1. What is the diameter of a Pinewood Derby axle? Pinewood derby axles are one inch long, 0.087 inch diameter zinc plated steel nails. The minimal axle treatment is the removal of the burrs and crimp marks with a file, followed by sanding and polishing.
2. We offer several options for your pinewood derby block or kit. First, select a block or kit, then select one or more applicable standard options. If the number of kits/blocks does not equal the number of options, please include a comment during the checkout process.

Pinewood derby axle slot dimensions. Your gaming session for Grosvenor Poker will only include the time spent within Grosvenor Poker and will not take into account any time you have spent playing any of our other games on our website.

• Preface
• Rules
• Block
• Wheels
• Axles
• Assembly
• Physics
• Appendices

This chapter covers designing the car, setting the wheelbase and drilling the axle holes, cutting out the block, adding weight holes, sanding, and painting. At the end of this process, you will have a car body that weighs approximately 4.25 ounces that is painted and is ready for the insertion of wheels and axles. If you are not absolutely sure about what is allowed in your pack, district, or other organization's rules, now is the time to find out. Remember, there is no single set of rules and there is wide variation among the different sets. Get a hard copy of your organization's latest rules and if you have any questions, ask. Of particular importance in this chapter is whether the stock wheelbase and axle slots must be used. Another issue is the weight of the wheels. If your organization allows light wheels, you will need up to one-third of an ounce of additional weight in the body to make up for the reduced wheel weight.

Designing the car[edit]

The standard pinewood derby block is approximately 7.0 inches long by 1.75 inches wide by 1.25 inches tall. It has a typical density of 0.0138 lbs/in³.^[1] The block is supplied unsanded with grooves cut on the bottom side to accept the axles. The blocks weigh approximately 3.4 ounces.

The first step in designing your car is picking the wheelbase. If the rules of your race do not specify that the original wheelbase or axle slots must be used, it is often possible to improve car performance using the longest wheelbase. WIth a long wheelbase, the weight can be moved further to the back while still remaining forward of the rear axle and errors in wheel alignment will affect the long wheelbase car less since it has a larger turning radius for a given angular wheel deflection. The standard pinewood derby wheelbase is about 4.5 inches. The extended wheelbase is 5.75 inches with the wheels 5/8 inch from the end of the 7 inch block.^[2] Even when the standard wheelbase is required by the rules, it may be possible to move the rear axle back by cutting off the back of the block, leaving 5/8 inch between the axle slot and the back of the block, and gluing the removed piece to the front of the car.

A design template may be useful for designing your car. There are templates available online (both free^[3][4] and commercial^[5][6][7]) Keep in mind where the weights will go and how much space you will need. Remember that you want the center of gravity to the rear and low.

Drilling the Axle Slots[edit]

Axles can be installed in slots or holes. Unless installation in the original slot is required, a drilled axle hole will make wheel and axle alignment easier. If the axle slots must be used, you should still drill a pilot hole in the slot to assure that it is the correct size. The holes should be drilled with a #44 bit (0.086 inch decimal equivalent) for a 0.087 inch axle. A #43 (0.089 inch decimal equivalent) can be used for oversize axles or pre-1999 car kits.^[8] The bit should be held in a drill press or, if one is not available, an axle hole jig can be used.

The performance of the car can often be improved if one wheel (typically front) is raised approximately 1/32 to 1/16 inch on the car body. This wheel is not in contact with the track and doesn't spin, thus (ideally) the rotational energy is lower and translational kinetic energy (and speed) is higher (see the chapter on Physics for more information). Note that the wheel-to-axle friction is not reduced since the car's weight is distributed on three rather than four axles. The raised wheel may still contact the guide rail and, if it contacts the track, energy is expended when the wheel spins up to speed. The smoother the track, the greater the three-wheel advantage.

Cutting out the block[edit]

After you have settled on a design, drilled the axle holes and decided where the weights will go, it is time to cut out the block. Use a pencil to mark the cuts and use a coping saw, scroll saw or band saw to cut the block. The venerable wedge or 'flying doorstop' design can be created with a single cut of a miter saw. After cutting, a wood file or rasp or a hand held rotary tool, such as the Dremel Moto-tool can be used to round edges and add detail. A small amount of wood whittling can be used to good effect.

Once the overall shape of the block has been achieved, use sand paper to create a smooth surface. Start with coarse (50 to 60 grit), and move on to finer grit (150 to 220).

It is often easier to cut the weight holes (see below) before cutting out the body.

Adding weight[edit]

Before painting the block, you will want to add enough weight to bring the block, wheels, axles, and any accessories to about 4.9 ounces. Do not go over this weight; it is easier to add weight than to take it away, especially if you plan ahead.

