Wax Those Wheel Bores for Top Performance

By Randy Davis

If you peruse the various pinewood derby forums, you will know that
the adult racing leagues are highly competitive. These pinewood derby
car builders are always on the lookout for techniques to gain a few
milliseconds. The first article of this season discussed one of these
techniques, the use of fenders to improve the aerodynamics of the car.
Today we will look at another technique, waxing the wheel bores.

Polishing wheel bores is fairly common, and is accomplished using a
product such as Micro-Gloss(1), a very fine crystalline abrasive that
is designed to polish plastic and acrylic products. Waxing the bore
goes a step further by applying a plastic-safe wax (Pro-Bore Wax(2))
and then buffing it with a pipe cleaner. This wax fills in tiny
imperfections in the bore and results in a hard slick surface that is
better than the polished bore. To check this out, let’s run an
experiment and see what happens.

EXPERIMENT SETUP
In order to isolate the benefit of waxing the bore, all other
variables need to be eliminated. Therefore, track testing would not be
a viable way to test as too many factors are at play. So instead, we
will use a weighted-wheel spin jig. The equipment used was previously
described in Volume 8, Issue 6 – Grooved Axles.

As a refresher, the apparatus consists of a machined steel ring which
is sized to fit snuggly over a machined BSA wheel. The ring weighs two
ounces, which is essentially the load on a rear wheel of a pinewood
derby car.


Figure 1 – Weighted Wheel Spin Jig

After sliding the ring over the lubricated wheel-axle assembly, the
axle is mounted onto the apparatus. A length of nylon line with a
weight on one end is wound around the ring (there is a small pin on
the ring not seen in Figure 1, to which the non-weighted, looped end
of the string is attached). On each test, the string is wound until
the weight touches the eye hook. The weight is then released and a
stopwatch is used to measure the spin time. The string is sized such
that it is released from the ring before the weight reaches the
ground.

Two wheels and two axles were used for each test. The reason for the
duplication is to ensure that performance is not exaggerated or
degraded due to a “fluke” wheel or axle. The wheels were machined
wheels and were from the same mold number.

The combinations tested were:

Max-V-Lube Graphite – No Wax
Max-V-Lube Graphite – Pro-Bore Wax
Krytox 100 – No Wax
Krytox 100 – Pro-Bore Wax

Each wheel/axle was lubricated in the same manner, and then given two
break-in spins. Next, five spin tests were performed for each wheel
(eight wheels total).

EXPERIMENT RESULTS
As you can see in Figure 2, the use of Pro-Bore Wax improved the
performance for both Krytox 100 and Max-V-Lube Graphite (a longer spin
time is better).


Figure 2 – Experiment Results

How does this data transfer to track time improvement? Certainly the
improvement in track time would be much smaller than shown above, as
many other factors come into play. However, with both lubes, using
Pro-Bore Wax should provide measurable differences on the track.

(1) Bore Polish (Micro Gloss) can be found Here.

(2) Pro-Bore Wax can be found Here.

From Pinewood Derby Times Volume 13, Issue 5

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Maximum Velocity Pinewood Derby Car Plans and Supplies

Think Safety while Building Your Car

(Updated from the original article published in Volume 1, Issue 4, November 14, 2001)

A few weeks ago, I was working in our shop and – through foolishness on my part – managed to slice open a finger. After an expensive trip to an urgent care center, I was the owner of several stitches. Needless to say, safe workshop practices came to the forefront of my mind.

So, to kick off this year, I would like to provide some safety guidelines for working on your car. Please bear with me, and read this information. A refresher course in safety never hurt anyone, and it could save you or a member of your family from getting hurt. Also, as parents we need to teach our children to work safely by modeling good safety practices and making sure they take safety precautions seriously.

PROTECT YOUR EYES
I am sure everyone reading this has had some foreign material get into an eye, and many of you have had a scratch on the surface of your eye. As you found out your eyes are very sensitive, and easily damaged. While working on your car all manner of material will fly around so ALWAYS WEAR EYE PROTECTION. Two types of eye protection are available for a reasonable price at hardware and homes stores: safety glasses and safety goggles.

Safety glasses have clear protective lenses with side shields. They are used when you don’t wear glasses or when you wear contact lenses. They have adjustable temple pieces to fit your head, but can also be purchased on-line in children and adult sizes.

Safety goggles have a clear protective lens and fit over regular glasses. Safety goggles do a better job of keeping floating dust out your eyes than do safety glasses. So, even if you don’t wear glasses, you may want to consider safety goggles. Consider wearing safety glasses when drilling, sawing, chiseling, etc., but wear safety goggles when sanding, painting, and using graphite.

I know that eye protection is a hassle to wear, but don’t risk your eyesight over a little comfort. An emergency room visit to remove a wood fragment from your eye is an experience you want to avoid.

