The little brother to the soap box derby, the pinewood derby is a high-octane time that anyone, no matter how young or old, can enjoy. A traditional part of any Cub Scout Pack's year, pinewood derby has been widely acknowledged as an essential part of American childhood. Reader's Digest even called it one of the top 100 celebrated "rites of spring." While the kids (often with more than a little parental interference) will bring the cars, someone has to put together track.
Lay lengths of plywood end to end. Plywood should be 14 inches wide and total 32 feet in length. Your lengths are likely to be 8 feet each, necessitating four lengths of plywood.
Place pine lattice strip track pieces. These will be your lane guides. The pinewood derby cars rest on top of these, keeping the cars from going off center. For four lanes of track, you will need 128 feet of 1/4-inch thick and 1 3/8-inch-wide pine lattice strips. Space the center of each track 3 1/2 inches from the adjacent lane, leaving the center of the two edge lanes 1 3/4 inches from the sides of the plywood.
After ensuring that each 8-foot length of pine lattice strip is flush, drill down the track strips. Make sure to pre-drill each hole to ensure that the tracks do not crack. Use 1/2-inch wood screws to affix each lattice strip to the plywood.
Pre-drill holes in the 1-inch-thick board segments. Cut board segments to six inches each, then pre-drill holes through the pine lattice strips two inches outside of each joint. Use a wider bit to countersink the holes to accommodate the bolt heads, allowing them to sink beneath the level of the pine lattice strips. With three lengths of plywood track (the fourth length will attach in a different fashion) and two six-inch connector pieces to each joint, you will need a total of four lengths of six-inch board.
Insert bolts through the top of the track and screw wing nuts into place on the other side. Bolts should sink beneath the level of the lattice strips, preventing them from interfering with cars rumbling overhead. The use of wing nuts will allow the easy removal of the 1-inch-thick board pieces for disassembling and storing the track.
Affix the final track segment to the other three using 1/2-inch wood screws and door hinges. This way, the first track segment can be raised at an angle from the other three, allowing for an elevated starting position.
Using a protractor and a yardstick, angle the beginning track segment up by 30 degrees, then measure down to the ground. 30 degrees is considered the optimum starting position for a good race.
Build two back legs using 2x4s. Cut two 2x4s to a length 5 inches higher than the peak of your angled track segment. Nail another 2x4 between the two lengths at the proper height. Cant this shelf board at a 30-degree angle.
Build two legs at a lower height to add support. These legs could be anywhere between one and two feet from the hinge. Simply build a version of the 2x4 shelf built in the previous step, except to the height of the particular segment it will be supporting.
Add a cross support between the two leg segments. A single 2x4 nailed perpendicular to a front and back leg will provide lateral support for the standing section.
Build the starting gate. Cut a notch into the top of the extra five inches of 2x4s above the back legs on each side of the track using a Dremel tool, then insert the wooden dowel going across the top of the track. Using wood glue, affix three-inch flaps of pine lattice to hang down over each lane. When the cars are ready to go, turn the wooden dowel to lift the front of the pine lattice flaps and set the cars off equally.
Install the finish line. Two feet from the end of the flat segment of track, paint a red line across the length of the track. This will be your finish line. Above this red line install a digital stop clock, which will light up the lane winner for each heat. Specialized pinewood derby finish line detectors can be found by following several links provided below.
Place pillows at the end of the track. The fastest cars may come in with quite a bit of speed, so give them a soft space for a crash landing.