The best car designs typically have the center of gravity (balance point) such that most of the weight is over the rear wheels. A center of mass 1 to 1.25 inches in front of the rear axle is readily achieved and gives good performance.^[9] A rear bias places more of the downward force on the rear wheels and less on the front wheels (one of which may be raised anyway^[10]) Another positive effect of rear weight bias is the slightly greater potential energy that results from the car center of mass starting at a greater height above the flat portion of the track. However, if the weight is too far to the rear, the nose of the car may lift and the car may jump the track. This is a greater problem on older wood tracks. On S-shaped tracks with a gently sloping start, a front bias can be helpful for quick acceleration.^[11]

Several materials and a number of different kinds of weights can be used and each requires planning for proper placement.

Lead

Lead is the one of the most often used weighting materials for pinewood derby cars. Lead can be easily cut to achieve the desired weight. Drawbacks are its toxicity, especially the fumes when heated. Melting and pouring lead is not recommended due to dust and fume inhalation and the possibility of splashing onto the eyes and skin.^[12] A 3/8' diameter lead wire weighs one ounce for every 1-1/2'.

Tungsten

Tungsten is about 70% more dense than lead (19.25 g/cm³compared to 11.34 g/cm³) and therefore gives you the same weight in about 40% less volume. Another benefit is that, unlike lead, tungsten is not toxic. On the other hand, tungsten is hard and difficult to machine, so addition and subtraction of weight must be done by adding and subtracting tungsten ball bearings or powder. Two half-ounce 3/8' diameter tungsten cylinders is just over 3/4' end-to-end.

Zinc

Zinc is less dense than either lead or tungsten (7.14 g/cm³), but it is not toxic and can be cast into parts that can be attached to the car with screws or nails.^[13]

The standard wheel and axle set weight about 0.48 ounces, therefore a good target weight for the block prior to wheel and axle insertion is 4.42 ounces. Put the block, wheels,and axles on the scale and add weights until the total is about 4.9 ounces. This leaves a tenth of an ounce to add prior to weigh-in; remember that it is almost always easier to add weight than to subtract it. At this point, make sure that you have a plan for bringing the car up to weight after painting and installing the wheels and that you can easily adjust the weight during the weigh-in process. Adhesive weights can be used, but it is critical that the correct guide rail clearance is maintained under the car. If you do not want to add weight to the top of the car, you should have a recessed area for weights underneath.

Weight holes can be cut using a brad point drill bit either from the rear or across the car body. Use a drill press or use care with a hand drill. The brad point drill bit (also called the lip and spur or dowelling bit) is a variation of the twist drill which is optimized for drilling in wood. Conventional twist drill bits do tend to wander when presented to a flat workpiece.

Center the weights in the body and glue them in place. Add body filler or wood putty and sand smooth. The center of mass of the body can be determined by placing the body on top of a drill bit and moving it back and forth in seesaw fashion until the balance point is reached.

Painting[edit]

Pinewood Derby Axles For Sale

Once the block is at the proper weight with axle holes or axle slot pilot holes drilled, it can be painted. Use a good wood primer and sand between coats with 400 and 600 grit wet or dry sandpaper that has been dipped in water. When the primer has been applied, a spray paint for plastic model or general applications can be used.

Windows can be added using silver enamel with black frames, headlights in yellow and tail lights in red. Decals or stickers can be used for additional decoration.

Be creative, have fun, but give the block a few days to a week to dry before assembly.

Waxing your paint will make for less wheel braking friction also before assembly. A small amount of graphite spray paint can be applied to the point where the hub contacts the car body.

References[edit]

1. ↑BSA Standard Block - Dimensions and Mass Properties
2. ↑Precision Drilled Block
3. ↑Free Pinewood Derby Plans
4. ↑Car Outline Cutting Guides
5. ↑Pinewood Derby Car Design Help
6. ↑Winning Pine Derby Car Plans
7. ↑Pinewood Derby Car Designs
8. ↑New pinewood derby kits in 1999/2000
9. ↑Ol' Buffalo Pine Car Page
10. ↑Learn to Build A Winner by Stan Pope: How To Improve A Pinewood Derby Racing Car
11. ↑Learn to Build A Winner by Stan Pope: Science 101
12. ↑The Airborne Lead Hazard
13. ↑Pinewood Derby Car Weights

• Preface
• Rules
• Block
• Wheels
• Axles
• Assembly
• Physics
• Appendices

There is no single set of Pinewood Derby rules; each Pack, District or Council is free to set its own rules.^[1] However, car construction rules have appeared in some BSA publications. Many rules such as size, weight, bearings, bushings, and springs are common to nearly all Pinewood Derby rules. For example:

Dry Lubricant

Many rules sets specify dry lubricant only and some allow only graphite and Teflon explicitly. Other rules allow liquid lubricants as long as they are not wet at the time of the race.