PROTECT YOUR LUNGS
You will create a considerable amount of wood dust while working on your car. Don’t breathe that dust into your lungs. Instead, WEAR A PARTICLE MASK whenever you are sanding, filing, drilling, or lubricating with graphite. Also, when spray painting, work in a well-ventilated area, and wear breathing protection.

Most home supply store sells two types of particle masks. The first type, a Comfort Mask, is less expensive. It is made of a relatively thin material, has one thin rubber band to secure the mask, and does not have a seal on the edge of the mask. The other type of mask is intended for drywall installers and painters, and is sometimes referred to as a Particulate Mask. This mask is thicker, has two sturdy rubber bands, has a seal around the edge, and is slightly more expensive. Admittedly the Comfort Mask is more comfortable, but it does a poor job of filtering sawdust. I strongly recommend using a Particulate Mask.

When spray painting, consider using more serious breathing protection. Hardware and home store offer breathing masks with replaceable filters. These remove more particulates, and some of the harmful paint fumes.

PROTECT YOUR HANDS
During my junior and senior years in high school, I worked at a custom woodworking mill during the summer. I personally had several close calls with power tools, and witnessed a few injuries.

In one close call, a table saw (with the safety guard removed) kicked-back a large sliver of wood which embedded itself in a board across the room. Fortunately no one was in the way. In another case, a different saw kicked-back a sliver that went through two fingers of the operator’s hand. Fortunately the wood missed the tendons, and he regained full use of his hand.

The point of this is to encourage you to BE VERY CAREFUL WITH POWER TOOLS. Make sure you know the proper way to use the tool and don’t remove the safety devices.

There is also one non-power tool to be very careful with – the wood chisel. Wood chisels need to be very sharp to work properly, and considerable force must be applied to the chisel to gouge out the wood. Both of these characteristics (sharpness and force) can lead to gouges in your hands. When using a chisel, ALWAYS POINT THE SHARP END AWAY FROM YOUR BODY. At a pinewood derby workshop two years ago, a parent was using a wood chisel and failed to follow this warning. He proceeded to slice open the palm of his hand, requiring a visit to the emergency room, and a significant blood clean-up operation in the shop.

PROTECT YOUR HAIR
Even after more years than I care to remember, I will never forget a photo that hung by the drill press in the machine shop at our high school. The photo showed a mass of hair mixed in with metal shavings, lying on the table of the drill press. Someone with long hair had used the drill, the loose hair got caught in the drill bit, and … well, you can imagine the rest.

The clear lesson is to SECURE LONG HAIR when working in the shop, especially when using any revolving tool (drill, power saw, etc.). Also don’t wear necklaces, bracelets, scarves, and other loose articles (including clothing) while working on your car. Any loose article can get caught in a revolving tool, leading to serious repercussions.

USE CAUTION WITH LEAD
Although other metals are available as ballast weight, due to the low cost and high-density, lead is still the most common weighting material for pinewood derby cars. But as you probably know, lead is toxic if taken internally. Therefore:

– Wash your hands after handling lead (and don’t put your fingers in your mouth).
– Keep lead away from food, water, and food preparation areas.
– Collect and properly dispose of any lead pieces.
– Don’t sand or saw lead (creates particles). To cut lead, use cutting pliers or use a hammer to drive a flat blade screwdriver through the lead.
– Don’t melt lead. Not only are the fumes toxic, but the lead could pop or splatter and cause a severe burn. Also, if melted lead is placed directly into a cavity in the car, it will cause the wood to smolder and can ruin a nice paint job.

A FINAL THOUGHT ON SAFETY
Oftentimes, accidents occur when people are in a hurry. In the rush to complete the task, good judgment is put aside, which greatly increases the chance for an injury. So, don’t wait until a few days before the race to build your car. Instead, plan ahead and get started as soon as possible. By working slowly over time, you will work more safely, and the end result will likely be a better car.

I wish all of you a wonderful and safe derby experience.

P.S. Okay, I’ll tell you how I cut my finger. I was using a drill press to drill a somewhat large hole in a strip of sheet metal. When doing this kind of drilling, the sheet metal must be securely clamped to the drill press table (or the work surface if using a hand drill). I knew this, but thought to myself, “I can hold it.” Stupid me. Of course, the drill bit ‘bit’ into the metal, easily snatching it from my grasp, and proceeded to wield the sheet metal like a revolving knife blade. You can imagine the rest. I was fortunate to only get one finger cut.

From Pinewood Derby Times Volume 7, Issue 1

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Maximum Velocity Pinewood Derby Car Plans and Supplies

Pinewood Derby Car Showcase – November 22, 2013

Today’s cars are from Don Brown.

