[Sean Schuff]

Our team (93) has gone through many of the design iterations that other teams have gone through. Wood and PVC tubing to aluminum angle to aluminum tube to unistrut (extruded profile).

We've chosen to stay with the unistrut for our base/drive frame because it really can take a hit and maintain it's shape. And judging from the evolution of the FIRST game, high-impact is going to be here to stay!

This past year we experimented with fiberglass reinforced plastic or FRP. One of our structural engineers clued us in to it's incredible strength to weight ratio and we used it on many of the upper structural components on our 2004 robot. The light weight kept our CG much lower than if we had used unitrut or even aluminum tubing up that high.

For connections we machined unistrut down to a size that allowed us to slip it in the end of the FRP with just a snug interference fit and used unistrut fasteners to tie it all together. On a side note we also made extensive use of nylon bolts and nuts and, much to my surprise, they held up quite well. I can't recall a single one failing in competition. You'd be surprised how much weight you can put into fasteners on a FIRST robot and switchig to nylon really helped us out.

One benefit to the FRP (and this carries over to aluminum tube as well) is the ability to route electrical and pneumatics through the frame members to keep them out of harms way and give your robot a neat, clean appearance. Make sure your design is sound, if you have to replace a structural component that has elec/pneu running through it, you want to be able to do it quick!

Another benefit of the FRP is that when it takes a hit it flexes and returns to it's original shape. Aluminum, on the other hand, won't return if bent too far.

The FRP held up VERY well for us and we only had one frame member (not critical) crack on us. It didn't break completely but it must have taken a good hit from the corner of another robot. And if you remember our robot from 2004 (the big green and blue laundry basket) we took a lot of hits from teams trying to move us out from under the ball drop.

If you're looking for a different material to use on your robot, consider FRP. It's pretty sweet stuff!

Sean