Wood makes for some great possibilities. Our arm in 2005 (
http://www.trobotics.ca/#MAXX ) weighed only three pounds, but could support the weight of two judges bouncing on it in a three point bending test. We brought along a prototype for them to bounce on.... the rest of the robot couldn't handle the stress, but the wooden arm could... easily! I will admit to being rather surprised how strong it was, and didn't actually believe my fellow technical mentor, Gregg, that it would work until I saw him sitting on it!
The next year (
http://www.trobotics.ca/#MAXX%202 )we machined our turret on our CNC router, and pressed the bearings right into the baltic birch turret sides. Not exactly the same impact loading as on a drivetrain, but we're still shooting nerf balls from that thing. The main sprocket on the ball loader (
http://www.chiefdelphi.com/media/photos/22924 ) was mahogany, if I recall... and you'll note the Maple bearing blocks. We also machined up a Maple motor mount for the big CIM to run our intake roller mechanism.
At this point we had pretty much fallen in love with baltic birch, so we built an elevator and actuator out of it
http://www.trobotics.ca/#MAXX%202007 and last year it formed pretty much the entire superstructure of our robot
http://www.trobotics.ca/#MAXX%203
So we're big fans of wood. In fact we were seriously considering a wooden chassis for last year, untill we realized that we could build an aluminum frame using the KOP parts quicker, cheaper and lighter. But then again... we have access to a full metal shop, including a TIG welder, as well as students who know how to run the mill and TIG. If we had only handsaws and drills, this design might be an ideal solution. At the very least it is a cool design exercise to see how "minimalist" one can get.
Jason