In August of this year the National Sprint Car Hall of Fame and Museum
in Knoxville, Iowa held its first inaugural National Pinewood Derby
race. The rules were quite simple: 5 ounces maximum weight, must be
sprint car appearing with the wings from the Revell sprint car kit,
and must have four wheels.

I purchased three Revell kits and did some serious work to make the
cars look like a current sprint car. After the bodies were shaped,
sanded, painted and weighted, I called on my good friends at Maximum
Velocity for the best wheels and axles. The car I entered in the race
used SS needle axle wheels with the needle axle upgrade kit. I
countersunk the SS wheel to accept the bead retainers (I found out
that the race required wide wheels). The other two cars have X-Lite
needle axle wheels. After some polishing and fine tuning, the cars
ran straight and fast.

Cars showed up from all over the country for a fun afternoon of racing
at the Museum. I’m proud to say that at the end of the day our
Halibrand-sponsored, red, white and blue sprinter won the “A”-main and
was crowned National Champion.

Sprint Car 1

The National Champion car. Parts were added from a plastic model. I
also narrowed the car body and used metal tubes to accept the needle
axles.

Sprint Car 2

Sprint Car 3

From Pinewood Derby Times Volume 13, Issue 4

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Maximum Velocity Pinewood Derby Car Plans and Supplies

New Pinewood Derby Products from Maximum Velocity – 11/18/13

It’s heading into the holiday season, but that also means it’s pinewood derby time. Just in time for derby season, we are announcing several new products and some special offers to help you have a great race.


Pro-Bore Wax: This plastic-safe wax will put a mirror-like shine on the wheel bore, reducing friction and improving performance. Click Here For More Information

Pro-Axle Bender: This new tool from DerbyWorx provides an accurate, simple, and repeatable way to put a bend in pinewood derby axles. On typical axles, the tool supports any angle between 1/2 and 8 degrees. Click Here For More Information


Pro-Stainless Steel Axles: These CNC-machined axles are formed to resemble Cub Scout axles, but with a two-step shaft for a good fit with axle slots or holes, and an excellent fit with the wheel. The axles have a tapered head, no burrs and crimps marks, and are made from a high quality stainless steel for increased strength, and reduced friction. Both grooved and non-grooved versions are available. Click Here For More Information


Guide Fin[: When rail-riding, the front raised wheel is just dead weight. Replace it with a Guide Fin, and add the saved weight where you want it.
Click Here For More Information


Car Canopies (2 for the price of 1): Dress up your car with a large or small canopy, or use both! Simply cut out a canopy and glue it to the car with epoxy or canopy glue. For a unique look, paint the inside to match or compliment your car’s finish. Click Here For More Information

We have many other new products as well. You can see all of them Here

== A Gift For You ==
To thank you for your continued patronage, we have a gift just for you. To receive a free Tapered Underbody Weight, please add one to your shopping cart Here
This free gift is available through December 3, 2013.

== Specials ==
In addition to the gift, our Pro-Bore Wax is on sale for $1.00 off. To get this special offer, Click Here:

Finally, you can also get 10 percent off your entire order. Just use coupon code:
2013NOVTENOFF
on the shopping cart page. This discount code is good through December 3, 2013.

== Inventory Clearance ==
We also are clearing inventory on several items including our ropeller Car Kit II, the Assimilator Kit (with a tungsten canopy), and a special edition Funny Car Kit. We don’t have many left, so don’t delay. Click Here to find our clearance items:

As always if we can help in any way, please contact us by e-mail at:
info@maximum-velocity.com

Best wishes to you and your family for a great pinewood derby racing
season.

With best regards,
Randy Davis
Maximum Velocity – Give Your Car The Racer’s Edge!

Days of Thunder

By Greg Wallace

I attended a masculine, macho, testosterone-fueled gathering recently.
An event where only the most manly of men dare to show their rugged,
brawny faces. That’s right, I went to my daughter’s Girl Scout
Powderpuff Pinewood Derby race and picnic.

For those of you unfamiliar with what a Pinewood Derby race is, allow
me to explain. In this particular case, all the little girls in my
daughter’s troop were given a Pinewood Derby kit that they were to
assemble and decorate with a supervising adult. The kit consists of a
block of wood (presumably pine), four plastic wheels and four small,
silver nails, hereafter referred to as “axles.” The supervising adult
helps to shape and paint the car and apply the wheels and “axles” so
the little girls don’t hurt themselves or have to have a turpentine
bath. The girls then all gather together to show and race their cars.
Afterward, trophies are handed out for the fastest cars and the Best
of Show. Then you eat hot dogs, hamburgers, pasta salad and brownies.