Axle Modification

Some rules prohibit axle grooves and beveling. Most prohibit substitution of non-BSA axles (e.g. nickel-plated).

Wheel Modification

Some rules prohibit light wheels. This is typically worded as prohibiting removal of 'substantial mass' and requiring that the inner wheel wording be visible. Some rules prohibit wheel coning or modification beyond light sanding. More detailed rules prohibit narrow wheels or those with one (V-tread) or two (H-tread) raised tread areas.

Wheel Mounting

There are three levels of wheel mounting rules: 1) no restriction, 2) original wheelbase dimension, 3) original wheelbase and axle slot (no new holes). In some cases, the raised wheel modification may be prohibited.

Aftermarket Parts

Most rules (e.g., the BSA rules above) do not preclude the use of aftermarket parts as long as they are derived from the BSA kit. For example, lathed wheels or grooved axles are acceptable if the parts originate from BSA kits. Some rules expressly prohibit this type of substitution, although enforcement can be problematic.

Ready Made Cars

It is generally regarded that ready to run cars violate the spirit of the Pinewood Derby even if they do not violate a specific rule specifying that the car be built substantially by the Cubscout. However, ready to race cars created from BSA kits can be found on eBay and other sites.^[2][3][4]

Rules in the box[edit]

The rules that come in the Grand Prix Pinewood Derby Kit (BSA Kit 17006) are known as the 'Rules in the Box.'^[5]

1. Car Specifications: Width: - 2-3/4'; Length - 7'; Weight - Not over 5 Ounces; Width between wheels - 1-3/4'
2. The car must have been made during the current year (year in which derby is being held) - Cannot use previous years cars - Pinewood Derby Car kits supplied by the pack
3. Wheel bearings, washers, and bushings are prohibited.
4. The car shall not ride on springs.
5. Only official Cub Scout Grand Prix Pinewood Derby wheels and axles are permitted.
6. Only dry lubricant is permitted.
7. Details, such as steering wheel and driver are permissible as long as these details do not exceed the maximum length, width and weight specifications.
8. The car must be free-wheeling, with no starting devices.
9. Each car must pass inspection by the official inspection committee before it may compete.
10. If, at registration., a car does not pass inspection, the owner will be informed of the reason for failure, and will be given time within the official weigh-in time period to make the adjustment.
11. After final approval, cars will not be re-inspected unless the car is damaged in handling or in a race.

Cub Scout Leader How-To Book[edit]

Car construction rules from the 'Cub Scout Leader How-To Book' (BSA No. 33832).

Cub Scout Grand Prix Pinewood Derby Guidebook[edit]

Example Pinewood Derby car construction rules from the 'Cub Scout Grand Prix Pinewood Derby Guidebook' (BSA No. 33721).

1. The car must have been made during the current year (the year in which the derby is held).
2. The width of the car shall not exceed 2-1/4 inches.
3. The length of the car shall not exceed 7 inches.
4. The weight of the car shall not exceed 5 ounces.
5. Axles, wheels, and body wood shall be as provided in the kit.
6. Wheel bearings, washers, and bushings are prohibited.
7. The car shall not ride on any kind or type of springs.
8. Any details added must be within length, width, and weight limits.
9. The car must be freewheeling, with no starting devices.
10. No loose materials of any kind (such as lead shot) are allowed in the car.
11. The official number must be clearly marked or visible on both sides of the car.

Wotamalo Rules[edit]

Wotamalo District rules section on car construction^[6].

