Thursday, August 21, 2014

PINEWOOD DERBY CAR SHOWCASE

Big Wheel - John White

I pushed the design envelope this year; after two years of mulling over an idea this is what I came up with. The two front wheels sit just off the track and are there to keep the car going straight. The center wheel rides down the middle of the track and works the kid's legs. My goal was to make everyone at the race laugh. I wasn't sure what was going to happen: would I qualify, would it make it down the track, run into another car, or just plain fall apart? Well -- mission accomplished! He was just a peddlin'. It wasn't fast by any means, but everyone enjoyed watching it race. And it won "Funniest Car".

Awana Tractor - Doug Kile


I'm a leader with our local Awana program at Valley Community Church in Salinas California. Since Salinas is the "Salad Capital" of the world, you see many of these tractors in the fields around here.

Fast Talker - Frank Tonra

I made this car as the Pace Car for Pack 57 in Toms River. I found the idea for this one online and could not resist making it. Someone else came up with idea but it did not matter, they lined up to see the car and laughed all afternoon. I sent the car to the Districts and got the same result. What a joy to see their faces! It was well, worth the hours of sanding.

From Pinewood Derby Times Volume 8, Issue 3

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Thursday, August 14, 2014

Top Fuel Cars - Direct Drive

(The fifth in a series of articles on cars that "stretch the rules")

Last summer I was searching the web for articles and Blogs relating to pinewood derby racing. Most of what I find is not particularly interesting, but occasionally I come across a real gem.

One of these gems was an article written by Eldon Goates, owner of Synthesis Engineering Services. Eldon decided to use PRO/Engineer design software to design a top-performing, direct-drive pinewood derby car for an outlaw race. After designing and building the car, he wrote an article describing the process for Pro/E magazine. You can find the entire article Here

Although I do not have the sophisticated equipment available to Mr. Goates, I decided to make my own version of the car using a pinewood derby block. I do have a lathe to make a few of the key parts, but otherwise, the car was made with basic shop tools.


Figure 1 - My Direct Drive Car

CAR DESIGN
The basic premise of the car is that a string is wound around the rear axle and is attached to a spool mounted onto a motor. When the motor is turned on, the string is wound onto the spool, causing the rear axle to rotate. The length of the string is set such that it runs out just as the car crosses the finish line. So, if the car was used on a track of a different length, the string would need to be adjusted.

The unique feature of this car design is the axle "transmission". To understand how this works, think of a ten speed bicycle. When in a low gear (more torque, less speed), a smaller front "motor" sprocket (the motor is a pedaling human) and a larger rear "drive" sprocket (attached to the rear wheel) is used. But in a high gear (less torque, more speed), a larger front sprocket and a smaller rear sprocket are used.

Now adapting this concept to the direct drive car, at the starting line a low gear is wanted. This means that a smaller motor sprocket and a larger drive sprocket are needed. The smaller motor sprocket is simple; it is just the empty spool attached to the motor. The larger drive sprocket is accomplished by creating a larger rear axle (the right side of the transmission seen in Figure 4). Conversely, near the finish line, a high gear is desired - a larger motor sprocket and a smaller drive sprocket. This corresponds to the nearly full spool on the motor, and a smaller rear axle (left side of the transmission).

To make this work, the string is first wound around the smaller (left) portion of the transmission. Next, the middle portion is filled, followed by the larger portion. When in motion, these are, of course, unwind in the reverse order. The only trick is to make sure to rotate the rear wheel in reverse when winding. Otherwise the car will go backward!

PARTS
First I needed to collect and/or manufacture the various parts. These included:

- Basic block: This was drilled and milled to hold the parts.

- 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. This switch can be seen in Figure 2.

- Kill Switch: 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, 9V clips and cover: Two standard 9V batteries with 9V clips are located in the bottom of the car, hidden by a cover plate of styrene plastic (see Figure 4).

- Motor: 12 VDC motor, 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.

