Cub Scout Pinewood Derby Official Rules

Wm Henry Harrison District Pinewood Derby

ALL CARS MUST PASS INSPECTION TO QUALIFY FOR THE RACE

Following are the inspection points and rules for the Pinewood Derby Race:

1. The car weight shall not exceed 5.0 ounces. The official race scale shall be considered final.

2. The overall length of the car shall not exceed 7 inches.

3. The overall width of the car shall not exceed 2 ¾ inches.

4. The car must have 1 ¾” clearance between the wheels.

5. The car must have 3/8” clearance underneath the body.

6. The wood provided in the kit must be used. The block may be shaped any way that is desired.

7. The wheels supplied with the kit must be used. The wheels may not be cut, drilled, beveled or rounded. You may remove the seam from the wheels.

8. The axles supplied with the kit must be used. They may be polished or lubricated.

9. Wheel bearings, washers or bushings are prohibited.

10. The car must not ride on any type of springs.

11. The car must be freewheeling, with no starting devices.

12. No loose material of any kind, such as lead shot, may be used.

13. If a car leaves its lane, at his sole discretion, the track chairman may inspect the track and, if a track fault is found which probably caused the initial violation, the track chairman may order the race to be rerun after the track is repaired.

14. If during a race, a car leaves its lane and, in so doing, interferes with another racer, then the car at fault shall be declared to have lost the race heat.

15. If during a race, no car reaches the finish line on the track, the car which went the farthest in its lane shall be declared as the heat winner.

16. Only dry lubricants such as graphite will be allowed for lubricating the wheels. Lubricants may not foul the track.

17. Only one lubrication is allowed before the beginning of the first race and then once again before the beginning of the first race of the semi-finals and finals.

18. Each heat will be announced.  Drivers will report to the starting line and place their cars on the track.  All other persons must remain behind the barrier.

19. The starter will make sure the cars are on the track properly.

20. The cars will be timed to the finish line.  The recorded time will be used to establish the first, second and third place winners.

21. When the results of each heat are recorded, the drivers will take their car to the official’s table.

Each car must pass inspection by the official inspection committee before it will be allowed to compete. The Inspection Committee has the responsibility to disqualify those cars that do not meet these specifications.

Happy Racing!

Pinewood Derby 10 Step Guide

Parents, following are 10 steps that should get your Scout well on his way to making an award-winning car.  For even more ideas, there are hundreds of sites on the Internet dedicated to Pinewood Derby cars.  Go to www.google.com, search for "Pinewood Derby" and you're on your way.  Just remember to make sure that your Scout's car adheres to the official pack rules.

Note:  The below times are approximate.  Your Scout should have plenty of time to complete the car with a little parental guidance.  Please utilize the workshops.

Step 1:  Design the car

On a piece of paper, sketch the side and top views of your car.  Include the locations in which you will place your additional weights, (and if you are changing the axle locations, where the new locations will be on the car).  Copy this design onto the wood block.

• Using graph paper to sketch the side view works well.

• Try and maintain the pre-drilled axle grooves in your design.  (If you are comfortable changing the wheelbase you may do so.  A longer wheelbase makes a faster, smoother riding car.)

Step 2:  Drill out the pre-cut grooves

Drill out the pre-cut axle grooves (or the new axle locations if you are changing them).  The diameter of the axles is 0.088", for which a #44 drill bit (0.086") is the best fit.

• If you don't have a #44 drill bit, a 3/32" (0.09375") bit will work.

• It is best to drill out the axle holes before you cut out the car body.  It is easier to drill a true hole in a squared block of wood than into a shaped piece.

• If available, a drill press will yield the truest axle holes.

Step 3:  Cut out the car body

Note:  All tools - especially power tools - should only be used under the supervision of an adult.  If you don't have access to a band saw, you will need to use a jigsaw, coping saw and possibly a chisel and hammer to remove the larger pieces of wood.

• It's a good idea to cut, chisel, or drill out areas for your weights at this time.

• We will have a band saw and other tools available at the Workshops.

Step 4:  Shape and sand the car body

The wood is very forgiving, so a little time and effort with medium grit sandpaper and a final sanding with fine grit sandpaper will produce great results.

• A small wood rasp can also be useful.

• Shaping, smoothing, and detailing can also be done using a Dremel (or similar) tool.  Again it bears repeating: All tools - especially power tools - should only be used under adult supervision!