If you ever want to see a group of guys on edge, try attending a
Pinewood Derby race with a bunch of dads. I watched as they stood
around the display table prior to the race. I can compare it to a
group of NASCAR owners pacing along pit row before the Daytona 500.
They all discussed among themselves what kind of band saw they used to
rough out the shape of their car, how many coats of primer and sealer
they had used to paint it, and where they placed the weights on the
car to bring it up to the 5 ounce weight limitation. Most of all they
talked about the amount of hours they spent sanding and polishing the
aforementioned “axles” to get them to a glass-like finish and just
what brand of graphite to use to make those “axles” even faster. They
were all nervously sizing up the competition. No father wants his
little girl to lose. He wants all the other fathers’ little girls to
lose.

I am proud to say that I was not a part of this high-strung group.
Nope, I didn’t have a care in the world at that time. In fact, I was
much more concerned about the hamburgers. They smelled really good.
You’re probably wondering to yourself why I was so calm, cool and
collected. Well, this was not my first Pinewood Derby. No, I have a
long history of building little cars out of wood and I was fairly sure
about how my daughter’s car would perform that afternoon.

I did some mathematics this past week. That may not seem like a big
deal to most of you but keep in mind, I was an art major. In the year
1973, I was in my first year of Cub Scouts and my dad and I made our
first Pinewood Derby car. For means of full-disclosure, it was
actually a truck. It was yellow and red with sky-blue windows. I can
still picture it majestically sitting atop the Pinewood Derby track.
Words alone cannot come close to describing its beauty. In my first
heat of my first Pinewood Derby race, my yellow truck streaked out to
the lead of the other three cars in the heat and barely held on for
the win.

Now you should know that in the world of competitive Pinewood
Derbying, the races are based on a triple-elimination basis. As long
as you win, you’re okay and you get to keep racing. As soon as you
don’t win three times, you’re done.

With that first win under my Cub Scout belt, I was on top of the
world. I was unstoppable. But just to be on the safe side, before my
next race, I decided to squirt some more graphite on the “axles.” In
my mind, my yellow truck would only become faster. But for some
unknown reason, maybe it was a chemical reaction, atmospheric
conditions, or as I have claimed throughout the years, dastardly
sabotage, my truck got slower. In fact, when they dropped the starting
gate on my next race, Old Yeller just sat there while all the other
cars roared down the track. That first win would prove to be my last.
Throughout the rest of my Cub Scout career, I would never again
experience victory as I would always be three races and out.

And then my son became a blue and gold neckerchief wearer. I thought
that this would be my chance for redemption. But alas, in all his
years of scouting, although we took home trophies for Best of Show,
our cars were always out after three races.

Now here we were, on a breezy Saturday afternoon in 2013, 40 years
after my first taste of Pinewood defeat. Yeah, I was pretty sure how
my daughter’s car would perform. I joked to my wife that the car would
probably go faster if we would have left it in the box. But I kept a
smile glued on my face as my little girl proudly approached the
starting line with her hot pink car. It may be wrong, but I prayed as
they dropped the starting gate.

On the way to the race, I explained to my daughter that winning wasn’t
everything. I told her that she probably shouldn’t expect to win and
that she should just try to have fun. She assured me that she would be
happy no matter what the outcome.

As her car finished in third-place, I realized that my daughter is a
little bit of a liar. The steely glare that she gave me, made me
realize that happiness was not on the menu. As she sullenly sat on the
park bench waiting for her next race, I could tell she was determining
the type of nursing home she was going to place me in someday.

As she approached the starting line for her second race, I was trying
to figure out my escape plan. Her car might not have been the fastest
but I was pretty sure she could pummel me with it. As the cars started
down the hill, I silently said another prayer. Through my squinted
eyelids, I saw a flash of hot-pink cross the finish line in first
place. We had done it! The curse was over! Four decades of defeat were
in my rearview mirror! I might get to go to a slightly nicer nursing
home!

When the day was over, she ended up winning one more heat before
ultimately ending up in the top seven cars. I don’t think she truly
understands what those two wins represent, but I do. The forty years
of shame and humiliation that I brought upon the House of Wallace were
over. It was a good day.

And the hamburgers were delicious.

Greg Wallace writes a column for the Bureau County Republican
newspaper in Princeton, Illinois. You can follow Wallace’s blog at
gregwallaceink.blogspot.com
Used by permission.

