Cub Scouts Pack 83 of Belmont, CA
Pinewood Derby Builder's 20-Step Checklist
Use a number 2 pencil to draw your
design on the paper from the front, top and side views.
Use a number 2 pencil to heavily trace over your
design on the back of the paper and deposit lots of pencil lead on the lines, then tape the paper onto your block and retrace the design from the front of the paper...this will transfer the lead lines to your wood.
Use a number 2 pencil to redraw your
design directly onto the block from your transfer so you can see exactly where to cut. Be sure to do the side, top and end views.
Use a small square and a coping saw to make sure that the slots in the bottom of the block are exactly 90 degrees to the side of the block. This will make the wheels track straight and not steer into the track bumpers, slowing down your car.
Be sure that you hold the saw perpendicular to the block of wood so you get a straight 90-degree cut from the side to the cut surface.
80 grit is very coarse. You can use an electric orbital palm sander to speed the process. Round the corners and shape the car the way you want it to be.
120 grit is medium courseness and makes a smoother surface but does not remove material as fast as 80 grit.
240 grit is even finer and produces a smoother surface than 120 but does not remove material as quickly.
Sanding sealer is also sometimes called "shellac". Sanding sealer soaks into the surface of the wood and plasticizes the surface so it can me sanded more smoothly than bare wood and also prevents the final paint from soaking into the wood and producing a dull finish.
400 grit is super smooth and removes material very slowly. This step should result in an amazingly smooth surface.
Some surfaces may have been sanded bare in the previous step, so this step makes sure the entire surface is sealed.
This will produce the final smooth surface ready for the final paint job.
A clean chamois cloth slightly dampened will help remove all the dust from the surface of the car.
Use gloss model spray paint for model cars. Regular spray paint is not recommended because it dries slower than model paint and regular paint is not as "fine" as model paints. Give the car many light coats and let it dry between each coat...avoid the temptation to give it one heavy coat because this will surely cause runs and will take a long time to dry and may even remain soft up to race day and beyond, and finger prints will easily be pushed into the soft paint. You may want to rig up a small fan and air filter to prevent dust from settling on your paint job as it dries. If dust does settle, you can wait until the paint os completely hardened (about 12 hours indoors) and wet sand it with 600 grit wet and dry sandpaper under running water to remove the dust specks. Then dry the car completely and apply another finish coat.
If you want more speed, be sure to clean the flashing off the nails and wheels before assembling. You can also polish the axles to a mirror finish with fine sandpaper or polishing compound. Check the wheels for molding imperfections and remove them with fine sandpaper. Turn the car upside down into a soft cloth. Put the nail axles through each wheel, then press the side of each nail down into the axle slot in a dry fit. Make sure you press the nail all the way down into the slot. Then pull the nail back out and apply graphite or other dry lubricant in the wheel bore and to the axle, and put the axle through the wheel. Place a small amount of mixed up 5-minute epoxy into the slot and press the axles back in, leaving a 0.037" gap between the body block and the wheel hub. Be sure to keep the epoxy away from the wheel. Set the car on its wheels on a sheet of glass or other very flat surface, and allow the epoxy to set for 30 minutes without touching.
You can use any accessories and stickers as long as you do not exceed the maximum dimensions or weight (you do not have to use BSA or "official" accessories).
Depending on your car's design, you can drill a hole into the underside of your car or in some other surface and add lead-free or lead weights to bring the car to just under 5 ounces. You can also apply weights directly to the surface. Be prepared to be able to remove or add weight on race day without wrecking your car.
You can use any good automotive polish like McGwuire's or Turtle Wax and polish the car to a high shine.
These dry lubricants are available at hobby shops and dramatically reduce the friction on the surfaces where the wheel and axle meet. Reducing this friction is probably the most significant way to speed up your car.
Bring extra weights and dry lubricant with you to race day, along with your registration fee, and good luck!