Mousetrap Powered Car

This project is from my upcoming book, Making Things Move.  In it, we’ll use the energy that a torsion spring can store to power a small car. Refer back to this main figure as you step through the recipe to build your own!

I built about 60 of these simple kits to show people how to make and race mousetrap powered cars at two events run by artist  Aki Sasamoto, co-director of Culture Push.  The first was a DOING workshop where I taught a small group of 10 professionals from other fields. The second was a larger scale public event with 100 people called Storm Your Brain, held at the Whitney Museum as part of the Biennial.  It's a fun project with just a few simple parts that just about anyone can make.

Step 1: Ingredients

• Mousetrap
• 1/4” diameter wooden dowel
• 2 eye screws that the dowel fits into (like McMaster #9496T27)
• 24" of monofilament (fishing line)
• 2 laser cut wheels (use template below, make yourself, or order from Ponoko.com.  I made these myself on Eyebeam's laser cutter  - one of the perks of being a resident!)
• Wooden paint stirring stick
• Ping pong ball
• Multi-tool with knife and file
• Duct tape

Comments

[Scubabubba]

Next we need someone to I'ble a car-powered mousetrap.

[Nicola Tesla]

so the mousetrap is powered by the car????

[vivekdutta]

how big does wheels have to be and how fat? does it matter how heavy the wheel is?

[dustynrobots]

Excellent question. The CD size works well, and doesn't have to be thicker than that if you get get it on the shaft straight. Smaller wheels will spin faster but cover less ground, larger wheels will be slow starting but cover more ground. So if you're racing for speed over a short distance, small might work, if you're shooting for max distance, slightly larger wheels could work. Heavier wheels just have more inertia so will resist getting started, but once they are going will help keep your car rolling for longer. It really depends a lot on your surface too and the friction.

[aliceisavamp]

it wold be nice so please let me know dustynrobots

[aliceisavamp]

it would be nice if you could make it so it is free

[Mr. Potato Head]

Do you suppose this design could be expanded to power an actual car? I'd love to have some sort of alternate vehicle that doesn't waste fuel and hurt the environment. This would be a way cool solution! Is there a way to calculate how many mouse traps I'd need?

[cook$]

I've never built one, but does the dowel unroll the line, then re-roll it?

[dustynrobots]

Good question. I tie the knot around the axle loose enough that when the line unravels it will just slip. However, if you tie it tight, it will unroll the line and re-roll it. The car won't have much momentum at this point anyway so it won't make too much of a difference. I first designed this kit to go about 10 feet, but you can easily get 20 out of it. Good luck!

[cook$]

I was thinking, if you were to push a pin through the axle, shorten your line, and make a loop in the end of it. Hook the loop over the pin and spin the axle until the slack line has been wound up. When the car is triggered, the line will unroll as per usual, and when it has fully unrolled the loop will slip off the end of the pin. Hopefully, the car will have enough momentum to move quite far, and won't have a trailing piece of line. Although I haven't tested this or anything, it's just an idea I had. Do you get what I'm describing?

[dustynrobots]

I do! And I bet it would work as long as you kept the pin short enough so it didn't catch on the line as it unraveled. Good call.

[LenBoyer98]

what about putting a little notch in the axel and knotting the end of the line so when it unravels it will pop out of the notch? GREAT instructable!

[cook$]

Excellent! If you ever try it let me know how you get on!

[SdaMaster]

we made one of these for a science olympiad competition and we built a balsa frame with four wheels and then wrapped half of the line on the axle put it around the cutoff tip of a ziptie and wrapped it the other way so it would go in reverse. The goal was for it to go 7-9 meters and then reverse back to the starting line.

[ac1D]

We used to make those at school. An alternative was to use a rubber band that we would stretch around the axle, so when released, it made it spin and the car would go forward on a longer distance than mousetrap.

[dustynrobots]

I think I know what you mean, but it's hard to picture. You should write up a counter-instructable!

[ac1D]

Unfortually I don't have this car we had to build. It was going so fast that we needed to put elastic on both wheel so they did not spin.

[airsofter1]

You should put up a video of it in action.

[halberdear]

lol ingredients... Your making me hungry!

[korangster]

nice

[Macarena]

This would have been great for me a few months ago when I had to do this for a science project haha :-)