In Spring 2016, I took a class in which we worked in teams of four to design and build a small scale dragster. The car had to be able to climb a hill, shift gears, and activate brakes.
We 3D printed a lot of parts including the wheels, battery mounts, motor cap, and drive pulleys.
Here’s the car in the early stages. I cut a prototype frame out of delrin on a laser cutter before the final aluminum frame was cut with a water jet. The prototype frame helped us ensure all of our component spacing was ideal.
First prototype frame
My task was to design the transmission. I wanted to do something different than some of the things done by students in previous years so after a lot of thought and looking at various powertrains, I came up with a dual idler setup.
The lever is spring loaded, when the dragster reached the top of the ramp, a pin releases and the idler releases tension on one belt and tensions the other belt.
We designed a disc brake using a magnet and steel disc. A lever pulled a string which caused the magnet to rotate and grab the steel disc.
To save weight, I replaced the steel motor cap with a 3D printed one. This also helped with some stability issues we encountered.
Our design won the design competition. As a result, our Professor gave me the opportunity to design and build a vacuum mold to build covers for the cars. Visit the vacuum mold page to find out more.