Here is our transmission this year
http://www.chiefdelphi.com/forums/sh...ad.php?t=44659
9 lbs with 2 CIMs and pneumatic cylinder and wheel.
Here is our transmission from last year
http://www.chiefdelphi.com/forums/sh...ad.php?t=35272
13.5 lbs with pneumatic clyinder, 2 CIMs, Fisher Price, and AM Planetary (way too big and way too heavy)
We use steel 20 pitch gears (3/8" face width, 14.5 degree pressure angle this year) Martin gears purchased through Motion Industries. We buy bearings from McMaster Carr and Small Parts (p/n brf-06 and brf/08). If you are looking for a standard R8 bearing (1/2" ID, 1.125" OD, 5/16" wide, non flanged), eBay is a great source. They are dirt cheap and appear to be good quality.
You can also get gears from McMaster Carr (smaller selection), Boston Gear, Berg (expensive), SDP-SI, and Small Parts (expensive).
We use Autodesk Inventor for design and manually calculate ratios, speed, torque, and pitch diameters and whatnot.
I'm not sure what you mean by testing tolerance. We put our gears at nominal center to center distance plus .0005 (half a thousandth) and they run very smoothly with no breakin required. But, the .0005 is only applicable if you have a good CNC machine. Otherwise, just put them at nominal C-C and run them in a bit.
For a good design in a shifting transmission, I have spent countless hours trying to come up with something really new and better than what I've seen before, and I couldn't. The AndyMark type layout really can't be beat for weight, compactness, and simplicity. You can vary the ratios and sizes of the gears and shapes of the plates, but it is hard to beat that layout.
Let me know if you need any help, as I mugh enjoy designing FRC gearboxes.