there yet, sorry, but I am sure someone will chime in soon. I just turned down a 3" dia. brass gear today. Maybe check with places like Boston gear or McMaster-Carr to see if they have them. I did work in a shop that had a automatic gear maker, just plug in the info install the right blank and let her rip, come back in a little while and it was done. The shop is no longer there and I do wonder who got that machine.
Paul