How to Assemble a Mouse Trap Car

The potential energy stored in the spring makes a mouse trap an effective engine for a model vehicle.

Racing mouse trap cars is a great way to combine construction skills, scientific theory and artistic flair. Races are most often held by organizations such as the Boy Scouts or Physics and Engineering clubs, but the simple, inexpensive nature of mouse trap cars allows just about anyone to set up a race. Simply challenge two or three friends to a race, and start building your mouse trap car.

Things You'll Need

• 2-inch by 3-inch block of balsa wood, true to square at all corners
• Ruler
• Pencil
• 4 eye hooks
• 2 lightweight 6-inch axles
• 8 rubber washers, sized to fit the axles
• 4 1-inch wheels
• Wooden mouse trap
• Stiff wire
• String
• Wood paint or hobby decals (optional)

Instructions

1. Measure 1/2 inch from the top and bottom (the short ends) of the balsa wood. Make a light mark with your pencil. Measure 1/4 inch from each side and mark those. The four intersections are where you will place your eye hooks. Use a ruler to precisely measure from the bottom of the wood to the mark where you will place your first eye hook. Note this measurement, then measure from the bottom of the wood to the mark on the other side. If the measurements are exactly the same, you know the two marks are even. Adjust as needed. If the axle is not even, the car's alignment will be off and the car will pull to one side. When your marks are even, screw a pair of eye hooks into the balsa wood at your final marks at one short end. Screw each into the wood until the loop is flush with the wood. Repeat with the remaining two eye hooks on the opposite side of the wood.

2. Thread the axles through the eye hooks. Place one rubber washer on each side of the first axle, close to but not touching the eye hooks. Thread two of the wheels onto the axle. Place two of the remaining washers on the axles to hold the wheels in place. The washers should not touch the wheels. Repeat with the second axle.

3. Glue the mouse trap to the top of the car. Allow the glue to dry thoroughly.

4. Cut and bend one end of a six inch length of wire into a hook around the spring arm of the mouse trap. Bend the other end of the wire into a loop.

5. Cut a 12-inch length of string. Tie one end to the wire loop. Coil the other end around the back axle of the car, in the opposite direction that you want the car to move.

6. Arm the mouse trap. Release the spring to propel your car and see how fast and how far it can go.

7. Paint or attach decals to your car to add personality and flair.

Tips & Warnings

• Experiment with the design of the car to increase its speed or distance. Lowering the overall weight of the vehicle will increase its speed. Increasing the axle-to-wheel ratio will improve distance.

• Mouse trap car kits are available at major hobby stores, and will save you the time of finding materials.

• Use caution when working with the mouse trap to avoid getting your fingers caught.

References

• Mouse Trap Car
• Fast Speed-Trap Racer
• Long Distance Traveller
• Drexel University Mouse Trap Car Competition