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- Jan 21, 2015

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No problem. I wrote a Java program in about 20 minutes that allowed me to search through various tooth counts to get what I was looking for. I had the program try lots of values that were still reasonable. So here's one possibility:

Hour wheel: 84 teeth. Mates with 8 leaved pinion on 2nd wheel. Ratio: 10.5.

2nd wheel: 64 teeth. Mates with 7 leaved pinion on 3rd wheel. Ratio: 9.143.

3rd wheel: 45 teeth. Mates with 6 leaved pinion on escapement. Ratio: 7.5.

But that's 3 different pinon cutters to make. So I thought maybe this one is easier:

98:7 , 60:7 , 42:7. This has the advantage that all the pinions are identical, but does introduce an integer ratio there at the end (42:7 = 6:1).

I'm considering buying a cutter set (probably 0.5 or 0.4 modulus). Then I thought if I constrained the pinions to at least 10 leaves, I wouldn't have to make any pinion cutters at all. Usually a cutter set of a particular modulus includes cutters down to 10 teeth. So I thought maybe:

120:13, 104:10, 75:10.

Now we're getting up there with 120 teeth on the hour wheel (only 1.5 degrees per tooth)!

What's the thinking here? What should I be looking for in my huge table of possible gear ratios? Any help would be greatly appreciated.