Wednesday, February 4, 2009

Concept to Completion: Building a Pinewood Derby Car

This past weekend, my nephew Luke participated in the Boy Scouts' Pinewood Derby Race. He asked me to help build the car. Now, I was never a Boy Scout, and I had never built a pinewood derby car. But, I did take shop in the 7th and 8th grade and participated in the Technology Student Association (TSA). I had to build many CO2 powered cars that are very similar to pinewood cars. Pinewood Derby RacerNeedless to say, this was something I wanted to help with.

Prior to our first construction session, Luke had drawn out the concept on a sheet of notebook paper. We modeled the car as closely to the design as possible. After transferring both the side view and top view design patters to the block of wood, we used a band saw to cut out the pattern. Once we had the rough shape of the car, we used sandpaper blocks and a Dremel tool to smooth and polish the shape.

During our next construction session, we added weight to the car and applied the paint job. Hobby Lobby actually has a section for building these cars, and they sell custom weights. Regulations say the car cannot weigh more than 5.0 ounces, so our goal was to get as close to that weight as possible. Ideally we wanted 4.95 ounces to account for a margin of error between our scales and the official weigh-in scales. The stock version of the car including wheels, but no additional weight, registered 4.35 ounces. After adding recessed weight to the bottom and accommodating for wood lost in doing this, we got the car to weigh in at exactly 4.95 ounces. Overall, we probably invested 7 hours in the car's construction.

TrackThe day of the race, I saw so many creative concepts. The best had to be one shaped like a Nintendo Wii-mote. The track had three lanes with an electronic finish line. Race information was fed back to a computer which would indicate the winner and the scaled MPH of each car. Luke's first race was heat 2. Unfortunately, we got smoked by the other two cars. We ran 192.5 MPH and they both ran over 199. However, in the end, the two cars that beat us from that heat were two of the fastest in the competition. We won first place in every other heat. In the end, we had a race car that was in the top 10%. On average, our car ran around 195 MPH consistently.

Wii CarOverall, I think it was a good experience for Luke. He learned how to shape a piece of wood into any design by using patterns. He even learned how friction and momentum impact the success of the race. This was our learning year. Next year, we'll be back with a much faster 200+ MPH car.


  1. Congrats!!!!
    Ryan and Jim's nephew both have done the cars with Boy Scouts....I went to one of the races last year at the YMCA in Montgomery. It was fun!! And yes, they are very competitive in designing and racing these cars. I saw that the Dads were more interested than the kids. Funny!

  2. Ha that Wii-mote is tight. I remember competing in one of those races. I lost bigtime, of course.