We have built our frame from wood for the past three years. In the past, you couldn’t really tell it was wood because of the finish we applied. This year we decided to leave it natural so that it was obviously wood. At Peachtree, most people were familiar with us and I heard no negative comments on the wood frame. At STL, I heard several people comment that our robot must not be very good because the frame was wood. Even the judges pretty much ignored us. No judge came by our pit to speak with the team until one of the kids asked them to. Then they just came by, asked a quick question or two, then left. There was a pervasive feeling that wood is an inferior material for construction, and that we must have used it because we couldn’t do any better. This is not the case. One of our sponsors is a laser cutting operation that can cut anything we want from wood or aluminum. We have built aluminum frames in the past, but we have had such good success with wood that I see no advantage to aluminum. I won’t say that wood is the best possible material for all robots or all teams. I can’t guarantee that we will build a wood robot next year. I do believe that for the last three years, wood has been the best choice for our team. I wouldn’t do it different if I had the chance. Here is a brief history of our wood chassis and how they have done.
In 2009, Sean Cantrell, one of our college mentors, suggested building our frame with wood. I was not really in favor of the idea. He made a good case about the weight, strength etc, and the kids decided to give it a try. So we used Okume marine plywood (very expensive), laser cut the parts to fit together like a jigsaw puzzle, and glued it up with marine epoxy. The frame turned out beautifully. It was light, very strong, and incredibly easy to work with. Need a fastener here? no problem, drill a hole and install a tee-nut. Need an opening there? no problem, grab a hole saw and zip, there you go. No worries about aluminum shavings shorting out electronics, no problem with the frame being a conducting path for shorts, no dents or bent parts ever. The kids decided to give the frame an automotive paint job (gloss black) and nobody knew the frame was wood. We played over 60 matches, were the # 1 pick at Peachtree, Palmetto, Curie, IRI and GRITS. We won Palmetto and GRITS, and did very well everywhere we went. If you look at that robot today, you will see that the aluminum parts are beat all to hell and back, bent, straightened, re-bent. You can now tell that the frame is wood because the paint is all beat up and worn off, but the only damage is a few wood fibers pulled up where most of the impacts occurred. Since then, we have been wood all the way. Last year we decided to go with baltic birch instead of Okume because it was much cheaper and more readily available. We used wood-woking glue and a brad nailer. Again, I was pleased with the results. We built an 8 wheel drive, 6 motor, high traction pushing monster. We won Peachtree, and played in the quarterfinals on Galileo head to head against 217 in two very aggressive matches (at one point both us and 217 were almost vertical, with no wheels in contact with the floor). We held our own, but our alliance went down in two. Several times during the event I went by 217’s pit and observed the work they were doing repairing the bent aluminum sheet metal on their frame. Our wood frame sustained no damage. It remains pristine to this day. This year, Sean decided to help out 2415, but we stayed with wood. Again, we had great success. We won Peachtree again, and were seeded #1 on Galileo. We used a Banebots 775 for our elevator drive. I don’t know if we ever had the famous case short issue (we didn’t when we installed it), but even if we did, it couldn’t cause problems with the control system because the chassis is not conductive.
If we had built our chassis out of carbon fibers laminated in a matrix, it would be considered high tech and cutting edge. Instead, we used lignin fibers laminated in a matrix. For some reason that was considered low tech. Again, I can’t say that wood is the best possible material for all robots or all teams, but for us, it has worked well. I saw that 829 built a wooden frame similar to ours this year. I didn’t see any of their matches, but they made it to the semis at Smokey Mtn and Boilermaker. If anyone wants advice or info on wood as a robot material, contact me, or I would bet that Sean would answer any questions you may have.