Making a Mousetrap Car

Objective: Create a basic understanding of how mousetrap cars function and give a jumping-off point to create higher quality ones.

Intended Audience's: K-12 engineering students

STEL's:

Contexts

- Energy and Power: In order to work, the mousetrap must provide thrust to the car

Practices

- Making and Doing

- Optimism: There are parts of this project that are easy to make mistakes with and it is important to not let that get to you

- Creativity: This project is intended to be a starting point and to promote creativity in making a better version

Core:

- Design in Technology and Engineering Education: This is a common project for young engineering students and can be a great practice in optimization and testing

Whether you are an engineering student or just someone who enjoys making devices at home, mousetrap cars are a great starting point. Something that is great about mousetrap cars is that they are very open to experimentation and customization. For this project, we will be making a very basic version of one in order to give you a starting point on how they work.

Materials:

• 1 wooden snap mousetrap
• 2 wooden dowels
• 4 eye hooks
• Wire or string
• Foam core board
• Duct tape
• Cutting board
• Utility knife

Total Cost: approx. $10.20

1. With the help of an adult, use the foam core to cut out four wheels, being sure to make them the same size. Optionally, you can make the front wheels smaller than the back wheels.

2. After finding the exact middle of the wheels, create a hole approximately the size of the wooden dowels

3. Still using the foam core, cut out the chassis of the car, making sure to have enough room for your mousetrap. I recommend making the chassis two layers thick in order to improve stability Optionally you can use wood or heavy cardboard as an alternative to the foam core.

4. Making sure to line them correctly, mark each corner of the chassis with where the four eye hooks will go.

5. On the back end of the chassis, cut out a roughly one inch long by two inches wide divet over where the back axel will be.

6. Duct tape the mousetrap to the chassis, with the snap bar resting towards the front of the car. Optionally you can remove the holding bar and catch from the mousetrap using pliers, as these parts are not needed.

7. Screw-in eye-hooks, again making sure that they are lined up correctly.

8. Slide the wooden dowels into the eye hooks, making them into axles.

9. Place duct tape on the ends of both dowels in order to help secure the wheels.

10. Place wheels.

11. Using the string or wire, tie one end of the string around the snap bar of the mousetrap. Without allowing much give tie the other end of the string around the back axle.

10. Place wheels.

11. Using the string or wire, tie one end of the string around the snap bar of the mousetrap. Without allowing much give tie the other end of the string around the back axle.

Having now fully assembled your mousetrap car, the next thing to do is to make sure it works. Pull back the snap bar of the mousetrap to where it would be if you were to set it. While carefully holding the snap bar, wrap the string tightly around the back axle of the car until the string is taut. If built properly, when you place the car on a flat surface and release the mousetrap, the mousetrap will slowly release and unwind the string on the axel. This slow unwind will cause the tires to rotate and propel the car forward.

Here are some of the problems I faced when learning to build a mousetrap car.

1. Make sure the dowels fit loosely within the eye-hooks. If the dowels are too big or the eye-hooks too small, the wheels of the car will not be able to rotate freely.
2. Make sure the wheels are as close to round as possible and that the holes for the axel are centered well. If they are not just right, it may cause the mousetrap not to release properly and the car will standstill.
3. Finally, this design is very basic and can be improved upon in many ways. This design will not win you any competitions but is instead designed to teach you how mousetrap cars work in an easy and inexpensive way. This design serves as a starting point and can easily be improved upon with the use of better materials and tools.