[williamsmotower]

Just trying to pick a gear cutter to cut my gear. Problem I'm having is numbers don't correlate to what is available for cutters. And yes I'm a gear newbie so go easy.

I'm pretty sure it's a metric spur gear, and it's for a silent drive style chain.

I have a CAD drawing for it (Rhino CAD) if someone can look it over (send me a PM with your email address?)

Or what dimensions do you want me to list?

Here's what I have: (Yes these are in inches even though I know gear is metric)

2.4661" OD
2.3210" pitch diameter
32 teeth
20 pressure angle (guess)

I get 13.79 for diametral pitch

[HuFlungDung]

I'm a 'silent chain noobie', but is silent chain not based on a 'whole number' pitch (from tooth to tooth) or common fraction of an inch (if it were imperial chain)? This translates into what we call 'circular pitch' in gear nomenclature.

Circular pitch has a fixed proportional ratio to Diametral pitch of 1 : Pi

All this means is that standard gear cutters are not likely to be correct for the job, because most common involute cutters are based on Diametral pitch, or Module, in metric.

So by interpolating some gear charts in "Gear Design Simplified", I'd have to guess that your chain has a circular pitch of 6mm, which is about halfway between that of a 1.75 and 2 Module involute gear cutter. It may be possible to overcut/undercut the depth of tooth with the 'wrong module cutter' in order to make the tooth of correct thickness. But the allowable cumulative tooth error on a silent chain sprocket has to be very low, or the chain simply will not fit. So one really needs to get a proper cutter made, which could be very expensive to have done.

[RICHARD ZASTROW]

There are differences in dimensions between chain manufacturers of silent chain. The cutters used to manufacture silent chain are not gear cutting tools.

That said, check on the Internet for cutter manufacturers/dealers such as Ash, Barit etc. You may be able to rent the cutter needed, especially from Ash.

Dick Z

[williamsmotower]

I think what dung said about not running standard cutter all the way in. I used a gear drawing app in rhino and it turned out perfect except for root dia tweek.

That's why if someone could look at my drawing a solution may be apparent