From Pinewood Derby Times Volume 13, Issue 4

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Maximum Velocity Pinewood Derby Car Plans and Supplies

Pinewood Derby Car Showcase – November 12, 2013

Low-Rider – Paul & Jordan Messineo

Jordan is 9 years old, and for two years he entered the Derby only to come in last each year. He went to his dad and said enough is enough; he wanted to at least be competitive. Dad enlisted grand pap and stated the problem. Papap went online and found Maximum Velocity, who helped with a lot of the details. Guess what? Jordan came in 1st out of 50 cars. That was last year, now everyone in the district was waiting for the latest entry of Jordan’s. Jordan showed up with a great running Wedge car that looked like a winner. However, the rules were modified and Jordan’s father did not receive the changes due to his out of town travels. The Wedge car had three wheels touching, and the rules clearly stated that all four wheels had to touch. When Jordan showed up with his father, one hour before the race they were told of the rule changes and the car was declared ineligible. Jordan was devastated and heartbroken. Papap and Dad went back home and decided to look at the other cars that Jordan had built to see if anything could be done. Jordan’s brothers, Paul III and Brandon, worked on this previously built Low-Rider (with Papap and Dad) to lower the fourth wheel. With only 22 minutes remaining they completed the revision and started back to the race. They arrived with only 6 minutes remaining and checked in with the revised Low-Rider. The car was carefully checked by the officials and passed.

The race started, and low and behold Jordan finished second. This was quite an accomplishment considering the work that had to be done in order to compete. Well compete they did, what a lesson in life this taught Jordan, NEVER GIVE UP!

But the story does not end here. The following week Jordan entered the Pittsburgh Council regional event with the same car and took 1st in Webelos and 2nd overall. What a great time Jordan had in telling this story – three trophies in two weeks!

Wii – Jim, Josh & Jake Heidecker

Josh (1st year Webelo) and Jake (Bear) had selected your Wing design for their car this year but were not sure how they were going to paint it. Both really wanted a Nintendo Wii game console for Christmas – when I mentioned that the controller for the game was about the same size as their pinewood derby cars, they got the inspiration for this design. With the help of the speed tips we learned from your site, Josh came in 1st and Jake came in 2nd out of 66 cars! The attached picture is Josh’s car; Jake’s was similar except it was white.

Dale Earnhardt’s 1998 Daytona 500 Winner – James Gravely

Last year was my son’s last year of scouting, so my last hold on pinewood derby racing is gone! I love pinewood derby racing, and am now thinking if I want to ask my wife to have more kids. My only problem is I would have to wait five years before they could join Cub Scouts and, oh my, suppose they were girls!? Well let’s just forget that idea (for now).

Anyway, while my son was in Cub Scouts, every year we came up with the most exciting concept that we could (actually I hoped my son would let me decide on the design because his were more intricate than mine, and I knew I would have great difficulty fabricating his desires).

This car is a replica of the late Dale Earnhardt’s 1998 Daytona 500 winner, complete with all the correct details. The car would have been our 2007 entry if my som was still active in Cub Scouts. I built the entire car myself with no help from my son since it was not intended to be raced. The car is built to specification and is completely legal for derby racing: correct wheels, axles, weight, and size dimensions. The car is bathed in ‘Racer Black’ lacquer, and the decals and paint are protected by five coats of clear gloss top coat.

From Pinewood Derby Times Volume 6, Issue 15

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Maximum Velocity Pinewood Derby Car Plans and Supplies

Top Fuel Cars: Propeller Car

(The third in a series of articles on cars that ‘stretch the rules’ – this is an updated version of an article that first appeared in Volume 3, Issue 5, November 26, 2003)

Many organizations give parents and siblings an opportunity to race by sponsoring an open competition race. Typically the rules for these races are somewhat relaxed, allowing more innovation and creativity in car design.

In today’s article I would like to first share some typical ways to ‘open-up’ the rules for this type of race. Then I would like to explore a more radical way to add excitement to your derby event.

RULES FOR OPEN COMPETITION RACES

Here are some common ways to allow more flexibility in open competitions:

1. Wheelbase – If the organization event mandates the use of a standard wheelbase (distance between the front and back axles) then allow the wheelbase to be modified as desired, as long as the overall length specification is maintained.

2. Alternate axles – Instead of requiring the use of the organization standard axles, allow the use of after-market ‘speed axles’.

3. Wheel shape – Typically, standard rules allow minimal wheel modification (e.g., only a light sanding). Try removing this restriction, allowing any plastic wheel, as well as any wheel treatment including narrowed, grooved tread surface, and/or overall weight reduction.

4. Length – Try changing the maximum length from the typical seven inches to twelve inches (or one inch less than the distance from the starting pin to the back edge of the track).

5. Weight – Consider changing the maximum weight to one or more pounds (with standard wheels and axles, I don’t recommend exceeding 1 pound).

A MORE RADICAL APPROACH

Wouldn’t it be fun to add a whole new dimension to your open competition? I’m thinking power!

Okay, I know what you’re thinking. Someone will strap a rocket engine on the car, and the car will damage the track, a person, or the building! But of course, restrictions would be necessary to minimize any risk. So, I suggest the following rules.