- Motor Harness: The motor is mounted on a piece of brass, fastened to the block, and held down by a piece of styrene.

- Axles: Front axles are our 4095-Speed Axles. The rear axle (one piece) is a piece of 3/32 steel rod.

- Bearings: Two bearings are attached to the side of the car in the rear (I used small screws to catch the flange of the bearing). Thus, the entire rear assembly (wheels, axle, and axle transmission) rotate as a unit, supported by the bearings.

- Bushings: The axle was a bit loose on the bearings, so I inserted two short pieces of copper tubing between the wheels and the bearings to keep the axle assembly from shifting left or right.

- Wheels: The front wheels are white RS wheels from DerbyWorx. The rear wheels are two inch servo wheels from Pitsco. This larger size was needed so that the string spool would clear the center guide rail (it also helped performance). I had to make bushings of black Delrin so that the 3/32 inch axle rod would press fit into the wheels. You can see one of the bushings in Figure 1.

- String Spool: This piece presses onto the shaft of the motor (Figures 3 and 4). It was machined from Delrin. A hole is drilled through the spool. The string is threaded through the hole, and then tied in place.

- Axle Transmission: This piece was machined from Delrin (see Figure 4). It was then slid onto the rear axle and permanently attached with epoxy. There is a hole drilled into the transmission into which the tip of the string is inserted before winding.

- 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.

- String: I used some strong kite string. It tends to fray, so dental floss, or another type of non-fraying string would be better.


Figure 2 - Front of Car


Figure 3 - Back of Car


Figure 4 - Bottom of Car
Left Photo - String is wound and car is ready to go
Right Photo - At end of run, string is wound around the motor spool

PERFORMANCE
I ran this car on our 32 foot aluminum track, and it was faster than all of my propeller cars (see Pinewood Derby Times Volume 6, Issue 15 - April 18, 2007).

Unfortunately, the car sat a little too high, so it would not go under the timer.

Against a fast gravity-powered car, it wins by nearly two track sections (about 14 feet). Here is a Quick Time Video (.mov extension) of the direct-drive car racing against a fast gravity car.

CONCLUSION
This was a fun and challenging project. Certainly my car is not elegant like Eldon's, but it got a lot of attention at our race in April 2007 - it confounded kids and parents alike. "How does it go so fast?," was a common response.

By the way, if you build a direct drive car based on this design, or a different design, please send me an e-mail with a description and photos.

From Pinewood Derby Times Volume 8, Issue 3

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Thursday, August 07, 2014

PINEWOOD DERBY CAR SHOWCASE

Ski Racer - Tom Bybee

My 8-year-old daughter took skiing lessons this year and was wildly
enthusiastic about the sport. Her first car design was a natural
expression of her new-found passion. She placed second in the siblings
race at our Pack.

NASCAR COT: Caterpillar Toyota - Brent Whitlow

My father and I take pride in creating full-bodied NASCAR style
pinewood derby cars. Since the COT (Car of Tomorrow) made its debut
last year in the Nextel Cup, we have been trying to create a pinewood
derby version. This year we were able to debut our first ever COT at our
local SAPCAR pinewood derby racing event.

Pink Ghost - Brian & Brianna Fenech

This car is my daughter's submission from her April 2008 Awana Grand
Prix race with Adamsville Baptist Church. The paint is a bright pink with
ghost Lemans stripes. The car features an extended wheelbase wedge
design, offset front wheels, and raised right front wheel. We used flat
black under the nose to ensure instant timing light trigger. All the
tungsten weight is located near the rear axle, precisely at 5.0 ounces.
The wheels are race-ready, graphite-coated slicks. The axles were
smoothed and grooved to reduce friction and utilized Krytox oil rather
than graphite lube. The car raced a total of eight class heats. It sped to
1st Place - Top Speed in Class, then Top Speed Overall to beat all
competition, including parents. The car also garnered 2nd place in class
for design. We're looking forward to starting our 2009 Awana Grand Prix
racer. By the way, Brianna was also the reining 2007 Top Speed Overall,
(See Car Showcase in Volume 7 - Issue 9).

