What type of steel are gears commonly made from?

[Joe Johnson]

Unless I know otherwise, I have used 60Kpsi as my yeild for the steel teeth I buy off the shelf.

It is not perfect, but it is probably close enough for my purposes.

As to using the Lewis equation, this is WAY WAY WAY concervative. I approximate the tooth as a beam with the load a the pitch line. I use Mc/I for my max stress condition.

I know these are pretty rough approximations, but they work for me (both in my day job and in 9 years with FIRST).

As to static/dynamic loads, I pretty much just design for stall torque with a whatever safety factor I feel I can sleep with.

Weight matters in FIRST. I try to balance a robust design with one that is not so overdesign it makes me loose a match because I could not put the right enough of sheilding around some soft bit of my bot.

Everything is a balancing act in Engineering.

Joe J.