Friday, May 24, 2013

The Evolution of My Mousetrap Car Design

If there is a kit available for a project, to me it is worth it to purchase the kit. Buying the first Doc Fizzix mousetrap car gave me a familiarity with a working design and something to guage the performance of the mousetrap cars I would design. For my first design I tried some rather different ideas in that the car was constructed from bamboo skewers and used cottage cheese container lids for wheels. This car worked pretty well but the lids can warp from heat and the bamboo structure required additional bracing because the car was twisting. It was my determination that this design would not be ideal for students to build for their first mousetrap car.

My Start with Doc Fizzix Basic Kit

My First Mousetrap Car Design

Current Design I Use for Classes

My next series of mousetrap cars were constructed in a more conventional way from balsa wood and using four CD wheels with faucet washer hubs. This car was used for a College for Kids class and worked pretty well except the lever arm constructed from balsa glued to form a T-structure was not strong enough for kids to handle. Also the faucet washers I had bought in a hardware store did not fit the hole in the CD tight enough.

Balsa Car Used for College for Kids
Balsa Lever Arm Broke for Students

For the next year I used a heavy dowel for the lever arm and I came up with the idea of cutting chunks from tarp straps for the wheel hub. The dowel lever arms did not break but the students had trouble attaching the lever arm to the wire on the mousetrap with hot glue and string. For this summer's class I have the lever arm already attached. Hot glue takes sometime to setup solid, for impatient kids this is a problem. Since last year's class I have also created the chassis for the car from foam cut with a hotwire.

Hub Created from Tarp Strap

Much can be learned from struggling with a design but for a class where there is limited time and no one to help assist the students I find it better to refine the project.  It is my hope that the students will be inspired to create their own mousetrap cars if the first one was a good experience.

Axles Cut from Coat Hanger - cheap

Screw Eye Idea Came from PITSCO Solar Car Kit


Doc Fizzix Website
My Mousetrap Car Article
Quicky Mousetrap Constructions Article

Bill Kuhl


  1. Hi Bill,

    I have been making these cars with my classes for 9 years. This past year I tried to save on buying the PITSCO class kits and have the kids try to improvise a lot of the designs. It certainly made for a diversity of designs but there were several cars that didn't go at all, which was frustrating for the students. Next year I would go back to the kits. I also offer 3" CD wheels in addition to the regular size CDs because I allow them to choose to enter a speed or distance car in the race. I would be happy to talk with you about how I do it and learn more about your project. I use it as a project to culminate Newton's laws, Energy, and Rotation units in an 8th grade physical science class.

    1. Mr. B, Thank you so much for leaving a comment, I sure would like to receive more feedback. In my College for Kids class I am a little puzzled with how hard it is for the students to build a mousetrap even from a kit. Then I think by their age I had built so many model airplanes and had lots of exposure to building projects.

      It does appear that in most classrooms students are on their own to design a mousetrap car. I noticed one video where only one car out of many went more than a couple of feet.

      If the students are to learn the physics of the mousetrap car, I would think it would really help to have one that actually moves.

      I would be happy to communicate with you or anyone else on this. or 507 450-0202

  2. Very Very good and usable post. Thank's to share your experience with us. I will try to remember these tips in my blog commenting task.

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  3. I've been doing these cars for a long time as well. I teach a 9th grade general science course. I like the Pitsco kits the best but they are expensive. I've tried for years to get the parts cheaper. You can save a little by going to multiple sources for parts but you don't save enough to make it worthwhile. I like the standard design that they have and the kit is simple to make and it works extremely well. Two school record holders are just well done stock designs. I give the kid the stock design and parts from Pitsco. If they want, they can modify the design or do something completely different. About half or more of the class stick with the simple design. If done well it works. Board to board fastening I use wood glue or hot glue. I use superglue for wheels on hubs, wheel to axle, etc. The Pitsco kit comes with brass tube for a lever arm. You can substitute and small metal rod. Clothes hanger works well as a lever arm. Just bend it in an L and put it into the spring where the original arm is placed. I also pull all of the latch mechanism before I give the trap to the students. This year we went with the much cheaper kelvin design and parts. It isn't as nice of a kit but it is far cheaper.

    I used to use the torsion wheels for a lab to determine the energy stored in the mousetrap.but it is difficult for students to keep them straight and they pull the string sideways and end up pulling the staple out of the trap. I have since moved to wooden protractor with increments in radians instead of degrees.

    1. Thanks for your comments John, I make up the parts for the summer class I teach but it is a lot of work. Now the chassis is made from a foam block instead of balsa.

      I have had some trouble with the mousetraps pulling the staples out also. For my new website I have a new general information article

      Bill Kuhl