Rules for a Radical Open Competition

Dimensions
(Adjust to fit your track, and leave an open lane between cars)

– 11 inches maximum length
– 5 inches maximum width
– No limit on height (remove the electronic finish line)
– 3 inches maximum inside wheel base
– 3/8 inch minimum track clearance
– 16 ounces maximum weight

Power Sources
In addition to gravity power, other power sources may be used as long as they do not pose a risk to the spectators or to the track.

1. Allowed power sources include, but are not limited to electrical, mechanical, and pneumatic.

2. Power sources which use combustion of any type are explicitly disallowed. This includes combustion engines, rocket engines, and explosives.

Wheels, Axles and Body
A pinewood derby kit may be used, but it is not required. Any material can be used for the car as long as the finished product meets the specifications. However, the wheels must be made of a material that will not damage the track. Metal, ceramic, glass, or other hard substances may not be used for wheels. Allowable materials include plastic, rubber, and wood.

Race Procedure
The owner of each car will stage the car on the starting line, and pick the car up at the end of the run. Cars may be adjusted between races as long as the adjustment does not delay the race. However, cars may not be lubricated during the race.

Possible Designs

I have heard of all sorts of ideas for adding power to pinewood derby cars. Listed below are a few that have merit.

Powered Rear Axle
– Spring wind-up mechanism
– Rubber-band powered
– Mouse-trap powered
– Electric motor powered (R/C type)
– Weight powered (suspended weight drops and turns rear axle)

All of these ideas can be made to work. But two problems must be worked out:

1. How to apply power when the starting pin drops, or
2. If power is applied before the pin drops, how to apply the maximum torque without the wheels spinning-out.

Non-powered Rear Axle
The design ideas below eliminate problem number two above, but problem number one must still be resolved.

– Compressed CO2 or Air (acts like a ‘jet’ engine)
– Propeller powered (push or pull)

PROPELLER POWER

I have had some experience with propeller power, so I would like to share the design of three cars that I have built. The first one was built in 2002, the second in 2005, and the third in 2007. I have also included photos of a few propeller cars submitted by readers.

First, here are some principles that I have learned through experience.

1. Maximize thrust through higher RPM motors, steeper blade pitch, and larger props.
2. Maximize acceleration by minimizing weight. This mainly means lighter weight batteries.
3. The longer the track, the greater the speed (and the larger the advantage over conventional cars).

My First Propeller Car

Please don’t laugh too hard; I severely over-engineered this car. But I can say the car has never had to be repaired! This car smoked the competition when it raced in 2002, and it easily beats any standard pinewood derby car (2.7 seconds on a track measuring 33 feet, 3 inches from the starting pin to the finish line – measured with a stop watch as it doesn’t fit under the finish line bridge).


First Car: Front View


First Car – Rear View

Here is a parts list and some notes on implementation.

– Motor: 12 VDC motor, RF-370CA by Mabuchi Motors. This is a VCR motor, but other motors would work as well. I drove the motor at 18V for more power. This would eventually burn out the motor, but the on-time is so short that the motor doesn’t get a chance to overheat. This motor is available at:
http://www.jameco.com
Jameco’s part number is 238473


Motor Diagram

– Motor Mounting: The two screw holes on the front of the motor are for mounting. The required ISO screws can be purchased at a hardware store. I used a piece of thin stainless steel (hardware store item), drilled holes for the mounting screws, shaft, and assembly bolts (see front view picture).

– Propeller: I used a plastic prop intended for rubber band powered airplanes. The hobby store I visited sold them in packs of three. The prop is about 5 inches long, and I had to trim the tips a bit for clearance. The shaft hole was too small, so I drilled it out to fit snuggly on the motor shaft. I then used epoxy to glue it in place. I believe this type of propeller works better than an R/C airplane propeller. R/C propellers are heavier, and the blade angle is smaller, providing less thrust.

– Infrastructure: I had access to an old erector set, but you can use any light metal strapping. It does need to be securely mounted as some torque is generated. Make sure there is clearance for the propeller. I had to remove some metal from the erector material. If you look carefully at the front view, you can see where it was removed.

– Motor Shroud: Quaker Oats oatmeal container. I put this on for two reasons: (1) To keep hands from touching the blades (it hurts, but doesn’t cut if you touch the spinning blades), and (2) To keep the blade from breaking if the car rolled over – if the blade comes off, the race if over.

– Motor Alignment: The motor does need to be pointing as straight forward as possible. Add/remove small washers where the stainless steel strap fastens to the infrastructure to adjust alignment.

– Starting Pin Switch: I used a contact switch (part #275-016 at Radio Shack). It is normally on. When the car rests against the starting pin, the weight of the car closes the switch turning the motor off. Thus, when the pin drops, away it goes.

– Kill Switch: If you look carefully at the front view you will see a small toggle switch (part #275-624 at Radio Shack) that is used to turn the motor off when not in use. Just make sure to turn it on at the starting gate!