Step 5:  Preliminary length and weight check

Measure the length of your car and make adjustments if necessary.  Weigh the body, axles, weights, wheels and anything else you plan to attach to the car, all together on your scale. Without paint and glue/epoxy (to secure the weights, axles, etc.,) the total weight should come to around 4.7 ounces. 

• Depending on the amount of paint and glue/epoxy you use, your preliminary target weight might be more or less.  (Weights and any other fixtures on the vehicle should be firmly secured.  A 5-minute epoxy is good for this.)

• If you don't have access to a scale, utilize the workshops to help get to your desired weight.  Note:  The scale provided by Pack 614 gives the official weight of record.  If your car ends up weighing over 5 ounces on the official scale, the weight must be brought down to or below the 5 ounce limit before it can be accepted at the Final Weigh-In.

Step 6:  Paint and detail the car body

A few coats of high gloss spray paint work well.  The boys can hand paint for greater detail if desired.

• Remember that several thin coats of paint make for a better finish than one thick coat.  Let the paint dry thoroughly after each coat.  Lightly sand the entire car with fine sandpaper between coats.  Do not sand after the final coat.

• Add decals and/or stickers after the final coat of paint has thoroughly dried.  Be sure to place the assigned car number on top rear of the car.  (This helps us during the Derby to quickly identify the car owner and what is the front/rear end of the car.)

• If weight is being inserted into the chassis, you may wish to do this prior to painting.

Step 7:  Prepare the wheels and axles

Sand away the mold projections on the wheels and axles.

• Remove the burrs from the underside of the axle heads with a small file.  This is most easily accomplished by placing each axle in a drill.  With an adult holding the drill on, use the file to remove the burrs under the head.

• Smooth the axles with fine sandpaper.  A lightly moistened, fine grade wet-dry sandpaper works best.

• Polish the axles to a mirror finish using toothpaste, wet pumice, or jeweler's rouge on a strip of cloth.

• Lubricate the wheel/axle assembly by spinning powdered graphite into it (using the drill, or by hand).  Note:  Do not use liquid lubricants since they may damage the plastic wheels.

Step 8:  Install the wheels and axles

Place a small amount of wood glue or glue from a hot glue gun into the axle groove prior to installing each wheel/axle assembly.

• Line the axle/wheel assembly up straight, and then carefully push it into place.  (Very light hammering may be necessary to set the axles in the car.)

• Try and get the wheel hubs within 1/32" of the car body.  This will allow for a smoother faster ride.

• With the wheels properly installed, the car should be able to run smooth and straight for a reasonable distance.

Step 9:  Lubricate the wheels and axles

Friction is the enemy!!  Prior to the final weigh in, work lots of graphite into the wheels and axles.

• Be sure to add the graphite in an appropriate area in your house.  (Mom might harm the author if graphite ends up all over her furniture or carpet.)

• When done adding the graphite, wipe the excess off the car body, and don't be a slob - wash your hands.

Step 10:  Final weight check

Make sure your car's weight is as close to 5.0 ounces without going over.  Make final adjustments as necessary prior to turning the car in at the Final Weigh-In.

• The volunteers will not be modifying cars at the Final Weigh-In.  The workshops were created with that purpose in mind.

Miscellaneous Construction Tips

      Avoid narrow, pointed noses when designing your car.  They are legal, but are sometimes difficult to stage at the starting line.  More importantly, the cars are detected as they cross the finish line because the front end of the car blocks a light beam, and this type of design may not trip the sensor correctly.

      "What's your clearance, Clarence?"  It is very tempting to simply screw those flat weights to the bottom of the car.  However, if you do, your car will likely not clear the center guide strip on the track.  You must inlay the weights if you are 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 straight ("true") holes into a squared block of wood than into a shaped piece of wood.

      Do not epoxy the axles into 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 a hot glue gun instead.

      Check your car's length early on in the process.  This was also stated earlier, but it also bears repeating.  Better to trim it sooner than later!  (The uncut block of wood in the Grand Prix Pinewood Derby Kit is 7" long.  If you don't cut the length shorter and  happen to add fins, lights etc., you're going to have a problem.)

      Have your car as close to complete by the Final Weigh-In date.  Then, at Final Weigh-In all you have to do is weigh it and make any last minute adjustments before turning it in.