Mark Rober, a former NASA engineer, is the source of a very popular YouTube video that explains how to use science to create a fast pinewood derby car.
Mr. Rober very fun video demonstrates the rail rider method that we are attempting to follow again this year.
We’ve polished our axles and waxed our wheels. Now it was time to bend, or cant, our axles.
1 ) Use the axle bending tool.
Using a regular hammer and the axle bending tool, we bent the front right axle (the wheel that will be riding the center rail) approximately 1.5 degrees. It is important to place a mark at the 6 o’clock position on the axle head prior to canting this axle.
6 o’clock mark
The left front axle (the wheel that will not be touching the track) is bent 2.5 degrees. This isn’t an exact measurement, but we’ll trust the tool.
2) Insert the Wheels.
Instead of canting the rear axles, we simply used a special needle nose pliers to insert the axles at an angle. The wheels were inserted to the point where they nearly rub against the car body.
The front axles were installed using the pliers. The front steering axle was inserted with the mark at 6 o’clock, whereas the opposite axle was turned until wheel does not touch the ground. The steering axle as a bit more lateral play than the rear axles to keep the wheels from fighting one another.
As the video demonstrates, we achieved the desired result of the front wheel angled top out and the rear wheels bottom out.
3) Attaching Weight
We starting using flexible, stick on weight available from any of the retail stores last year. It is super easy and fast to get the car up to weight. Connell’s car was a bit under weight, 1.8 oz even with the wheels!
I took a 2oz weight strip, plus an additional 1.2 oz to get it up to the 5.0 oz maximum weight.
4) Tuning the Wheels
Like the video pointed out, the canted front wheel provides an easy point to tune the car to move in the desired manner. We set up a board in our basement to test the drift (as noted in the video).
We used the pliers to adjust the axles to get the drift to the point where the cars look OK. Graphite is the universal lubricant for pinewood derby cars, but years of getting graphite everywhere showed that the more expensive Krytox oil is well worth the cost. A drop or two on each axle does the trick.
Less than two weeks until the derby. We’ll play around a little bit more, but I think we are ready.