Goals of the project
Goal 1 is to have a device eligible to compete in the annual Buffalo Valley Pumpkin Pitch and throw a ~7lb pumpkin as great a distance as possible.
Goal 2 is to involve students of a variety of backgrounds in a fun and exciting design-build experience that is completely separate from their coursework.
Nature of the Collaboration
Nate, as lead, would broadcast upcoming meetings and the purpose of those meetings. Then those interested in that aspect of the project would show up and work, and also take on supporting projects in between meetings. All major design choices were presented to the group and challenged and defended in a friendly way, but one that meant decisions were ultimately well reasoned and assumptions were well founded.
For the design, modeling (Working Model computer software), CAD, coding. For fabrication, woodworking, metalworking, welding.
Saws of all types, drills, welders of two types, CNC mill.
This is an ongoing project, every year, we need something to compete in the pumpkin pitch. This was year three. We start by reviewing the successes and failures of the previous design, and brainstorm from there – will this year be an incremental improvement or a wholesale redesign?
It’s good for the students to build something large with an appropriate level of complexity. They learn how you have to look very carefully at your drawings to see possible conflicts. For example, this year’s redesign added guywires to stabilize the arm. Only after they were installed did it become clear that when the trebuchet rebounded after a throw, the wires acted as a knife on one of the wooden braces. The beam was relocated. In theory, the wire should never reach that far, but in practice, it’s a little different.
There is a model trebuchet at 1/10 scale that was used as the prototype, and many many computer models that were then taken to the overall construction.
There’s the challenge with the guywires mentioned above; there’s also the cultivation of physical and practical ingenuity. For example, the trebuchet needs a trigger. Initially, the “design” of this is “get a trigger!” but upon (strongly encouraged) reflection, the students realize that they need to design the trigger. In general, our challenges are solved by iteration, reflection, and persistence.
2013 Distance Champion, 2013 2nd place accuracy, 1st place tie overall.
2014 3rd place distance
Both Buffalo Valley Pumpkin Pitch
Student skills in woodworking, project planning, safety, and self-efficacy with tools increased
Innovations, impact and successes
While the result is fun, the important part of this project is the process. Designing, planning, building, and using a device that can throw a pumpkin 200 yards is a thrill for everyone involved.