Tuesday, April 22, 2014

Best Use of Numbers

Last year was our first ever Pinewood Derby. As a Tiger Scout my son had no idea what it was all about so he did not show much interest in building a car. I just wanted a car that would not end up in last place.

We first looked on the Internet for a simple design that would be easy to make. My son helped draw it out and we worked together as I showed him how to measure and make straight lines. After cutting it out he helped briefly with sanding till he got bored (around 10 seconds).

My son did all the painting as we used house paint for the body. He wanted to make some cool colored wheels so we found some model paint and he proceeded to paint the wheels and axles. After it was all dry the car would not move. So we got some new wheels and axles. He used every number sticker that came in the kit - boy he was so proud of himself. He won the "Best use of Numbers" award.

The funniest part occurred at race day. After being allowed to graphite up one more time the scouts entered one at a time with certificates and cars. My son came in looking like a raccoon as he had wiped his face with hands covered in graphite. Okay, so Dad put a bit too much graphite on the car.

My son really enjoyed cheering for all the other Tiger Cub's cars and munching on the snacks. I was happy as he took 18 out of 48 (he likes to win so he was a bit sad when he did not make the finals). So this year he put his sites on winning; I talked him into just shooting for a top-10 finish.

Jim Shryock

From Pinewood Derby Times Volume 7, Issue 10

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Friday, April 18, 2014


Top Fuel Dragster - James Gravely

This is the product of a man with too much time on his hands. It is
constructed from two official Cub Scout PWD blocks making it 14 inches
long. Add another inch for the swept rear wing and the car tops out at
15 inches long. The wheels and axles are also official BSA parts
although extremely modified. The car weighs in at five ounces and was
built mostly for show although it will run very fast.

Show Cars - Andy Holzer

This year we decided to make copies of the three classic automobiles
we own. Noah built a 1966 AMC Marlin, I built a 1963 Lincoln
Continental and Diane built a 1974 Dodge Sportsman van. There was
trouble getting the van to the 5oz. weight limit so it never did race -
lesson to self, if you are trying to make a vehicle this big you should use
balsa. In the race, the cars ran well. Noah’s car placed second in the
Bears and my car placed 1st in the parent-sibling race.

1957 Masarati 250F - Allen Cripe

My son, who is a Tiger Cub (7 years old), and I have watched racing
together since he was born. This was his first derby. We were watching
the Speed Channel before we started the car, and saw a show on the
1957 Masarati 250F. We decided right then, that was the car.

Since it had been 32 years since I competed, I wasn't sure what the
competition was going to be like. So we decided to make "Best of
Show" our goal, and make learning what the competition was like to
improve the next year the second goal. In the end, he won "Best of
Show", and was in the top sixteen for speed!

The car has four coats of sanding filler, and four coats of base coat
(Italian Red). All of the details were then painted on. Finally, three coats
of Gloss Clear coat were applied.

We hand made the exhaust and headers out of 1/8 inch steel rod, and
buried all of the weight into the car. My son and I put tons of hours
into the car; he and I worked together on all the building. As a result, he
won "Best of Show".

From Pinewood Derby Times Volume 7, Issue 10

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Tuesday, April 15, 2014

Tidbits of Wisdom (Pinewood Derby Number Three)
By Michelle Mitchell

For those of you who may not have a Cub Scout in the family, March was pinewood derby month. This was the third of five derbies for us, and through it all I've gleaned a few tidbits of wisdom.

1. If you give your Cub Scout his car kit expecting the pieces to remain intact until needed, you're insane. In the history of the Derby I don't think one boy has made it through without losing at least one part from his car kit. So be prepared. In our case, Spencer and David have lost the axles from their cars nearly every year - not sure why, it's a mystery to me.

2. In fact, it's not a bad idea to buy a stockpile of extra kits knowing of the inevitability of lost parts. The hard thing about losing, say, an axle, is that I've never found the right sized nail to replace it. They're irreplaceable. It's all some Boy Scouts of America conspiracy that BSA only produces unique one-in-a-million nails for their car axles that, should they be lost, are gone forever.

I know, I've tried.

I've torn Lowe's and Home Depot apart trying to find replacement nails and haven't been successful yet - and that's three years experience talking.

3. Don't assume that over-eager Cub Scouts have enough common sense to know that first you design the body then you put on the wheels. Or even that first you sculpt the body then you paint. You'll need to explain all that - three or four times. Every year. That's where those extra kits come in handy.

4. Graphite. Graphite! GRAPHITE!!! If you don't know what this stuff is, be assured that every other scout at the derby will. Google it. Now.

5. There will always be those scouts whose fathers, instead of using the standard-issue BSA-supplied car kits, will purchase the black market contraband pre-cut kits for their boys to paint, effectively blowing away all the handmade cars in the 'Best Design' category.

This may seem like cheating. But don't worry, that feeling will pass and you too will succumb and wish that you'd just bought Junior a Dragon Car kit. Especially when you're combing the hobby stores hours before the derby for lead weights, decals, or nails to replace lost axles (see number 2).

