I just realized that I've never mentioned what material we work with..
We use 6061 aluminum for everything. The only steel on our robot is the
gears and shafts. So the only real machining of steel we'll do is
keyways.
Does that change any of your advice? (esp concerning accuracy.. im
guessing alu is easier to machine..)

Tatsunori Hashimoto. Harker Robotics