How to Build a Mousetrap Car: Step By Step Directions

Schools and colleges assign the task of building a mousetrap car as a part of science fair projects, because they help demonstrate the application of the various concepts of physics. Besides imparting knowledge, building a mousetrap car is fun.

The list of equipment required to build a mousetrap car, is given below,

• Wooden Mousetrap
• Rubber bands (Two)
• Plywood (4 boards, 16 inches squares)
• Eye screws
• Metal rods
• Drilling Machine
• Scale/ Measurement tape
• Small handsaw
• Vice
• Epoxy glue

Step #1
Before building the mousetrap car, you will have to make certain modifications in the mousetrap. Be careful while handling the mousetrap, as you may hurt yourself. Remove the bait holder of the mousetrap and take out the wire catch (the wire that keeps the mousetrap open) with the help of pliers. You will need this wire catch later, so keep it aside.

Step #2
In this step, you will prepare the assembly for installing the axles for your mousetrap car. Take two eye screws, and insert them at corners of the rear end of the mousetrap. Place these eye screws 8mm to 1cm, from the respective corner. While inserting the eye screws, take care that the wood does not split in the process. Similarly, screw the remaining two eye screws at the front end of the mousetrap. Align the eye screws properly so that you can slide the rods through them.

Step #3
Now, it's time to prepare the wheels for the mousetrap car. Take the plywood boards and draw four circles of equal diameter. The recommended diameter for the wheels is 75mm. You can use a compass to draw these circles. Drill holes with a 3.7mm drill bit in the center of the circles and place the rod through them. Ensure that the rods should not slide easily through these holes and a little force is required to place the rods. Cut the circles from the plywood with the help of a saw. To smoothen the wheels, use a flat file.

Step #4
Take metal rods and cut them into equal length. Use the following formula to find the length of the rod:
Length of Rod = Width of Mousetrap + 2 (Thickness of Plywood) + 5mm
You will require two such rods. Take one rod and mark a cut at a distance of one third of its total length. The depth of the cut should be half the diameter of the rod. Widen the slot with the help of a jeweler's file. The slot should be wide enough to hold the wire catch (the one you removed while modifying the mousetrap).

Step #5
Cut the wire catch to the length of 7mm and file its ends, so that there are no burrs. Take the epoxy glue and fix the piece of wire into the slot you just made. See that the wire overhangs the rod, but on only one side. Leave the glue to dry overnight.

Step #6
Take the rod with the wire and place it into the eye screws at the rear end of the mousetrap. Install washers at the end of the axle. There should be enough space left for placing the wheels. Now place the wheels at the end of rod with help of the vice. In the same way, install the wheels and axles at the front end. Put rubber bands around the rear wheels. Use glue to place the rubber bands properly.

Step #7
Take a piece of string and tie it to the middle of the mousetrap jaw. Make a small loop in the string such that the end of this loop reaches the rear axle and cut off the loose ends of the string. Your mousetrap car is ready.

How to operate a Mousetrap Car
Raise the mousetrap jaw slightly, slip the loop of the string over the wire of the rear axle. Now, move the rear wheels in the reverse direction, so that the string winds itself around the rod. This will open the mouth of the mousetrap. Release the wheels when the jaw is completely opened.

If you want to take part in a mousetrap car race, go ahead and make your mousetrap car with the help of the aforementioned steps.