Pinewood Derby is a hobby that combines the crafts in making a model racing car with the thrill of competing with it. The cars themselves are simple, fashioned from a block of pine with basic axles and wheels, and driven solely by gravity. Putting the wheels on is the most complicated part of the basic assembly, but even so the task is relatively easy.
Examine the axle nails that came in your kit for burrs. They almost always have them, and these need to be removed to provide a good surface for the wheels. Clip them off with nail clippers.
Create a smooth finish on the axle nails, so the wheels can turn with minimum friction. This makes the car faster. Start by filing the de-burred area, and then sand it with sandpaper and a hand block.
Measure your wheels. Add 1/8 inch to their width, and then measure down from the top of the axle nail and mark by that measurement. For example, if your wheels are 1/4 inch, then you need to mark 3/8 of an inch down the axle nail. This marks where you need to stop driving the nail into the car.
Measure and mark the placement of your axle nails on the car. Your Pinewood Derby racing organization may have specific rules regarding axle placement, so consult your rulebook before taking this step. However, make sure you have at least 3/8 of an inch of clearance under the car when you make these measurements.
Drill holes for the axles. The axle nails are easy to bend, so having a channel to tap them into is a great help. Choose a drill bit that is a full size smaller than your nail, however, to leave enough wood to grip the nail.
Coat an axle with graphite to lubricate it and slide a wheel onto that axle. Repeat for all of the other wheels.
Tap an axle with a hammer to drive it into one of the channels you drilled. Stop when you reach the line marked in Step 3. Repeat for the other three axles.