# Specialty bit



## dobiepg (Mar 23, 2005)

Hiya folks,
I need to find a router bit which will cut the profile of a machine gear. I need the bit to cut a diemetral pitch of 8. That's a specific size of gear tooth.

You see, I've designed the workings for a grand-father clock (I'm an engineer by trade) and I want to make the whole thing from wood. I've looked at cutting the gear profiles with a scroll saw but that's just not precise enough to yield accurate time. I came up with a way to mass produce the gears, I think, if only I could find that router bit.

Yes, I have talked to two manufacturers about a custom profile. To date, I've had no takers...it's a complicated profile.

Thanks


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## Mike (Nov 22, 2004)

Sounds like you need a retired toolmaker with his own shop, or at least access to one. Have you tried this path? You might also try checking with industrial drive repair companies although I think they would just replace instead of repair a gear. Another place that might surprise you is a company that repairs marine propellors and drive trains. They often do custom work.


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## Neanderthal (Mar 14, 2005)

do a search for gear hobs and milling cutters. you may be able to use a shaper to router adapter to mount a small cutter in a router table, build a fixture to hold the stock. my best guess


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## reible (Sep 10, 2004)

dobiepg said:


> Hiya folks,
> I need to find a router bit which will cut the profile of a machine gear. I need the bit to cut a diemetral pitch of 8. That's a specific size of gear tooth.
> 
> You see, I've designed the workings for a grand-father clock (I'm an engineer by trade) and I want to make the whole thing from wood. I've looked at cutting the gear profiles with a scroll saw but that's just not precise enough to yield accurate time. I came up with a way to mass produce the gears, I think, if only I could find that router bit.
> ...


 Maybe if you posted a drawing or picture of what you are doing it would help. The last gear design I did was a school project 34 years ago..... I might know what your talking about but a lot of people here might have trouble knowing what a diametral pitch of 8 is much less what the bit to cut it would look like.

Having said that.... what about a small dia bit and cut the profile that way? You could do a ruff cut with a jigsaw leaving a 1/16" or so of waste to be trimmed with the small router bit. You would make a pattern to do one tooth at a time then index to the next tooth. 

The gear could be to small for this I guess, as a small router bit would be 1/8"

Just a few thoughts...

Ed


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## Dewy (Sep 15, 2004)

dobiepg
You could always do this like I would have done if still in an engineering machine shop.
I would have done it on a vertical milling machine with the piece held in a dividing head and ground your own cutter to produce the section.
Grinding your own cutter would be hit and miss unless you had access to a cutter grinding machine but with wood you would only really need one flute of the cutter ground to the profile and grind away all the others.
I've done this many times by grinding away every other tooth on a woodruff cutter then grinding the alternative teeth to the desired profile.

Oh for a Bridgeport mill in my garage


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## dobiepg (Mar 23, 2005)

Thank you for the answers folks. A couple of you pointed me toward a small machine shop. I'll give that a try and look for the retiree or hobbyist looking for a challenge.


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