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Cub Scout Pack 341

Pinewood Derby
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PWD - Car Construction
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Uniform - Class "B"

Theme for 2005 is "CARTOONS"

Car Construction
 
Here is a ten step plan for constructing a car. Read the entire page before you begin.

There are always some kids, young and old alike, who want to perform the steps in a different order. Try to resist this temptation. Also, be patient and spend adequate time on each step of the process.

Building a Pinewood Derby car is like many things in life. If you do things out of order, or if you make mistakes early in the process, it's sometimes difficult to recover.

 

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. The diameter of the axles in the new kit is 0.088", for which a #44 drill bit (0.086") is a good fit.

Step 3: Cut out the car body.

You'll probably need a handsaw, jigsaw, 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 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: Paint and detail the car body.

Apply a number of thin coats of paint, followed by a number of thin coats of clear finish. Add decals and/or stickers.

Step 7: Prepare the wheels and axles.

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, then polish with toothpaste, 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 5.0 ounces as you can without going over.

Step 9: Install wheels and axles.

Again, the straighter, the better. Your car should be able to roll straight on a level surface for a reasonable distance.

Step 10: Lubricate wheels and axles.

Add lots of graphite and work it into the wheels and axles. Do this often, right up until registration on Race Day.

Some Miscellaneous Construction Tips

Avoid narrow, pointed noses. They are legal, but cars like this are 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, Clarence. 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 something similar instead.

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, my personal preference is 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.

Check out your car before Race Day. Have your car nearly complete by Trials Day. On that day, you'll be able to fine-tune your car, weigh it, measure it, and even race it a few times. By the end of Trials Day, your car should be ready to go!

 
Cub Scout Pack 341 - Louisville, Kentucky
Mohawk District, Lincoln Heritage Council, Boy Scouts of America