[Jim Zondag]

Deepwater, Thanks for the compliments: to answer your questions:
1. The wave washers are used as needed to take up lateral slop in the assembly. If you make everything perfectly, you don't need them. If you have student welders and lathe operators like I do, you may find you need some.
2. You can use steel washers if you like. We typically use aluminum washers for everything on FIRST robots. It is amazing how much easy weight you can save if you have hundreds of washers on you machine.
3. The Grayhill sensor is just a suggestion...you can use any similar device here. The number of counts per revolution you choose will depend on much resolution you need/want. I like this one and we made a interconnect so that we can disconnect it right at the transmission.
4. Hardening, I had our heat-treat lab do this for us....I told them to make them hard and they did. Being a programmer I am somewhat ignorant on the details of metallurgy...another great opportunity to learn through FIRST! I will get details and reply later.