| Pack 373's Pinewood Derby Pages |
| "A little, healthy competition is a necessary part of building strong character." |
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| Car Body |
Once you have picked out your design, the car must be cut out. If you have access to a band saw, scroll saw, or other woodworking equipment, this will be an easy job. Some boys may be quite capable and experienced with hand tools such as coping saws, files, drills, sandpaper, and paint. Please be careful when using power tools. A trip to the emergency room is no fun for anyone!
Examine the axle slots for imperfections, and to ensure they are square with the body. The front of the car is typically the end with the axle slot farther from the edge, but it really does not matter which end you decide to be the front of your car. Axle slots may be “cleaned up” or “squared”, but may not be extended. The wheelbase of 4 ½ inches must be maintained.
Axle slots that are severely damaged or out of "square" may be re-cut on the opposite face of the block. Special designs may require this action to be taken in order to have correct wheel placement. As long as the wheelbase of 4 ½ inches is maintained, you can design your car as you wish. If you have a design that requires 2 inches of wood in front of the front wheels, re-cutting the axle slots would be necessary; placing one slot ½ inch from the rear and the other slot 2 inches from the front, thus maintaining a wheelbase of 4 ½ inches.
Pre-drill your axle slots using a drill press and a #44 drill bit. This will ensure a round hole that is perfectly perpendicular to the body and slightly smaller than the diameter of the axle. Do not trust the depth of the axle slots. Front and back slots may not be the same depth. Always measure accurately before drilling to ensure all four axles will be the same distance from the bottom of the body. If the axles are not all the same height, all four wheels will not touch the track surface.
If you need assistance cutting out your car, please contact your Den Leader immediately. Your local woodcraft shops, hobby shops, or your local High School Shop Class will be happy to assist you in cutting out your designs. Some Packs, such as ours, hold workshops during the months before the Pinewood Derby to assist novice designers, and those who do not have access to woodworking tools. If you choose to do the work yourself, PLEASE SUPERVISE YOUR CUB SCOUT. SAFETY FIRST!
After the body is cut out, take the body, wheels, axles, and weights to the Post Office or grocery store. They will be happy to weigh the cars for you, and their scales are very accurate. Put the body, wheels, and axles onto the scales first. Then add weights until the total weight is close to 5.0 ounces, but not over. You do not have to be exact, but the closer you can get, the better off you will be.
The official scales used on the day of the race may weigh slightly different than the scales used to initially weigh your car, so be prepared to add or remove a little weight. Always have a small piece of weight attached to the underside or back of your car by a screw. On the day of the race, you can easily remove this small weight, or replace it with a heavier piece of weight to achieve the 5.0-ounce maximum weight. Also be sure this removable weight is fully recessed into the body of the car so you do not exceed the length, width, or ground clearance limitations.
Attach the weight to the car by drilling holes or routing grooves into the bottom, rear, sides, or top of the body, and filling the holes with the weights. The most desired place to attach weight is the bottom of the car. The holes are not visible when the car is upright, and imperfections can be easily hidden when they are on the bottom of the body. Loading the holes with wood glue, school glue, epoxy, or hot glue will keep the weights from falling out or moving around. It will also replace weight lost from drilling the holes. For more detailed information on weight and weight placement, see our WEIGHT page.
After the glue dries, the car body can be sanded. Start sanding with a coarse grade of sandpaper, then move on to finer grades until the car is as smooth as you want it.
Sand paper comes in different grades and types. A good thing to buy is a multi-grade package of assorted sandpapers for wood sanding. This package usually comes with sheets of 150 (coarse grit), 250 (medium grit), 400 (fine grit), and 800 or 1000 (super-fine grit).
Start with the 150-grit paper. Sand against the "grain" of the wood for shaping and removing excess glue or saw damage. A file or wood rasp will also be useful in shaping the body. To smooth the body, sand with the "grain". The more you sand with coarse grit sandpaper, the more wood you remove, and the smaller your car gets. Sand lightly and take your time.
Once the body has taken the shape you want, you should move up to the 250-grit paper. Sand only with the grain from now on. Sand using long, light strokes just to make it smoother. Remember, you are trying to make it smooth, not smaller. The more you sand with coarse grit sandpaper, the more wood you remove, and the smaller your car gets.
Now move on to 400-grit paper. Sand the body in the same manner as you did with the 250-grit paper. If you are going to paint your car, you can stop sanding once you have finished with the 400-grit paper. If you are going to stain your car to enhance the natural wood, you will want to skip down to these instructions.
Painting wood requires time and patience. The wood must first be "primed" with a wood primer BEFORE applying your color. Use a good wood primer, not an automotive primer made for use on metal surfaces. The primer coat provides a base for your color to bond to. Apply it in thin coats and allow it to dry between coats according to the manufacturer's directions. Apply at least two or three coats of primer. Allow the final coat to dry at least 24 hours. Sand the primered body lightly with 400-grit paper before application of paint.
The method for applying the color to the car depends on what type of paint you are using. Always follow the manufacturer's directions regarding drying times and ventilation requirements. When in doubt, allow 24 hours drying time, and paint in a well ventilated area. Enamel paints yield the smooth and shiny surface, but require long drying times. Water-based latex or similar paints yield a dull or "flat" color, but will dry quickly between coats. Whichever paint you use, be sure to apply it in multiple, thin coats, allow it to dry thoroughly between coats, and lightly sand the finish with 800 or 1000 grit paper before applying the next coat. This will allow for a better bonding surface when the next coat of paint is applied.
If you are really going for a "new car shine", you can always apply a thin coat of automotive wax to the body. If you wish to wax your car, please allow the final coat of paint to "cure" for at least three days in a well-ventilated area BEFORE you apply the wax.
Prepping your car for stain requires a little more work, but can yield a beautiful finish. After using the 400-grit paper, you will want to wet-sand the body. There are many methods to do this, but I prefer dunking the whole body into a pan or bucket of clean water. Don't drown the car, just hold it under and swirl it around for a few seconds. This will allow the wood grains to absorb water and swell. The surface of the wood will feel like "goose-bumps" when it is done correctly. Immediately sand the body while it is wet to remove these "goose-bumps". As you sand the wood, it dries out, the raised bumps are removed, and the car will be noticeably smoother.
Repeat the process again using the 800 or 1000 super-fine grit paper. After wet sanding, allow the car to dry thoroughly at room temperature for at least 24 hours before applying any stains or sealant.
When applying any stains or sealant, always follow the manufacturer's directions, wear latex gloves, and apply only in a well-ventilated area. Apply the stain in thin coats. Allow the stain to penetrate for a moment, and then wipe away the excess. If you apply too much stain in one place, or allow it to penetrate too long, the stain will appear uneven in color. Patience is the key when using wood stains. Always practice applying stain to a scrap piece of wood before staining the actual piece.
After the final coat of stain has been applied, allow it to dry for at least 24 hours. You can lightly sand the body using a fine grade of steel wool (#00) only. Now you can apply the sealant in a "flat", "satin", or "gloss" finish to achieve the desired effect. Apply at least one or two thin coats and allow them to dry 8 - 24 hours between coats. You can also use the steel wool between coats to aid the bonding of the next coat. Allow the final coat to dry 24 to 48 hours before handling it.
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