6. There will always be those scouts whose fathers did the entire project for them. This is fine - it's part of the great Circle of Life and all that, as inevitable as death and lost axles - unless those cars happen to win, then it's not fine and things get ugly. So accept it and get over it because the only thing worse than an angry Hockey Dad is an angry Derby Dad. Not pretty.

7. If you don't have woodworking tools, make friends fast with someone who does, as this will save you hours of frustration with a coping saw. Have you ever tried to cut a Corvette from a chunk of pine with a coping saw, and nothing but your knees to hold it steady? It's Dante's tenth circle of hell, I'm pretty sure.

8. Be assured that whatever car design your Cub Scout chooses, the finished product will no more resemble it than a block of Swiss cheese resembles a Ferrari (the below-pictured 'Raptor Rocket' was the inspiration for more than one derby car, but somehow never really
matched the finished results). But that's okay, your son won't notice; if you helped him he'll think his car is cool anyway.

Trevor Monroe - Emerson, New Jersey - 2006

But, as a side note, it's amazing the design concepts you can come up with for a square block of wood. "How about we make your car into a box of cereal? A piece of bubble gum? A cinder block? Sponge Bob?" If the car can be made without a cut, there's instant appeal. See the picture below of 'The Dominator' with a sleek and elegant domino design for an example.

(Owner unknown)

9. Body work isn't everything, but friction is. If you aren't an expert on sanding axles and wheels, lubricating, and weighting then maybe you ought to think about one of those pre-made kits and hope for the 'Best Design' award.

10. The number one technique for getting through the derby is to suggest to your husband that his son should go to his engineer-uncle and grandpa for help with his car. The mere hint to your husband that he isn't able to produce a good derby car will arouse his competitive spirit enough to ensure the project will never fall on you. I made this mistake/stroke of genius the first year and was quickly rebuked and told that lawyers can produce darn fine derby cars, thank you very much, and don't need no stinkin' help from those engineers.

It's reverse psychology at its finest - you'll thank me for it, I promise.

You can read more of Michelle Mitchell's writings at:

From Pinewood Derby Times Volume 7, Issue 10

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Friday, April 11, 2014


Kevin Harvick Car - Brian & Brianna Fenech

This car was my daughter Brianna's (age 11) first ever submission for
her April 2007 Awana Grand Prix race. The paint/decal scheme is
similar to NASCAR's Kevin Harvick. Kevin was the winner of the 2007
Daytona 500. Brianna proudly wore her matching Kevin Harvick NASCAR t-
shirt for the Awana race. The car features an extended wheelbase and
super wedge design. All the weight is located near the rear axles, the
is 5.0 ounces. The wheels are race ready graphite coated slicks. The
axles were smoothed and grooved to reduce friction and hold additional
graphite lube to endure the race. The car raced a total of 8 Class
races. It sped to 1st Place - Top Speed in Class, then Top Speed
Overall to beat all competition, including parents. The race car also
garnered 2nd place in class for design. We're looking forward to start
building our 2008 Awana Grand Prix racers.

The Beast - Vaughn Lester

My car received its nickname from an uncle who thought the design
would demolish everyone else. This was our first pinewood derby and we
only gained interest by watching "Down and Derby". Anyway, after I
finished watching the movie I got on the Internet and happened to fall
upon your website. I quickly soaked up all the information and
designed my car. I then built a prototype and was happy with the
result. I made a few changes and this is what I came up with. I then
realized that there were still four months till the race and I was
already prepared to build the race car and race. However I had to wait
two months before I received the kit and then I built my car. It took
me a week to finish the sanding and then I started painting. I sprayed
four coats of white two to three times a day for the last week before
the event, until it had twenty plus coats of paint!!! I didn't have
any graphite yet but I needed the wheels on to participate in the test
runs. I was amazed how much better it performed than most of the other
cars (nobody else had lubricant either I am glad to say). Now to fast
forward to race day. Excitement builds as cars start coming and
the race hour draws near. I am participating in the leader's and dad's
race so I have a few stiff competitors. I placed 3rd overall, and I
lost to someone who I had given tips from your site to (my mistake!).

Green Machine - Andrew Lester

This was my son's 2007 car. He was a Wolf and we used some of your
matched wheels, tungsten weights, drilled block, and some tungsten
putty. He ended up 1st in Wolf at the Pack level, 2nd in Wolf at
District Semi Finals, 1st overall at Semi Finals (don't ask how this
works, we can only blame it on less than perfect brackets), and 2nd at
the District Finals.

From Pinewood Derby Times Volume 7, Issue 9

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Maximum Velocity Pinewood Derby Car Plans and Supplies

Tuesday, April 08, 2014

Setting the Gap for Performance

One of the most common questions I am asked is, "How much room should there be between the car body and wheel hub?" My first answer is, "Well, our Pro-Axle Guide, Alignment tool, and the Gap Gauge in our speed kit will set the spacing for you." Then the next question is, "If I don't have those, what should I do?" My response is then, "Try using a credit card. It will set a gap that works."

