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Trebuchet

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Trebuchet

Universal Remote

Westhampton Library Maker Club

A trebuchet is a type of catapult that uses potential energy stored in a large counterweight to throw its payload. They were featured prominently in the video game Age of Empires 2, which my cousin and I played for many hours when we were younger. We decided to take that interest to the real world and build one of our own.

Related info:

Design

The trebuchet is an older project of mine that I built while I was in high school. It went through a series of design iterations to keep it from falling apart and to try out some different ideas.

Version 1

It all started a long, long time ago with a basic design. I really didn't do that much research–other than playing video games and watching movies–so the original was just something I put down on paper one day while cogitating about it. To begin the construction, I slowly started gathering scrap wood wherever I could find it and cutting it out. After a few months of working on the weekends, the frame was all done:

For scale, here is me standing on top:

I wasn't really sure how to build the throwing arm and the axle, but I felt like the arm should probably be one solid piece from the counterweight all the way out to the sling. Also, I was planning on making the axle out of wood. That meant that I would have to attach separate pieces on either side of the arm. This wasn't the best idea I ever had. Regardless, we secured the two axle pieces to the arm by reinforcing it with two steel bars and a few long bolts going all the way through the axle pieces:

The original sling was made out of rope and a piece of denim jeans, secured by string and duct tape. This was one of the first pieces to fail on the original trebuchet. The counterweight was a big wooden box that we had sitting around, connected to the arm with a chain. The box was strong enough that we were able to fill it entirely with rocks and pour sand in the cracks. It made for a good counterweight that could be adjusted as necessary and (fairly) easily removed and transported.

Version 2

In an effort to test out a few upgrades and give the old flinger some new life, I took it down and used the parts for a new, slightly different version:

There were a few upgrades in version 2.0:

  • Reinforcements for the counterweight box, which had started to fall apart
  • A new sling that could withstand more of a beating
  • A solid metal axle
  • A set of wheels

The biggest upgrade was the wheels. The other changes were basically just reinforcing the parts that had broken in the last version, but the wheels were actually intended to increase the trebuchet's efficiency. I got the idea after doing some more research, especially watching a special program on NOVA.

In version 1, I had simply connected the two uprights that made up the frame with a piece of wood and a couple nails. If I was going to put the entire machine on wheels, however, I was going to have to make a much more rigid structure. Also, because the old version was so vertically oriented, I had to shorten and widen the new design to prevent tipping.

Build Log

Here's what the original looked like when it was done (ready to fire):

Here it is mid-fling:

The original design basically just worked great. I threw rocks, I threw watermelons, I even tried a shotput. The trebuchet wasn't quite powerful enough for the shotput, so it threw it straight up and was nearly destroyed when it came back down. It was a lot of fun to show to family and friends:

  

The original trebuchet had a good run and we had fun using it at the annual Fall Festival in Westhampton, but then it sat around for a while and started to fall apart. In fact, it did some serious damage to itself from all that flinging:

Version 2

Because I already had a lot of the wood and I was simply reinforcing some of the other parts, the new design didn't take too long to build. In fact, finding some cheap wheels was the hardest part. Eventually, I got everything put together:

As promised, the wheels helped it throw further than before despite being slightly smaller. The trebuchet again saw a great time throwing stuff at the Fall Festival and lived on for a few more years.

August 29, 2015

The trebuchet has once again fallen into disrepair and been turned back into scrap parts. The only piece remaining is the throwing arm:

The trebuchet was a special project for me. It was the first project on which I embarked where I really was able to accomplish something big. It taught me that the most important part of doing something extraordinary is committing yourself to an idea. Also, there were a lot of people involved in this one, both in building it and watching it throw pumpkins high into the sky. Perhaps it will inspire someone to build their own someday…