Pinewood Derby Car Construction Method

Step 1: Design the car.

On a piece of white paper, sketch the side and top views of your car. Include in your design where the axles will go and the locations in which you will place additional weight. Copy this design onto the wood block.

(It's probably best to perform this step while not in the presence of any tools. Many have succumbed to temptation at this time.)

Step 2: Drill the axle holes (or drill out the pre-cut grooves if you are using them.)

Get these as straight as you can. Use a #44 drill bit (0.086") for best fit.

Step 3: Cut out the car body. 

You'll probably need a hand saw, jig saw, or coping saw for this, and possibly a chisel and hammer. It's a good idea to cut, chisel, or drill out areas for additional weight at this time.

Step 4: Shape and sand the car body.

Sandpaper is a must here, of course. A small wood rasp can also be useful. Shaping, smoothing, and detailing can also be done with a Dremel (or similar) tool. Attach any decorations, such as driver, steering wheel, fins, spoilers, etc., at this time.

Step 5: Preliminary length and weight check.

Measure the length of your car and make adjustments if necessary. Weigh the body, axles, and wheels together. Securely attach weight (5-minute epoxy is good for this) to bring total to 5 ounces.

Step 6: Seal, Paint and detail the car body.

Before you start painting, it is important that you seal the pine wood before you apply any paint.  Sanding Sealer (available under our Finishing Supplies), seals the wood and will give you a smoother paint finish.  You should apply 3 – 4 coats of Sanding Sealer and then use the 220 grit or higher sandpaper to smooth out the finish.  Use a clean damp cloth, brush or canned air to remove any wood dust before you start painting.

Then apply a number of thin coats of paint, followed by a number of thin coats of clear finish. Add decals and/or stickers then add another 2 layers of clear finish on top of the decals.

Step 7: Prepare the wheels and axles.

Self-Preparation

Sand away the mold projections from the wheels and wheel hubs then polish them. Place each axle in a drill. Remove the burrs from underside of the axle heads with a small file. Smooth the axles with wet, fine grit sandpaper, and then polish with, wet pumice, or jeweler's rouge on a strip of cloth.

Step 8: Final length and weight check.

Measure your car's length again and, if needed, make adjustments. Weigh the body, axles, and wheels again. Adjust the weight to as close to 141.75 grams or 5.0 ounces as you can without going over.

Step 9: Install wheels and axles.

At this point, your car should be able to roll straight on a level surface for a reasonable distance. Find a very flat surface like a piece of glass or a smooth countertop.  Mark a straight line down the surface and roll your car gently.  You will be able to see if it pulls to the right or left.  To fix any drift, you may have to adjust front axles by bending them very slightly and then trying different positions until your car rolls as straight as possible.  Weight that is distributed unevenly on the car can also cause it to drift. 

Step 10: Lubricate wheels and axles.

A lot of building tips state “Add a lot of graphite”, this is just not true.  Too much graphite packed into the hub will bind the wheels and cause the 1^st and possibly 2^nd heat to have slower times until the excess lubricant works itself out.  It is better to put a little in at a time and spin the wheels two or three times to coat the axles and the inside of the hub.  Repeat this 3 or 4 times the night before you turn your car in to registration.  Just before you turn you car in, add a little more graphite into the inside hub of the wheel and underneath the nail head and work it into the wheels.

Some Miscellaneous Construction Tips

• Avoid narrow, pointed noses. They are legal, but the cars may be difficult to stage at the starting line. Also, cars are detected as they cross our finish line because the nose of the car blocks an infrared beam. Such a car may not trip the sensor correctly.
   

• Check your clearance. It is very tempting to simply screw those flat weights to the bottom of a car. But if you do, your car will likely scrape the center guide strip on the track. You must inlay the flat weights if you're attaching them to the bottom of your car.

• Drill the axle holes before you cut out the car body. This was stated earlier, but it bears repeating. It's easier to drill a good hole into a squared block of wood than into a car-shaped block of wood.
   

• Don't epoxy the axles to the car body. You'll never get them out if you have to make a last-minute adjustment or an emergency repair. Use wood glue or my favorite, a high-temp glue gun. 
   

• Apply many thin coats of paint and finish. Your car will look better if you apply 10 thin coats than if you apply 2 thick coats. Also, use brush-on paints over sprays. They're easier for a Scout to handle and they're less messy.

• Check your car's length early on. This was also stated earlier and it also bears repeating. Better to trim it sooner than later.