How to build a pinewood derby car
General Guidelines for Pinewood Derby Car Design
The possibilities are endless when it comes to picking a shape for your pinewood derby car. Before you begin, consider the following guidelines:
Avoid designs with a pointed nose. A pointed nose will make it difficult for your pinewood derby car to rest on the pin at the starting gate. It may also cause your pinewood derby car to get bumped around when the pin drops, and it can create problems for electronic timing systems.
Leave enough wood in the rear of the pinewood derby car so you can place additional weight there. You will end up putting most of the weight in the rear of the pinewood derby car.
Make the maximum weight. Your car should weigh 5 ounces. If your car weighs less than that, add coins or other weights.
Be sure that it is very clear which end of your pinewood derby car is the front and which end is the back. In many races, the race officials —- not you -— will actually place each pinewood derby car on the track. Sometimes the officials put the pinewood derby car on the track backward because they can’t tell which end is which.
Choose a design that allows the air to move over and around the pinewood derby car body in a smooth manner. Pinewood derby cars with aerodynamic profiles go faster.
Designing the Ultimate Pinewood Derby Car
You don’t have to strive for the “ultimate pinewood derby car” to build a fast car and have fun competing in your pinewood derby. But if you and a helpful adult are willing to put in the extra time and effort, these tips are for you.
Bake the Block: Start with your block of wood, and before you do anything else, bake it in the oven at 250 degrees for around two hours to remove moisture and make it lighter.
Create the Design: Select a fast design. A rectangular car is not an aerodynamic design. The most basic aerodynamic design is a simple wedge. If you don’t have time to design a complex car, a wedge will work just fine.
Cut the Design: Draw the outline of your pinewood derby car on a sheet of paper, cut it out and attach it to your block of wood. Use a coping saw or find someone with access to a band saw to make this easy. Check around with the older den leaders or the Cubmaster in the pack as they will most likely have ideas for you.
Determine Weight Placement: A heavier rear increases speed. Add weight to the rear of your pinewood derby car. Remember to make your car as heavy as the rules allow.
Create Glue Holes: Glue the axles firmly in their holes to ensure that they stay perfectly placed.
Sand the Pinewood Derby Car: Make it smooth to reduce friction.
Lubricate the Wheel Well: The less friction between the body and wheel, the better.
You will find online other “tricks” of the trade to make your car go faster. Here’s a warning – we don’t allow extended wheel bases, three wheels touching, or individually molded tires or axles in our races. All of the cars go through a check in process to make sure the cars use the components out of the box. The goal is to have fun and create an opportunity for you and your scout to have some quality time together.
Choosing and Polishing Your Axles and Wheels
The quality of your axles and wheels may be the most important factor in building a fast car. Here’s how to choose and polish your axles and wheels.
- Start with a set of raw axles.
- Make sure your axles are straight.
- To tell which are straight and which aren’t, mark each axle with a marker about 1/2 inch from the pointed end.
- Have an adult clamp a power drill into a vise, a device that will hold it perfectly still.
- Have an adult help you clamp each axle into the drill at the location you marked in Step 3. Have the adult turn on the drill.
- Bent axles will wobble as they turn in the drill. Straight axles will hardly wobble at all. Pick the ones that wobble least.
- Once you’ve selected the four straightest axles, use a file or fine-grit sandpaper to remove small burrs and mold marks that can cause friction and slow a car. These imperfections should be removed from both the axles and the wheels.
- Use polishing compound from the auto supply store to polish the wheels and axles. One easy way to do this is to clamp the axles back in the drill and let the drill spin the axle while you polish it.
- When you install the axles and wheels, make sure they are aligned perfectly straight. You can test the alignment of your axles by pushing your car across a smooth floor or table. It should roll in a straight line.
- Don’t forget to add graphite or another dry lubricant to your wheels and axles.
Remember: The No. 1 rule of a pinewood derby is that it’s supposed to be fun. While you should always strive to do your best, don’t get caught up in winning. Just enjoy the ride.