Question, antique gear cutters

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Question, antique gear cutters

New postby mars-red » Fri Aug 24, 2018 1:51 pm

I know this is probably a long shot but I know Reid gets his hands on some wild stuff from time to time, and maybe some other members might have come across a similar situation before...

I have some (I'm not going to call them a set) old watch gear cutters that are very very nicely made (incredibly high tooth count), manufactured by Rivett. Each cutter has a number on it, and the range of numbers indicated to me that they were likely to be Carpano numbers (especially given the likely age of the cutters). Malcolm Wild's book on wheel and pinion cutting has a handy reference table showing conversion of Carpano numbers to module. I've had the cutters for a few years now and finally got around to trying one of them out recently. The first attempt was a failure because the calculated diameter of the blanks for the tooth count I was wanting ended up being wrong. In fact it was off by roughly a factor of two... I cut my tooth count in half and for that same blank diameter, while they didn't come out perfect, were very very close. Diameter for the tooth count of a given DP was determined using several online gear calculators, so I'm confident that's all fine. I either made some mistake converting the module from Wild's table to DP, or I am misunderstanding something about his table, or the numbers on these cutters are not Carpano numbers at all.

I think this boils down to 2 questions:
1. Pretty unlikely, but has anyone here had experience with Rivett watch gear cutters before?
2. Has anyone here used Wild's Carpano conversion table before, and if so is there something non-obvious about it's use?

Crossing my fingers now, haha.
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