Of course, these responses beg the original question of, "How much room should there be between the car body and wheel hub?" Or better yet, "What is the optimum gap?" I have heard and read some distinctly different opinions on this topic. Several people have said that they set a fairly wide gap in an attempt to minimize the contact between the wheel hub and car body (and also to simplify making the needed observations when performing alignment using the Shim Method). On the other side, Michael Lastufka's DOE (Design of Experiment) tests showed that best performance is attained with a small gap.

Which is right? I can understand the thought process behind the wider gap; less opportunity for contact. But, I also recognize that a wider gap allows the car more "wander room", thus permitting the car to travel a greater distance during its trip down the track (remember that the shortest distance between two points is a straight line).


So, I decided to set up an experiment to measure performance versus the wheel to the hub gap. One car, one set of wheels, and one set of axles was used throughout the experiment. Outlaw wheels where used to minimize the effect of guide rail and track surface contact. Krytox
100 was used as the lube to minimize break-in and maximize the consistency of the runs.

The following gaps were tested. A set of feeler gauges were used to set the gaps.

- 0.015 (Approximate width of heavy business card)
- 0.025
- 0.035 (Similar to PineCar Alignment Tool, and Pro-Axle Guide)
- 0.045 (Approximate width of a dime (0.049)
- 0.060
- 0.090 (Approximate width of an axle (0.085)
- 0.120 (Approximately 1/8 inch (0.125)

To minimize experimental variance, the axles were inserted, the heads were marked at the 12 o'clock position, and the axles never removed from the car. As each gap setting was made the axle was adjusted and the axle heads were checked to make sure that the mark stayed at the
12 o'clock position.

In order to minimize the effect of lubricant breakdown, the test was limited to five heats per gap setting (total of 35 heats). On the first pass, three heats were run per gap, going from the largest gap to the smallest gap. Then two additional heats were run going from the smallest gap to the largest gap. The high and low runs per gap setting were discarded, and the three remaining runs averaged.


As can be seen in Figure 1, the smaller gaps outperformed the larger gaps. Note that there is no real difference in performance between the three smallest gap settings (the difference is statistical noise).
However, as the gap increases, performance decreases in an almost linear fashion.

Figure 1
Wheel to Car Body Gap Test Results

So what is the bottom line? Clearly the gap setting does affect performance. For best performance, use a small gap setting (such as provided by the available gap tools). If one of these tools is not available, then use a credit card (which is typically 0.030 inches).

From Pinewood Derby Times Volume 7, Issue 9

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Friday, April 04, 2014


Vector - William Jenkins

This car was built for an adult Pinewood Derby to benefit the United
Way. It was based on the Maximum-Velocity Vector with slight
modifications. The derby rules did not allow outlaw wheels and the
wheels could not have the inside lettering removed so this car used
Ultralight Speed Wheels on polished grooved axles. It came in first
place out of fifteen cars entered and never lost a heat.

Stealth - William Jenkins

This car was my second entry in the United Way benefit derby. It was
based on the Maximum-Velocity Stealth This car also used Ultralight
Speed Wheels on polished non-grooved BSA speed axles. The car came in
second place to my other entry.

Oilers - Nathan Paul

This is my son Brenden Paul's car from Pack 954 in Tulsa, OK. This was
his Scout division car that took 5th place on race day. While it
didn't win, the project was a fun one since Brenden painted it to
represent the local CHL hockey team, the Tulsa Oilers. Our family
sponsors one of the players and Brenden was lucky enough to get him to
sign it before race day.

Panthers - Nathan Paul

My son ran this car in the open class for pack 954 in Tulsa, OK. You
can see his love for the NFL theme, and the body design is one that
has served us both well in years past. The car took second place
in the race.

From Pinewood Derby Times Volume 13, Issue 13

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Maximum Velocity Pinewood Derby Car Plans and Supplies

Monday, March 31, 2014


Touchdown - Mark Leedom

This is my son Derek's 2014 entry for Pack 352 (Raleigh, NC). It is
named "Touchdown" and uses your fender kits as well as your tungsten
COG weights. This was the speed winner for the Bear Scouts this year,
and next we move on to the Impeesa District derby!

Police Cruiser - Mark Leedom

This car was in response to your recent article on light bars. I
wanted to share this low-tech solution that we had used last year. We
bought these clip-on lights for the kids from a street vendor at our
local 4th of July parade for $1 each. They weigh 0.2 ounces with the
batteries and flash alternating red/blue. I used a Dremel to cut the
clip off, and just a touch of poster putty to hold it in a hole I had
drilled so that it was somewhat recessed. It didn't win, but it was
definitely a crowd pleaser!

Seriously Blue - Jason

This is our fastest car so far. It was so fast that the parents wanted
a second inspection of the car. After passing yet another inspection,
the races continued. This car took 3 trophies: fastest in age group -
fastest over all - best in show. Thanks to Maximum Velocity and all
the speed tips, the little guy and his Dad went home happy!

Vector - Russell Rau

This year's car came out pretty cool with a carbon fiber-like overlay.
The car set a track record its first race, then broke that the second
race, but then slowed down the rest of the day. It developed a
wobble, not sure why. Anyway, it was just quick enough even with the
wobble to take first.

From Pinewood Derby Times Volume 13, Issue 13

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