[s_forbes]

2 points of input:

• Gear clearance - You have the spacing between adjacent shafts set to the exact pitch diameter of the gears, which in a perfect world would work. If you add up tolerance issues with the gears, shafts, and machining precision of the plates, you could end up with gears that are "too close" and bind. Its suggested to add a little bit of extra space between shafts to compensate for that and get a smoother running gearbox. We add 0.003" between meshing gears in our transmissions.
• Retaining ring on the output shaft - Retaining ring grooves are stress concentrators and reduce how much torque you can put through the shaft. You should try to avoid putting them in a section of the shaft that transmits power. I'd suggest looking for a different way to retain the shaft, or perhaps just move the clip all the way to the end of the shaft, past the wheel. (I'm not sure that you'd even be able to install it as pictured, since the rings don't open far enough to go over a hex shaft. An E-style clip could be installed though.)

Structurally it looks like it is strong enough for FRC applications, though I'd prefer to use larger diameter standoffs.