1. Material:Race cars shall be constructed for this event from the parts contained in the Official Grand Prix Pinewood Derby Kit (referred to below as the kit) as sold by the Scout Service Center, [for the District in which the race is run]. Materials from the kit may be supplemented but not replaced.
2. Weight: Race cars may weigh no more than five (5) ounces (total weight) as determined on the official scales during race day inspection.
3. Wheels and Axles: The car shall roll on the wheels from the kit. The wheels shall turn about the axle nails from the kit. The axle nails shall be firmly affixed to the wood of the car body. The axle dimensions may not be changed substantially. The outside surface of the axle head (the non-contact surface) may not be changed substantially, such as, by polishing. It must be obvious to the judges that the wheels and the nails from the kit are being used.
4. Size: Race cars may be no longer than 7 inches, nor wider than 2 3/4 (2.75) inches, nor taller than 3 inches, as determined by the official gages during race day inspection. (Underside clearance of at least 3/8 (0.375) inches and inside wheel to wheel clearance of at least 1 3/4 (1.75) inches is recommended, so that the car will run on the racetrack. Adequate clearance is the responsibility of the race car builder.)
5. Weights and Attachment: Weight may be added to the car and will be considered part of the car for purposes of all measurements. 'Weight' is considered to be any material on the car that is not provided in the kit. All weight must be securely fastened to the car, e.g., by permanent glue, nails or screws, but not by 'sticky substances', e.g., tape, or tack spray. Weights shall be passive, i.e. non-movable, non-magnetic, non-electric, non-sticky, etc.
6. Wheels: Wheel treatment (hub and tread smoothing and polishing) may not result in substantial removal of mass nor in reducing the tread (track contact) width from the original kit wheels. Wheel tread surface must be cylindrical. The words 'Official B.S.A. Made in U.S.A.' and other lettering on the wheels shall remain intact and clearly visible to the inspector. Some of the original 'tread marks' on the wheel face must be intact, i.e. apparent to the inspector.
7. Unacceptable Construction: The following may NOT be used in conjunction with the wheels or axles: hubcaps, washers, inserts, sleeves, bearings.
8. Gravity Powered: The race car may not be constructed or treated in such a way that the track's starting mechanism imparts momentum to the car. (For instance, this provision disqualifies cars with sticky substances on the front of the car and protrusions which may catch on the starting pin.)
9. Lubricants: Lubricants must be dry at the time of inspection and racing.
10. Staging: The entire car must stage behind the starting pin.
11. Body: The car body may have no moving parts.

Pack 254 Rules[edit]

From the Virtual Cub Scout Leader's Handbook, these are a stricter version of the Watamalo Rules.

1. Material: Race cars shall be constructed for this event from the parts contained in the Official Grand Prix Pinewood Derby Kit (referred to below as the kit) as sold by the Scout Service Center, [for the District in which the race is run]. Materials from the kit may be supplemented but not replaced.
2. Weight: Race cars may weigh no more than five (5) ounces (total weight) as determined on the official scales during the pre-race check-in. Note: The official scale will be available in the Palmer School office from January 4th until registration.
3. Wheels and Axles: The car shall roll on the wheels from the kit. The wheels shall turn about the axle nails from the kit. The axle nails shall be firmly affixed to the wood of the car body, and MUST be placed in the original 'axle grooves' in the supplied wooden block. It must be obvious to the judges that the grooves, wheels, and the nails from the kit are being used.
4. Size: Race cars may be no longer than 7 inches, nor wider than 2-3/4 (2.75) inches, as determined by the official gages during the Registration and Inspection. Underside clearance of at least 3/8 (0.375) inches and inside wheel to wheel clearance of at least 1-3/4 (1.75) inches is recommended, so that the car will run on the race track. Adequate clearance is the responsibility of the race car builder.
5. Weights and Attachment: Weight may be added to the car and will be considered part of the car for purposes of all measurements. 'Weight' is considered to be any material on the car that is not provided in the kit. All weight must be securely fastened to the car, e.g. by permanent glue, nails or screws, but not by 'sticky substances', e.g. tape, or tack spray. Weights shall be passive, i.e. non-movable, non-magnetic, non-electric, non-sticky, etc.
6. Wheel Treatment: Wheel treatment (hub and tread smoothing and polishing) may not result in substantial removal of mass nor in reducing the wheel width from the original kit wheels. Some of the original 'tread marks' on the wheel face must remain intact, i.e. apparent to the inspector. Wheels may not be machined to a beveled condition and the portion of the wheel surface that contacts the track must remain parallel to the axle.
7. Unacceptable Construction: The following may NOT be used in conjunction with the wheels or axles: hubcaps, washers, inserts, sleeves, bearings.
8. Gravity Powered: The race car may not be constructed or treated in such a way that the track's starting mechanism imparts momentum to the car. (For instance, this provision disqualifies cars with sticky substances on the front of the car and protrusions which may catch on the starting pin.)
9. Lubricants: Only dry lubricants such as graphite or powdered Teflon 'white lube' will be allowed for lubricating the wheels. Lubricants may not foul the track. There will be a lubrication table set up at the race. In the interest of fairness, only one lubrication is allowed before the beginning of the first heat race and then once again before the beginning of the first race of the semi-finals and finals.

Table of Rules[edit]

B = Rules in the box

H = How to book

P = Pinewood derby guidebook

W = Wotamalo Rules

2 = Pack 215 Rules

References[edit]

Pinewood Derby Axle Bender

1. ↑Pinewood Mania Rules and Race Procedures
2. ↑Super Fast Pine Wood Derby Car
3. ↑Completed Pinewood Derby Cars
4. ↑AG Derby Cars
5. ↑Grand Prix Pinewood Derby Kit Rules
6. ↑Wotamalo District Pinewood Derby Rules

Pinewood Derby Axle Slot Dimensions Free