– Batteries and Holders: Two standard 9V batteries. The battery holders are Radio Shack part #275-326.

– Wiring: Light gage electronics wire. Positive side of the battery goes to the Kill Switch, then to the Starting Pin Switch, then to the motor. The negative wire goes to the motor. Batteries are wired in series.

– Wood: Pine, 1-3/4 inches wide. The car is 10 inches long, but it could be shortened.

– Wheels/axles: Standard BSA issue. Axle holes are drilled with a drill press. All four wheels touch the ground.

My Second Car
After seeing the propeller cars built by others, I decided to build another car. This one would be less bulky, but would use the same basic components. The main differences are the use of Outlaw Wheels, the full 5 inch long propeller (did not need to be shortened), and significant weight reduction.


Second Car: Front View


Second Car – Rear View

With the reduced weight the performance improved significantly, completing the same distance as prop car 1 in 2.2 seconds, 1/2 second faster than my first car (again measured with a stopwatch). But remember the reason for the oatmeal container on the first car? Sure enough, on the second run, the car tipped over on the braking section, and the propeller flew off. So the lesson is that if you run this type of car, keep the finish line area clear of people (to avoid an eye injury), and have someone stationed at the end to catch the car and turn off the motor.

My Third Car
I decided I needed to build a car that fit within the standard dimensions, so that it would go under the finish line bridge. After a reader posted some information on a derby forum, I decided to do this with a ducted fan from an R/C ‘Jet’ plane (purchased from Hobby Lobby). To get a high enough RPM, I used a 7.2 V Speed 300 compatible motor that was intended for an R/C boat. The motor is powered at 9 volts. The two batteries are wired in parallel to provide enough current for the motor.


Third Car: Front View


Third Car – Rear View

This car is loud and fast, but not quite as fast as the second car. It runs the same course in 2.3 seconds. I believe the speed could be improved with a smooth ring around the intake (like on a real jet engine). According to the documentation that came with the duct fan, this can improve thrust by as much as 25 percent.

READER SUBMITTED CARS
Here are a few propeller cars sent to me by readers.


Keith Gosselin – Like my car, this one has a starting pin contact switch and a kill switch. Hanging the propeller (tri-blade in this case) off the back of the car permits the use of a longer propeller.


Mark Pugsley – A similar design using a rubber band airplane propeller (and liberal use of rubber bands in the infrastructure).


Unknown – A dual prop model that uses an R/C type battery and control. It appears to be quite heavy, so I am not sure how will it performed. (This photo was sent to me by another participant in the race. If this is your car, please let me know so that I can give you credit).


Unknown – (If this is your car, please let me know so that I can give you credit).

CONCLUSION

Maybe this all seems a bit ridiculous to you. But I guarantee that if you have a group with a lot of handy parents, an open competition race with power assist is a blast and a certain crowd pleaser!

From Pinewood Derby Times Volume 6, Issue 15

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(C)2013, Maximum Velocity, Inc. All rights reserved.

Maximum Velocity Pinewood Derby Car Plans and Supplies

Pinewood Derby Car Showcase – November 5, 2013

Today’s showcase cars are from Donald Welsh.

Pink Phantom

Here is the car that my daughter Laiken and I built for this year’s
Awana Grand Prix. We found the Formula One design at Maximum
Velocity; my daughter liked it because it was cool looking. I was not
too surprised when she decided to paint it pink and add the colorful
decals. The car ran really well in practice and raced really well in
the derby to earn third place for speed in the TnT girls division.
This was her first time racing in the derby and she was very surprised
when they called her name at the end of the derby for her trophy.

Riddler

Here is the car that my son Luke and I built for this year’s Awana
Grand Prix. The Riddler took second place for speed in the TnT boys
division. The car is the extended version of the Maximum Velocity Wing
design. Luke painted it green and I painted the questions marks on
using a Styrofoam plate with the cutouts. We decided to make his car a
three wheel runner, and after hours of sanding and polishing the axles
and wheels it produced really good results.

Vaccinator

I built this Maximum Velocity Vaccinator design to race against my
children during practice. The car is very quick. Everyone at the
practice runs thought it was the coolest car they had seen and some
were worried that it would be entered in the derby. After seeing this
car on Maximum Velocity I couldn’t imagine it being any other color.
The paint job is not perfect but it is a sweet car and my son said he
wants to make one for next year’s derby.

From Pinewood Derby Times Volume 13, Issue 3

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Maximum Velocity Pinewood Derby Car Plans and Supplies

Shop Talk – Woodworking Tips for Pinewood Derby Car Building

When I was a boy, my father was involved in several home remodeling projects. At the time I was more interested in goofing off than learning carpentry, electrical wiring, plumbing, etc. I did learn the basics, but now as an adult, I wish that I had paid more attention so I could do more of my own work.

