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The science behind building a fast pine car is pretty simple. You want to start with as much potential energy as allowed and convert as much of it to kinetic energy as possible.
Potential energy is height times weight, so the higher and heavier your car is, the more potential energy it has. Since the cars are placed on the track at an angle, the rear of the car is its highest point, so you want to put most of the weight in the back of the car. And you want it to weigh as close to 5.0 ounces as possible without going over.
Not all of that potential energy will be converted to kinetic energy. Some of it will be converted to heat through friction. The car that wins the race will be the one with the most potential energy that loses the least amount to friction. You need to eliminate as much friction as you can.
If You Want to Build a Car...
Following the steps in the next section, you could spend close to $300 trying to win a $7 trophy. It's a blast, but if you just want to build a car to enter for fun, here's what you do:
Cut a Wedge
Make a mark 1/4" up on the front end of your block (where the axle slot is further from the edge), and mark 1/2" up on the back end. Duplicate the marks on both sides and connect them on the ends.
Use a coping saw to cut out the shape.
Couple Coats of Paint+Primer
Sand it down as much as possible, put toothpicks in the axle slots, and spray it with a few coats of Rust-Oleum Painter's Touch 2X Gloss paint.
Cheap Speed
If you have a PineCar retailer nearby, or enough time to place an online order, this $14 Speed Kit will add the most speed for the least amount of money. You'll just need a power drill for sanding your wheels and axles. Don't install the weight until you get to the race. Don't forget your screwdriver to attach it.
Apply Graphite
Apply graphite to the hub, bore, and tread of all four wheels and to the shaft and back of the head of all four axles.
Wheel Insertion
If you're shopping at a local PineCar retailer, this $17 Axle Placement Guide will make it a lot easier dealing with those axle slots. If you have time to place an online order, you can get a similar tool for $9 from PinewoodPro.com.
Insert the tool in the axle slot and slowly and gently insert each wheel. Once I get the axle partially inserted, I use the back end of a screwdriver to press the wheel in until it touches the tool, which provides the correct amount of spacing.
Add Weight
Weigh the body, weight, and weight screws together, incrementally removing sections of the weight with needle-nosed pliers until you get to 5.0 ounces, then attach the weight.
If You Want to Build a Competitor...
Phillips Head Screwdriver
Power Drill
Measuring Tape
Super Glue
Speed Square - $6
Trigger Clamp - $13
220 Grit Sanding Sponge - $10
Sandpaper:
1000 grit - $9
2000 grit - $9
3000 grit wet or dry (optional) - $9
Coping Saw ($14) or access to a Bandsaw, Scrollsaw, or 12" Mitre Saw
If you have access to a drill press:
1" Forstner Bit - $13
If you do not have access to a drill press:
3/8" Drill Bit
Masking Tape
Weight Guide - $19
Derby Guys Paint System (optional) - $20
Sanding Sealer (optional) - $27
Primer - $7
Paint - $7
Clearcoat - $7
Digital Scale - $12
Axle Polishing System - $10
Axle Finishing Kit (optional) - $12
Axle Hole Drilling Tool - $20
BSA or PineCar Precision Stock wheels - $10-50
Graphite - $12
Know Your Rules
I'm not here to tell you how to cheat, but I will help you find opportunities that others may not see. Have a question? Click Contact at the top of the page and send me your rules.
Know what your rules will allow, especially pertaining to wheels and axles.
If you don't have to use the precut axle slots, drill axles holes.
If you don't have to have the front and rear axles a specified distance apart, extend your wheelbase.
If your axles don't have to be straight, cant your wheels.
If you don't have to have four wheels touching the track at the same time, raise a front wheel.
If you can do any of those four things, read the next section and do what the rules allow.
Custom Axle Holes
It's difficult to insert axles into the precut slots on pine car blocks, they're prone to break, and they aren't placed in optimal positions. Don't use them unless your rules say you have to.
I prefer to just cut the axle slots off the car completely, so place the block with the axle slots on the bottom.
2. Measure 5/8" from each end and draw a line across it with a speed square. This is where your axle holes will go.
3. Measure 7/8" from the edge and mark the center of the block, lengthwise, with the speed square.
4. Mark 1 3/8" from one end of the block and draw a line there with the speed square.
5. If you have access to a drill press, use a 1" Forstner bit to drill a 1/2" deep hole where the blue and green lines intersect. You'll place your weight there later. If you don't have access to a drill press, skip this step.
