Two of my coworkers and I decided it would be fun to have a little competition of who could build a machine to throw a 3-5 pound pumpkin the farthest. The rules were simply that it had to be mechanical where it could release stored energy into hurling the pumpkin.

I went to Home Depot one Saturday with a drawing of my design with measurements. It was just like the commercial, a guy confronted me right away and then became very interested in helping me. I guess they don't get to build siege machines very often. I got back home with a bunch of two by fours of various lengths. I had originally planned an axle height of five feet, but with the few extra two by fours, I figured out a way to optimize what I had so that I could make the axle height be six feet. That way I could have a ten or twelve foot throwing arm instead of a eight foot arm.

My axle consisted of a three foot steel bar that fit very nicely inside of a copper fitting which I wedged into the throwing arm. The steel bar had fitting groves on each end so I figured I'd cap them and screw the cap into both support arms. This looked great and even though it was difficult, allowed me to unscrew the axle for transport. The groves were unfortunately too weak for the pressure and snapped when I was turning the whole trebuchet on its side.

I instead had to secure the axle to the arm supports by drilling a hole in each support and tying the axle to each with rope. This was not as secure as I had hoped but proved to be no problem when throwing.

My release trigger was an "L" shaped hook that slipped inside of a loop on the throwing arm and hooked to the base of the trebuchet. It didn't take much to pull this hook out and to trigger the throw and worked very nicely. To be safe I always attached a thick chain to the arm until I was ready to launch.

My counterweight consisted of two huge painters buckets filled with concrete, sand, rock salt, and bricks. They totaled about 130 pounds together. The first time I tried a dry throw (no projectile) with both buckets attached, the S hook bent open and both buckets fell to the ground with the arm swinging wildly. So I got much thicker S hooks and chain links. I would have gone bigger in the weight but I would have needed to turn to slabs of metal to keep the overall dimensions of the counter weight from getting too big.

Luckily I was able to borrow my friend Ashleigh's pickup truck, otherwise I never would have been able to transport my trebuchet to work for the competition. When I build 'em, I build 'em big :)

I had tested numerous times with tennis balls, but my first real throw occurred in my work parking lot. We threw towards the Hudson River one at a time. It was more for fun then it was for a competition. A bunch of people had come from the office to watch and cheer.

Kevin also built a trebuchet. It was smaller yet had more efficiency than mine. He had a much lower angle throw, whereas mine would be extremely high. My throws had a considerable hang time. He built the support arms using hinges so that he could easily transport the machine in the trunk of his car. I barely threw farther than his, and his fit in a trunk, heh.

Ameet built a type of Mangonel out of PVC piping. Using a little pulley system for mechanical advantage, he was able to get a great snap out of those pipes. The problem was that he needed to secure the machine to the ground and it was very light. So he used one of our bosses as a weight to hold down the machine.

I'm now looking for a convenient way of transporting my trebuchet so that when the weather gets a little nicer I can test it on weekends. I imagine a small two wheeled boat trailer would do the trick. I would securely attach the trebuchet to the trailer to give it more support as well. It's currently outside gathering snow and taking up space.

This is my favorite picture. You can see the pumpkin coming back down from its high trajectory.

Stats:

• 10 foot arm with 2 feet for the short side and 8 for the long
• 12 x 3 foot long base
• 6 foot high axle
• 130 pound counterweight
• 6 foot sling

Well we never had to raise the height because no one besides for me could get over. We had developed the rules so that anyone could enter and not have to spend too much on parts. Unfortunately there were only two others who had machines.

My machine used rubber bands in between the hinges to pull itself together and launch itself into the air. I had drilled holes in the feet to allow for a wire hanger to rest in front of the machine. That way I could angle it towards the wall and not jump straight up. Also, by counting the number of rubber bands, I was able to consistently jump the same height.

Stats:

• $5.84 on supplies
• 15" wide, 12" long, and 5" tall (compressed)

My robot's name was BottomDweller and did exactly that. It would travel to the bottom of the screen and then continue to go left and right along the bottom aiming upwards. I had written a targeting mode (used mostly for one on one) which kept track of where my enemy was last and guessed where he was going to be next. Using this predictive target sweeping, I was able to keep my gun facing my target a good amount of the time. I also had a function for determining my gun power when I would fire. If I recently had three or more successful bullets then I would always shoot at full power, and conversely, if I had been missing ten or more times, I would always shoot at low power. If the target was too far away I wouldn't fire until I was forced to fire. And of course my victory dance is far superior to anyone else's :)

Download my robot, BottomDweller, here

Stats:

• RobocodeBracket.doc
• RobocodeProducerStats.xls

Some coworkers and I planned a competition amongst the four of us. We found a relatively cheap remote control car that we could be able to drive six at once. The arena was our work parking lot. We would start on the perimeter of a circle and have to drive to the middle to pick up a velcro covered tennis ball. You would have to pick up the tennis ball, and drive it back to your base to score a point. Then everyone would reset and we would start again. We pretty much continued this until we started to run out of batteries. Part of the rules were that you weren't allowed to have any weapon that could seriously harm another car. That way we wouldn't waste our investment and we could have numerous competitions.

Our first competition was closely won by Brian who's car was clearly the fastest. He hardly added anything to the exterior of the car, making it light and quick. His plastic bottle scoop was very effective, as it was very low to the ground and securely grasped the tennis ball.

Our second competition occurred in the same place and with roughly the same vehicles. I added much more velcro to the front which proved to be very valuable and dual laser pointers for fun. I was able to pick up the ball very easily because of the velcro on my front license plate. I scored so many points that we stopped keeping track and began to smack each other around a little bit.

For the next competition, I'd like to add some sort of flipping weapon. This will definitely be a challenge.

Stats:

• About $15 on additional supplies
• About 5-6 feet of velcro