From Pinewood Derby Times Volume 8, Issue 2

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Thursday, July 31, 2014

Graphite on the Tread

Graphite on the Tread

Do you put graphite on the tread surface of your wheels? Come on, you can admit it. I started rubbing graphite onto the tread surface about eight years ago. It seemed like a good thing to do, and it made the tires look nice and shiny. But honestly, during this time I didn't know whether it did anything to improve the speed of the car.

So I decided to test whether applying graphite to the tread surface has any effect on speed. While doing this, I also tested the benefit of applying graphite to the inside edge of the wheel (the part of the wheel
that touches the center guide rail).

EXPERIMENT EQUIPMENT
The experiment used the following equipment:

- Extended wheelbase Wedge Body(1), weighing 5 ounces, with the balance point at one inch in front of the rear axle, and a raised front-left wheel.

- Pro-Stock Speed Wheels from DerbyWorx(2) - These official BSA wheels are accurately trued, but are not weight reduced.

- Speed Axles from Maximum Velocity(3), polished with Brasso.

- A 32 foot anodized aluminum Freedom Track with a Judge Timer. For each run the car was staged in the left lane.

EXPERIMENT SET UP
Before mounting on the car, the wheels were thoroughly lubricated with Max-V-Lube(4). To prevent the graphite from getting onto the tread surface or inside edge, the wheels were wrapped in paper (Figure 1).


Figure 1 - Wheel Wrapped in Paper

After lubrication, the paper was removed and the wheels were mounted on the car. The car was then aligned, and given a few break-in runs.

EXPERIMENT PROCEDURE
1. The car was run six times, the high and low runs were removed, and the heats were averaged.

2. Graphite was applied to the tread surface of each wheel. This was done without removing the wheels. To prevent graphite from getting on the inside edge of the wheel, a piece of cardboard was pressed against the inside edge of the wheel.

3. Again, six heats were run, the high and low runs were removed, and the heats were averaged.

4. Without removing the wheels, graphite was applied to the inside edge of each wheel.

5. A final set of six heats were run, the high and low runs were removed, and the heats were averaged.

EXPERIMENT RESULTS
The following chart shows the results of the test. As you can see there was a slight improvement in performance when graphite was added to the tread surface, and then again when it was applied to the inner edge.

Note that the amount of overall improvement is only four thousandths of a second. However, the heat times were very consistent; the standard deviation (amount of deviation of the heat times from the average) is quite small (ranges from 0.0005 to 0.0017). Thus, the improvement, albeit small, cannot be completely attributed to statistical noise.


Figure 2 - Experimental Results

CONCLUSIONS
Although the small improvement could be important in a tight race, lubricating the tread surface and inside edge is an extremely small factor in overall performance. If allowed in your race, I would certainly do it, but you would not suffer a significant performance penalty if you choose to not lubricate the tread.

Another factor to consider is that the anodized aluminum track on which the experiment was run is extremely smooth. It is possible that if the experiment was run on a rougher track, there could be a larger performance improvement. However, rougher tracks do not generally provide consistent heat times. So the standard deviation of the heats would likely be much higher, and any improvement could be buried in the statistical noise.

(1) Part 5622

(2) Part 4080

(3) Part 4095

(4) Part 5104

From Pinewood Derby Times Volume 8, Issue 2

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Thursday, July 24, 2014

PINEWOOD DERBY MEMORY
Proud Grandpa


My grandson, Leo received his first pinewood derby kit in December 2007. His first reaction was, "Grandpapa, let's build it now!" I told him that we needed to do some research and planning before we could build.

