This instructable will help you build a self-propulsion mousetrap car. The car uses physics and engineering concepts such as pulleys, levers, and springs to convert potential energy to kinetic energy which moves the car along.
Step 1: Supplies You'll Need
- (1) Mousetrap
- (1) 6" x 1.5" x 0.5" Board (Body)
- (2) 18" x 0.5" x 0.5" Stick (Legs)
- (4) 2.75" Diameter mason jar lids (Wheels)
- (2) 10-24 x 3.5" All threaded rods (Axles)
- (8) 10-24 Nuts
- (4) 1.25" Finish nails
- (4) 0.5" Finish nails
- (1) 12" Wire coat hanger
- 24" Fishing line
- (2) 3/8" or 10 mm Wrenches
- Electrical Tape
Note: Each leg has previously drilled holes located 1" from each end using 13/64" drill bit. (see photo)
Each wheel has previously drilled center holes using 13/64" drill bit. (see photo)
One axle has previously drilled hole. (see photo)
Step 2: Label Front and Back of Mousetrap Car
- Label FRONT on one end of leg.
- Label BACK on opposite end of same leg.
- Repeat steps 1-2 on remaining leg. (Note: These will be will used for orientation during assembly.)
Step 3: Nail Legs to Body
- Measure and mark 2 inches from FRONT leg end.
- Align body with 2 inch mark on leg. (see photo)
- Nail leg onto body using two nails.
- Repeat steps 1-3 for remaining leg.
Note: Alignment is crucial for a straight axle. Before nailing the second leg, make sure leg axle holes are lined up by sliding the axle through the leg holes. This will ensure you have a straight axle.
Step 4: Nail Mousetrap to Body
- Orient mousetrap hammer and catch end towards FRONT of mousetrap car. (see photo)
- Center mousetrap on top of body. (Note: There will be some mousetrap overhang onto legs.)
- Nail mousetrap to body using 0.5" nails. (see photo)
Step 5: Wheels and Axles
- Screw one nut onto axle with hole. (see photo)
- Slide one wheel onto axle after nut. (see photo)
- Screw second nut onto axle after wheel.
- Tighten nuts using wrenches. (Note: Make sure nuts are snug and secure around wheel, otherwise you will have a wobbly, non-funtioning wheel. )
- Slide open end of axle through both BACK leg holes. (see photo) (Note: The axle with the hole must go through the BACK legs!)
- Repeat steps 1-4 on other end of axle. (Note: This will be for the second wheel on the same axle.)
- Repeat steps 1-6 for FRONT of legs using remaining axle. (Note: This axle WILL NOT have a hole.)
Note: Once assembled, there should be a small gap between the nuts and the legs. This will enable your wheels to move freely.
Step 6: Wire Arm
- Wind tape around wire arm straight end to mousetrap hammer. (see photo) (Note: Be sure the wire arm and hammer are tight and secure to ensure stability)
- Tie one end of fishing line to wire arm hook.
Step 7: Final Set-up
- Push mousetrap hammer towards BACK end axle. (see photo)
- Set the mousetrap. (Place holding bar under catch.)
- Orient mousetrap car BACK end towards you.
- Thread small amount of fishing line through hole in BACK end axle. (see photo)
- Key Step! Wind wheels towards you, top to bottom, until fishing line is completely wound. (see video)
Step 8: Ready, Set, Go!
- Place mousetrap car on flat, long surface.
- Tap the catch. (see video.)
- Mousetrap car will begin to move itself. (Note: Due to friction, you may need to give the mousetrap car an initial nudge.)
- CONGRATS!!! YOU DID IT!!!