I have sort of a rough and tumble #6 that I made up of 2 partial outfits. It's a Century RB Cycle Graphic 5X7. All the pieces have been languishing in my upstairs studio until the other day I decided it's rotation on the project list has come. This one is governor, not fan. Motor runs fine. The original lens is long gone. Bummer. That means I need to do calcs to figure out gears etc. The lens I think I'd like to begin with is a Wollensak Tasope 10 1/2". Who can help me with the formula to calculate the gear? The big sun gear has 290 teeth. But I'm not at home and don't have the radius of the big gear. Gears I have available for it are 33, 35, 43, 51, 99. I've got a ton of 5" Aerial Recon film to use up. Easily accomodated to the 6 outfit. I did measure the circumference of the drum. It is 9 9/16ths inch with 3 wraps of film on it. She won't be pretty, but she'll run! I would love to have the complete mathematical formula that arrives at the number of teeth gear to use. Len Robertson, are you still out there??