During the work sessions with my dad, he would pass along some tips to make the job go easier. The few I remember (and still strongly adhere to) are:

– Measure twice, and cut once.

– If you are going to buy a tool, spend the extra money to buy a good one. Good tools work better and last longer. Cheap tools just make the job harder.

– Don’t get ahead of yourself. Take it one step at a time.

These tips are certainly true for any woodworking project, and I try to apply them to home projects as well as pinewood derby car building. But of course, this is just the tip of the iceberg for useful woodworking tips. So, what I would like to share today are some
woodworking tips that I have learned over the years that really help when applied to pinewood derby car building.

MEASURING AND MARKING

Incra Bend Rule

– Use an accurate ruler and measure carefully.

– When marking drilling locations, make a slight indent at the drilling location with a sharp pencil.

– Use a square to draw lines perpendicular to the block (don’t eyeball it).

– Generally, lines for cutting are drawn so that they remain after the cut. They can then be sanded away.

DRILLING/POCKETING

Hand Drilling
– Clamp the wood block in place. Don’t attempt to drill with one hand while holding the block with the other.

– Drill straight down with the drill no higher than chest level. If needed stand on a step stool to get the needed height.

– Use steady, even pressure on the drill. Pushing too hard can result in deeper holes than desired.

– For holes that do not go through the block, mark the drilling depth on the drill bit with a piece of masking tape.

– When drilling completely through the block, put a scrap piece of wood underneath the block. This will minimize chipping at the drill bit exit site.

Drill Press
– Use a vertical fence to set the offset from the bottom/edge of the block to the drilling location.

– Enter the wood slowly to minimize chipping.

– For deeper holes, drill part way through, retract the bit to clear the debris, then drill the rest of the hole.

Chiseling a Pocket
– Remove most of the wood with a drill.

– Clamp the wood block in place. Don’t attempt to chisel with one hand while holding the block with the other.

– Use a hammer and chisel together to make the first chisel cuts around the edge of the hole being chiseled.

– Tap the chisel gently, and remove a small amount of wood at a time. Taking too big of a bite can cause the wood block to split.

– Use the chisel by itself to remove any wood in the center of the hole.

– When removing a thin shaving, a hammer is not needed. Just push the chisel with steady pressure.

– Keep the chisel sharp to avoid splitting the wood, and most importantly, keep all body parts away from the cutting edge.

SAWING

– Make sure the wood block is clamped in place before cutting with a hand saw.

– When using a coping saw, make sure the blade is tensioned tightly.

– Start the cut by making short gentle strokes. When the saw is firmly in the wood, take longer, even strokes.

– Go slowly, and watch carefully to make sure the cut is staying along the cut line. If the cut is wandering, either back up and start again in the right direction, or start the cut from the opposite side.

– When cutting completely through a block of wood, place a scrap piece of wood tightly against the side of the block from which the saw blade will exit. This minimizes the amount of chipping at the saw exit point.

– To cut out a rectangle or square inside a car, drill a hole through the center of the area to be cut out, remove the blade from the coping saw, put the blade through the hole, reattach the blade and make the cuts.

SHAPING

(aka Four-in-One Hand Rasp)

– Make sure the wood block is clamped in place before shaping with a wood rasp or rotary tool.

– A handy tool is a Shoe Rasp (aka Four-in-One Hand Rasp).

– Rasps only cut on the push stroke, so use most of your energy pushing, not pulling.

– To keep the rasp working properly, occasionally remove the sawdust from the rasp teeth. A “File Card” or a wire brush can be used for this job.

– Use a flat rasp to shape flat surfaces and outward-curved surfaces. Use rounded rasps to shape inward-curved surfaces.

SANDING

– Start with rough paper, and then progress to finer paper. A good progression is 60, 120, 220, and 400 grit.

– For sanding smooth, flat surfaces, use a sanding block. This is a tool made to hold a 1/4 sheet of sandpaper. Typically it has a soft surface, which is best for smoothing wood.

– Sand back and forth in the direction of the wood grain. On the end of the car, sand in a circular motion.

– To sand inside a body hole or a small surface, use a piece of sandpaper glued to a small flat object (Popsicle stick, small ruler, etc.).

– To sand inward curved surfaces, use a piece of sandpaper wrapped around a dowel rod (or a piece of broomstick).

CONCLUSION
Using the correct tools and using them properly will improve the look and the precision of your pinewood derby body. Just remember, “Measure twice, and cut once!”

From Pinewood Derby Times Volume 13, Issue 3

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(C)2013, Maximum Velocity, Inc. All rights reserved.

Maximum Velocity Pinewood Derby Car Plans and Supplies