Next, use the Pinewood Pro Axle Hole Driller Tool (AHDT), a trigger clamp, a Phillips head screwdriver, a power drill, and the bit that comes with the AHDT to drill axle holes where you marked the red lines.
Place the AHDT on the bottom of the car and align it with the lines you drew (the red lines in the diagrams above). You should see the line through the little hole I marked here:
Push down on the AHDT and use the trigger clamp to squeeze the sides of the Axle Hole Tool onto the block, then tighten the screw with the Phillips head screwdriver. Remove the clamp.
3. Notice that this image shows the current version of the AHDT, and that it is what the tool looks like when it's mounted to the body of the car, specifically that the raised wheel guide is the lowest hole, because the car is upside-down.
On the front of your car, if your rules allow, drill through the Raised Wheel Hole Guide on one side of the car and the Straight Axle Hole Guide on the other. If not, drill through the Straight Axle Hole Guide on both sides.
A raised wheel does not reduce friction - the friction is just distributed equally to three wheels instead of four - instead, you only have to expend energy starting three wheels instead of four, so you are conserving energy that can be converted to kinetic energy.
Even though the wheel doesn't touch the track, it serves a purpose. If the car starts to veer to the right, a raised left wheel will touch the track's guide rail and keep the car in its lane.
4. If your rules allow canted axles, place the Axle Tool on the body so that one of the outer holes aligns with the line you drew for the rear axles, and drill through the 2.5-degree Angled Holes on both sides. If your rules do not allow canted axles, drill through the Straight Axle Hole.
With canted axles, only the inside corner of the wheel touches the track, which results in a large reduction in friction.
Your block should look like this, but without the big weight hole if you don't have access to a drill press.
Get in Shape
The wedge shape isn't fancy, but it's easy to cut and paint, it's aerodynamic, and it helps keep the weight in the back of the car.
Mark 3/4" from the bottom of the back of the car and 3/8" from the bottom of the front of the car and draw a line.
The easiest way to make this cut is with a 12" mitre saw.
No Drill Press, No Problem
If you don't have access to a drill press, go to ABC Pinewood Derby, click Tools on the left, scroll down to the Weight Guide, type a 1 in the box, scroll down almost to the bottom of the page, and click Add Selected Items to Cart.
Use the trigger clamp to attach the guide to the back of your car.
Measure 1 1/4" from the tip of a 3/8" drill bit and wrap the bit with masking tape to mark the length. Drill into the guide holes until the masking tape reaches the guide.
Jump to the Weight section, then come back to Sand and Seal.
Sand and Seal
Get a 220 grit sanding sponge and have your racer sand every side except the bottom until he says, "Holy cow! I didn't know wood could feel this smooth!"
Get some 1000 grit sandpaper and have your racer sand every side except the bottom until he says, "Holy cow! I didn't know wood could feel this smooth!"
Get some 2000 grit sandpaper and have your racer sand every side except the bottom until he says, "Holy cow! I didn't know wood could feel this smooth or that my arm could be this tired!"
Insert some toothpicks in the axle holes, get some sanding sealer and a foam brush, and have your racer apply a smooth coat to the car.
After it dries, get another sheet of 2000 grit sandpaper and have your racer sand every side except the bottom until he says, "Holy cow! I didn't know wood could feel this smooth!"
Tip: I really like using this Derby Guys Paint Handle. It allows you to cover the entire body with each coat with no pooling.
Tip: If you cut a wedge, find a flat surface and duct tape sheets of 1000 and 2000 grit sandpaper down. Your racer can rub the body on the paper instead of rubbing the paper on the body, which makes it a lot easier.
Prime Time
Get a can of Rust-Oleum Painter's Touch 2X Primer. Use white if you want to use a light or medium color on your car; use black if you want to use a dark color.
Find a flat surface, turn a cardboard box upside down, and place two yellow hexagonal #2 pencils on it, then put your car on top of the pencils where the axle holes are. This will prevent paint from pooling around the bottom of the body.
Insert toothpicks into the axle holes, and have your racer spray a light coat of primer over the body, holding the can 8-10" away from the body and painting with slow, smooth strokes.
After it dries, get another sheet of 2000 grit sandpaper and have your racer sand every side except the bottom until he says, "Holy cow! I didn't know wood could feel this smooth!"
Insert toothpicks into the axle holes, and have your racer spray a light coat of primer over the body, holding the can 8-10" away from the body and painting with slow, smooth strokes.
After it dries, get another sheet of 2000 grit sandpaper and have your racer sand every side except the bottom until he says, "Holy cow! I didn't know wood could feel this smooth!"
