Rat Trap Car




Introduction: Rat Trap Car

About: Stuff is on KI.

This project was inspired by LarrySDonald's Mouse Trap Car. I give him full credit for the idea. Anyway, this is a very similar thing except with a twist. My car is made with a rat trap instead of a mouse trap. I had some knex lying around and I thought that they could make great wheels and axles. This car goes pretty far and fast so be careful. You also need to be careful of the rat trap because it is on a hair trigger and can release at any moment. I take no responsibility of damage to any property, body parts or animals hehe. Make sure nobody is in the path of the car when it is being launched.

Let's get started!

Step 1: Gather Materials

To build the Rat Trap Car you will need the following:


1-rat trap
4-eye hooks
10 inches of fishing line


4-large knex wheels
4-grey connectors
4-tan connectors
2-red length rods


Drill bits

Step 2: Mark and Drill

Mark 1/2 inch marks from the edge on both sides of the trap

Drill two holes using the 5/64 drill bit on the 1/2 inch marks you made on both sides.

Step 3: Insert Eye Hooks

Screw in the eye hooks into the four holes you made in the last step. Make sure that the hooks are perpendicular to bottom of the trap

Step 4: Front Axle

Now its time to make the front axle. Get one of the red rods and put one grey connecter on the end. Next slide one of the wheels on and snap in a tan connector behind the wheel slide this into the whole to lock the wheel to the rod. Now slide the axle through on of the eye hooks on the front end (the end with the bar down when not in use) Next put the other end of the rod (the one without the wheel) through the next eye hook. Put the second wheel on using the method above. Now your done with the front axle.

Step 5: Rear Axle

The rear axle is the same as the front but the rod needs a hole driled through it. Use your 1/64 drill bit.

Step 6: Fishing Line

Now get your fishing line and measure out ten inches and cut with your scissors and burn the end with the lighter. Tie one end of the line onto the main arm of the trap. You should have about 9 inches of line on the other end.

Step 7: How to Launch

First you need to put the long end of the string through the whole drilled in the knex rod. Next, spin the rod backwards (on the trap there is a rat, the rat's nose is pointing in the direction you want to spin the rod in). When the string is taught and you cannot turn it anymore without pulling back the arm, pull the arm back and spin the rod again until you have used all the string. Now arm the trap as you regularly would. To trigger the trap get a long object like a ruler or something and tap it and quickly pull away.

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    Question 3 years ago on Step 4

    Hello, did you find the knex wheels, gray connectors, tan connectors, and the length rods?


    Answer 3 years ago

    Obviously. Thats why he uses them in the pictures.


    6 years ago

    Dear bakenbitz, I have to do a project in physics where we have to make a homemade car that has to go up a 23 degree ramp without using chemicals or electricity. I thought this car would work, but I'm just wondering, do you think it will be able to go up the ramp?

    CraZeD MuSiCiaN

    Does this design get both distance AND speed??? or does it just get one or the other? o.0


    11 years ago on Step 7

    man this was so simple yet really well written, thanks heaps and keep writing :D


    12 years ago on Introduction

    how can you calculate the force of the spring?? or the force that the car is released


    14 years ago on Introduction

    I've found it to work even better if you use a broken rubber band instead of a string.

    An Villain
    An Villain

    Reply 13 years ago on Introduction

    that really depends on your point of view, all of the rubber bands that i need whole are broken


    13 years ago on Step 1

    where do you find knex wheels?


    13 years ago on Step 7

    how far did this go