His pinewood derby was scheduled for January 12th, 2008. So we had time to do the research and planning. As part of the research, I talked to several cub scout leaders whose sons had won first place. They all provided me with great advice, and even showed me one of their son's cars. They also suggested that I go to your web site and read your newsletters.

So we started building the kit. My grandson did the cutting, sanding and painting. I only drew the template on the block of wood and provided guidance throughout. He helped with polishing the axles and the wheels, and I did the drilling for the weight and axles.

Race time came, and my grandson was pretty excited. When we got to the event, he said to the Cubmaster, "I'm going to win!" He was the only Tiger in the Pack, so he had to race with the Bears and Wolves. They had to race three heats. He won all three heats, taking first place by a foot margin.

Next he had to race in the grand finals. There again, he had to race three heats. The race was very tight, and he ended up in third place overall . He was very excited at taking third, and I was a very proud Grandpa.

Donald J. Judeikis

From Pinewood Derby Times Volume 8, Issue 1

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Wednesday, July 16, 2014

PINEWOOD DERBY CAR SHOWCASE

Camping Tent - Jack Long

Camping Tent was a car I made just for fun for the 2006 pinewood derby. The tent is canvas, the poles are toothpicks, the feet are from a doll, and the fire has a red light bulb that lights up.

Old #25 - Robert Mareches

I wanted to share my car with all the fine young racers. This car is probably 40 years old. My Dad and I made this car together when I was seven or eight years old. We didn't know anything about weights or polished axles. With lots of guidance from Dad, I learned how to use a wood rasp, file, and sandpaper. The big decision was what color to paint it! He did find out that sanding the wheel diameter made it run smoother. I thought that this would be the clincher for me to win the race. Well, our car lost, but I still have fond memories of building a derby car with my Dad. The memory means more to me than winning a race; my trophy is this car. Good luck to all you fine young men in building your trophy racer.

Ghost Rider - David & Davey Sides

My 9 year old son, Davey, is very proud of the car we built. He is very enthusiastic about anything regarding Marvel Superheros and loves this particular character. Next year, he wants to made a "Wolverine" car.

From Pinewood Derby Times Volume 8, Issue 1

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Thursday, July 10, 2014

FEATURE ARTICLE
A Winning Philosophy


I originally published this article in Volume 2, Issue 5 - November 27, 2002. During the past five years, I have continued to be disappointed by the number of parents that take a "Win at all cost" viewpoint. I hope that this article will cause many to rethink their philosophy as it relates to pinewood derby racing.

INTRODUCTION
Not long ago I had a discussion with a dad about an upcoming pinewood derby race. He asked if I sold completed cars. I responded that I didn't offer finished cars. I then went on to ask the following question: "Since the pinewood derby is intended to be a child/parent project, wouldn't buying a completed car go against the basic spirit of the event?" The dad responded something like, "Me and my son have a 'win at all cost' philosophy. So we do whatever is necessary to win." I was a bit disturbed by the comment, and tried to explain to the dad why I held a different philosophy. But I soon realized that there was little room for discussion.

What is my philosophy? Why did I react to the dad's comment? I hope to make this clear in the article today, and in so doing I hope that I leave you with some food for thought. Your philosophy certainly does not need to match my philosophy; however, we all need to make sure that we understand our basic belief in the area of competition and ensure that it is the philosophy that we want to impart to our children.

DO YOUR BEST
When considering life's events, I believe that a person should strive to do their very best. In sports, this means giving a 100 percent physical effort. In educational pursuits this means studying to achieve mastery of a subject. In fact, I believe if a job is worth doing, it is worth doing well. From simple chores to running a business, I strive to do my best.

A "Do Your Best" philosophy has at its core the concept of integrity. Thus, the athlete gives one hundred percent and follows the rules of the sport; the student achieves mastery without cheating; the business-person offers a quality product for a fair price.

