Trebuchet Project

Underlying Concepts

A trebuchet is a launcher that uses a counter weight to throw objects. Basically my goal was to build a trebuchet that didn’t look hacked together and somewhat worked. The design of a trebuchet is simple; you need an arm that can rotate around an axle, suspended with weight on one end and an object to fire on the other. The weight of the counter weight is more than the object being launched so that when the trebuchet is shot, the weight will pull down one end, raising the other and launching the object. Logically my design should work it has everything it needs to work; the trebuchet itself isn’t too big so the counter weight should weigh enough. I think where the fulcrum of the arm is placed is a good spot for lots of leverage so the object should launch okay. This project is relevant to the real world because like in the real world, engineers solve problems. Sometimes they solve problems using designs and that’s a key concept in this assignment. Math and science are also used in this project; geometry definitely has a role on how sturdy the design is and how much stress it can take, or you can use physics to get the best fulcrum point.

Fabrication Decisions

My design is fairly simple, I felt that simplicity might be the best option since it’s so small. I went to Michael’s for most of my material, the rest I had laying around or used from the FIZ. My material list consisted of four 2-foot wooden fence pieces, one foot of 2 by 4, cardboard, a pencil, wooden dowel, wires, a chunk of 1 by 1, screws, staples, hooks, and glue. My design wasn’t specific, I just sort of made measurements as I went. The block of 2 by 4 is the base and it was around a foot long. Knowing this I tried to keep my design around the same size of the board. First thing I did was make the supports. I decided 10 inches high would be appropriate so I cut two 10 inch pieces of fence and screwed them both straight up on one end of the block of 2 by 4. Next I used the scrap from the two 10-inch pieces to make the diagonal supports. They both were at a perfect equal length so they lined up perfectly with the design I had in mind. The only problem was there was a gap since I was overlapping the supports. To fix this I cut off two 2-inch pieces of fence from the other pieces and used them as a spacer so the diagonal support would fit. After screwing those in, I lined them up the way I wanted (i used a right triangle design thinking it would be stronger than the other types) and drilled a hole the same size as the dowel I had. I test fitted it and everything worked out, I then made the arm. I glued two pieces of fence together and used clamps to make it bond better. After about an hour or so I took the clamps off and drilled two holes in the arm: one where the fulcrum would be and another where the weight would hang from. The holes I drilled where two sizes bigger than the dowel I had so that the arm would rotate around the dowel. I put the arm on the base and glued the ends of the dowel to make sure it wouldn’t come loose. Next I cut and screwed a piece of 1 by 1 onto the base piece and put a hook in it. Then I put a hook on the bottom of the arm so that I could fit a pencil through both holes acting as a trigger. After that I made a bucket out of cardboard and stapled it together, then to the end of the arm. Finally I wrapped up a bunch of thick gauge wire as a counter weight and tied it to the other end of the arm.

Safety Precautions

I worked on most of my project in the FIZ which has it’s own set of rules and guidelines. For example a safety standard I had to follow was wearing safety glasses. Safety glasses were important because other things were going on in the shop while I was working; I didn’t have to be doing anything dangerous to risk injury. I needed to be aware of what was around me and also what I was doing. I wore safety glasses because of the environment, but also because I drilled and cut things to make the project. When I drilled, it was better to clamp things down so I didn’t lose control of the piece. It was smart to do little things like putting tools out of other people’s way or putting them away so that there wouldn’t be any accidents. It was also a good idea to use earplugs, which the FIZ provided along with the safety glasses, because of loud noises like the chop saw or the power sander that others might be using. I