Lively Livery
A race car's paint scheme is called a livery, and now we're going to apply a livery to your car. Here are my four favorite ways to paint a car:
Solid Color
Insert toothpicks into your axle holes, get a can of Rust-Oleum Painter's Touch 2X Gloss paint in your favorite color and have your racer apply it like he or she did with the primer: light coat, slow and smooth, holding the can about 10" from the body.
Let it dry for 24 hours.
Get some 3000 grit wet or dry sandpaper and sand the body while holding it under running water. That will wash all the tiny particles away.
Dry it with a microfiber cloth or a t-shirt and let it dry.
Insert toothpicks and apply a second coat of color and let it dry for 24 hours.
Get a can of Rust-Oleum Painter's Touch 2X Gloss Clear paint and, after inserting the toothpicks, add a coat of clear. Let it dry for about 30 minutes, do not sand it, and add another coat of clear. Let it dry about 30 minutes, do not sand it, and add a final coat of clear. Let it dry for 24 hours.
Racing Stripes
My favorite way of adding racing stripes is by painting the solid color like I already mentioned then applying Maximum Velocity pinstripes. They have nine colors to choose from, including chrome.
Color Fade
It's easier than you think to make a car where one color fades into another.
Follow the steps for painting a solid color car except after you paint the first color, take a sheet of paper and tape it to the cardboard box to create a curved cover over half of your car. The closer the paper is to your car, the shorter the fade will be.
You can test it on scraps of wood or paper to get the fade just right before painting your car.
Flames
Maximum Velocity also has some great stencils for painting flames on your car. You'll start by painting your car the color you want the body to be, then apply the stencil and paint the flames. You could use the stencil in combination with the color fade technique to paint some amazing fading flames on your car.
Now that you know what a livery is, did you know that the circle where they put numbers on old race cars is called a meatball?
Axles
You can spend a lot of money on highly-modified axles, but it's pretty easy to clean up the ones that came with your kit with this Micro-Polishing System and Diamond Finishing Kit from PineCar.
Get some XLR8 Ultra Graphite from PineCar, your your axles in a small Ziploc-type bag, and shoot some graphite into it. Zip it up and shake it around to get the axles covered.
Wheels
If you're in Boy Scouts, you're probably using solid BSA wheels.
You can do a lot with these wheels but honestly, I just buy a set. Derby Evolution offers them in 10 different colors, including glow-in-the-dark and fluorescent colors that glow under blacklight, and with varying levels of modification to fit your rules and budget.
Knight Rider style with the trim ring and axle head painted with paint pens.
British vintage with the trim ring and spokes painted chrome (or silver).
Vintage cruiser raised white letter.
Tron-inspired fluorescent with black centers.
Indycar style with a red trim ring.
White wall - start with glow-in-the-dark wheels, color the tread area with a black Marks-A-Lot chisel tip marker, and fill in the wheel with a red Sharpie.
If you're in another organization, you're probably using spoked PineCar wheels.
The options on these wheels are a little more limited, but I love the way they look. Get a set of Precision Stock Wheels from PineCar.com. They're modified for speed and they look incredible with the spokes and trim ring painted chrome with a paint pen.
Muscle Racer - Chrome trim ring and center hub with metallic gray spokes.
Street Muscle - Chrome trim ring with black spokes. Would also look great with chrome spokes.
Wheel Installation
When you install the wheels, shoot some graphite into and around the bore - anywhere the axle or axle head will touch the wheel.
Gently insert the wheel and axle into the axle holes, leaving a gap of about 1mm between the body and the wheel. I usually use the rounded end of a screwdriver to push it in until I get to that 1mm gap.
Weight
Remember that it's easier to add weight than to remove it. You'll want to get your car to 4.6-4.8 ounces at home and add the rest at inspection.
Get this scale. Your analog food scale isn't going to be accurate enough. This one goes to the five one-thousandths of an ounce and the lid detaches to serve as a tray.
If you have access to a drill press and you drilled that 1" hole in the bottom of your car, get this round tungsten weight from Maximum Velocity. Glue it in with the slot facing out. When you get to the race, you can insert the weight cubes to get your weight as close to 5.0 ounces as possible.
If you do not have access to a drill press and you drilled cylindrical holes in the back of your car, get this tungsten cylinder set from Maximum Velocity.
Put the scale tray on the scale and turn it on. Put the body, wheels, and axles on the tray, then add weights until you get to 4.6 ounces. Insert the weights into holes, distributing them equally, then fill the holes with sandable paintable wood filler and let it dry. Return to the Sand and Seal section.
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