Furthermore, there is another aspect to a "Do Your Best" philosophy which is not so black and white. That is the idea of fair play or sportsmanship. One can abide by the rules and yet be ethically delinquent by demonstrating non-sportsmanlike conduct. The athlete may badger the competition with cruel words, use steroids or other questionable means to enhance performance. The student may use fragments of another person's work (easy to do today with the Internet), or study a copy of last year's test from an upperclassman. The business
may make questionable product claims or slam their competition. These activities and others go against the grain of a "Do Your Best" philosophy.

Although it is not specifically stated in all cases, the "Do Your Best" philosophy is clearly in harmony with the philosophy of the major organizations that sponsor pinewood derby races:

Awana Mission Statement - "… challenge and train the youth of the world through Bible-based, Christ-centered programs …" (paraphrased)

BSA mission statement - "… to prepare young people to make ethical and moral choices over their lifetimes by instilling in them the values of the Scout Oath and Law. " (In fact, the Cub Scout motto is "Do your best.")

Royal Ambassadors' Motto - "Ambassadors for Christ"

Royal Rangers Aim and Goals - "… to instruct, challenge and inspire our boys in the areas of Bible doctrine, Christian service, moral conduct, and basic beliefs of our church through interesting activities that boys
enjoy."

YMCA Mission Statement - "… to put Christian principles into practice through programs that build healthy spirit, mind, and body for all."

How does a "Do Your Best" philosophy apply to pinewood derby racing? I believe that in the pinewood derby the child-parent team should strive to do their best. This means that they should have fun building the fastest car possible within the guidelines of the local rules, and within the boundaries of good sportsmanship. To further clarify the "Do Your Best" philosophy, let's take a look at another philosophy.

WIN AT ALL COST
The person who follows a "Win At All Cost" philosophy will do whatever is necessary to win, even if it means stepping into questionable, even unethical behavior. No one doubts that the ethical boundary was crossed when figure skater Nancy Kerrigan was assaulted. So certainly if a pinewood derby participant "accidentally/on-purpose" damaged a competitor's car, the bounds of ethics would be crossed. A parent-judge that favored their child's car would also be viewed as crossing the ethical boundary.

But how about the case where a parent has a craftsman friend build the car while the child is home playing. How about purchasing a pre-built car on eBay? Where is the ethical line crossed?

GUIDELINES
Clearly the purpose of the pinewood derby is both a craft-learning experience and a competition for the child. As such, the parent/child team should strive to do their best in crafting the car, and in making it go fast. To balance all of these aspects of the project can be a bit of a challenge. To help you achieve a balance, I suggest the following guidelines:

1. The parent should make sure that the child is involved to the greatest extent possible in all aspects of the project, while taking into account the child's age and capabilities. Here are some ideas for making sure
that the child stays involved.

a. Help the child select a design that they can build, without the parent having to do the majority of the work.

b. Allow your child to do as much as they physically and safely can accomplish. This will tend to slow things down (an excellent exercise in patience for the parent!).

c. Show your child the proper use of tools.

d. Help your child work through the required steps (no shortcuts) and help them understand why the steps are important.

e. Add strength and/or finesse for those steps that the child cannot do (initial saw cuts, drilling straight, inserting axles, etc).

2. If you choose to use more sophisticated tools, supplies, techniques, keep your child engaged at each step. Help them to understand the purpose for each tool or technique, and let them use the tool whenever possible. If you have access to a machine such as a drill press or lathe, explain why the machine is being used, show your child how to use the machine, and let your child run the machine (assuming that they are at an age where they can do so safely).

3. Give your child the pinewood derby building experience. Buying an "almost guaranteed district championship car" is very easy these days, but it cheats both your child and yourself out of the whole experience.

CONCLUSION
What is your philosophy? Do you hold to a "Do Your Best" philosophy or a "Win At All Cost" philosophy; or maybe you haven't thought about it. If not, I encourage you to consider this question and then ensure that you are imparting to your child a philosophy that will serve them well as they grow and mature.

From Pinewood Derby Times Volume 8, Issue 1

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