Self-Braking Car

The challenge I created for myself to fit the make it move contest is a self-braking car. The constraints I made for myself were that it had to both propel and stop itself without any interference following the wind up. I succeeded in this challenge using fairly easy to find materials.

4 CDs

carboard

2 popsicle sticks

2 chopsticks

hot-glue gun

2 rubberbands

For my first draft, I took inspiration from a mouse trap car I made last year, instead opting for rubber bands as a means of propulsion rather than the mouse trap. I would utilize the chassis I had already created for the mousetrap by cutting two holes in the middle of the carboard in order to create a place for the rubber band to connect, connecting it from their to the axle. I then realized the impossibility of wrapping the rubber band around the center part, as well as the center of the axle. I then decided to create a 2-thick popsicle stick attachment that would sit in the same area as the center part would have, but hang off of the edges so the rubber bands could be connected to the outsides of the axle.

This picture shows the area were I was planning to attach the rubber bands, as it was already there from the mouse trap car. It also shows how I created the axles, by making small holes out of pieces of carboard and sliding the chopsticks through, followed by the connection of the CDs with more pieces of carboard on either end.

This is how I ended up connecting the rubber bands, using a hot glue gun on both connecting points. By using a hot glue gun to connect the rubber bands to each point, any movement of the wheels past the end of propulsion would cause the rubber bands to tighten up and wheels to stop moving, thus braking the car.

This is the end product. If I were to make any changes to the car in a new prototype, I would wrap the edges of the CDs in rubber bands to create greater friction and prevent slipping of the wheels. Besides that though, I believe this self-braking car fits both the requirements I set for myself and the requirements for the "make it move" contest.