[sanddrag]

Certain geometry can be difficult to model with equations, and to be honest I've been out of it too long and my skills are rusty there. For this short-life less-than-critical application, you may design just based on others' experiences and trial and error. You could plop it into some FEA package but any professor skilled in such things will tell you the results are garbage unless you really know what you're doing, and even then it's only an estimate.

Depending on the application, based on my first-hand knowledge of 968's 2007 transmission analysis, I'd say with steel gears you're good to take them all the way down to 1/16" web thickness with holes even, and you can probably take them to 1/16" remaining beneath the dedendum circle, and maybe 3/32 around the hub bore/keyway. And it's nice to do the pocketing with a ball endmill to leave a radius where he pocket meets the tooth area or hub.