Gear Pressure Angle and Pitch.

[Patrick Wang]

In the continuing quest to build a gearbox, yet another question has popped up. (perhaps these threads will turn into a gear FAQ?)

I've been looking around for people who sells gears. Mainly McMaster and BERG. What I've seen in the Mcmaster catalog however, is that their selection of gears of 20 degree pressure angle seem somewhat limited. Now their website states that the 20 degree pressure angle is a new AGMA standard for higher torque carrying capabilities, but they don't seem to offer any plain steel 20 degree spur gears under 24 pitch.

BERG on the other hand, has a much greater selection of gears.

My Question, mostly out of curiousity and to see other people experiences, is

-How significant is the difference between the older 14.5 degree pressure angle gears and the 20 degree gears.

-What pitch gears have you used, and how were the results?

The original plan was to use 20 pitch gears at 20 degree pressure angle, but I am having problems finding one with a finished keyed bore. (our machining resources are limited)

I have however seen that Mcmaster sells 14.5 degree pressure angle gears with finished bores, and am looking for a viability in them.

Thanks again all!