profiles of commercial clock cutters

[oldetymes]

I am seeking to understand what the profile change is for a given set of 8 commercial clock wheel cutters i.e. trying to understand why one cutter with the same module or pitch doesn't work and instead one needs the range of 8 cutters for the different number of teeth. Would someone have pictures of the first and last cutter they would be kind enough to send me. Pictures that would provide a comparison to discern the profile difference. Or if someone can put that into words - much appreciated.

thx. Dave @ Olde Tymes Clock epair

 

[LaBounty]

Hey Dave-

Thornton's order form shows 6 different cutters for a single module...

1. Pinion of 6 leaves
2. Pinion of 7 leaves
3. Pinion of 8 -9 leaves
4. Pinion of 10 - 11 leaves
5. Pinion of 12 - 14 leaves
6. Wheel of 35 - 140 teeth

Here's a photo of two Thornton cutters which are both 0.3 Mod...



Here's what the profile of the cutters look like...



The cutter on the left is for an 6 leaf pinion and the one on the right for a 8 leaf. The cutter for the 6 leaf pinion will cut a slightly shorter leaf than the cutter for the 8 leaf pinion. The 8 leaf pinion will also have flanks which are slightly more vertical. The space between leaves will be slighter greater on the 8 leaf pinion than the 6 leaf.

Bergeon has a set of 26 cutters, each of which covers 3 - 4 different modules. For example, cutter no. 3 is for mod 0.24, 0.25, 0.26, and 0.27. There is enough overlap that a 0.25 module cutter could be used to cut a calculated module of 0.27.

I don't know which set of 8 commercial cutters you are looking at but I don't feel it would be necessary to purchase every single cutter for every single module. A starter set of a few of the more common ones would be worthwhile. Then you could purchase specific cutters as the need arose.

Hope that helps!

 

[itspcb]

David beat me to it while I got my camera out!
Heres a no 1 and no 8 side by side,
Note the cutter for the largest number of teeth has straight sides, not applicable in much clock work but relevant when making racks for machinery.
There's no quick way to learn about gears, it's complex if you yearn for understanding!
Peter

 

[oldetymes]

Thx much Dave & Peter. the pics are great. I can see how the tooth curve (addendum) is changing as the wheel diameter gets
larger. That's what I was hoping for.


Dave - I can see a couple of clockclass topics being born here.

thx much.
dave M