Detonator

Detonator

Pinewood Derby Times
Volume 10, Issue 3
November 3, 2010

In this Edition:

- Editor's Notes

- Feature Article - Shop Talk - Making Weight Pockets

- Humor

- Product Showcase - Tungsten Putty

- Car Showcase

- Memory -

- Q&A


Editor's Notes

Reader Feedback
In the Q&A in our last newsletter, a reader asked: "... I understand why we maintained our speed but I can't figure out how those other two cars got ahead of us in the first place ..."

In response to my answer, Matt Bierek wrote: "The usual reason the phenomenon described occurs is when you have rear weight biased cars running with center or front weighted cars on standard curved tracks. The back weighted cars always appear to get a "boost" exiting the curve due to the fact that their back weight is still "falling" while front weighted cars begin to decelerate at that same point. Troop 161 in Philomath, Oregon has a 48 foot track with a regulation BSA curve and run out. The longer run out tracks tend to spread the field at the finish line where the boost effect is far more obvious."

My interpretation of the question was different than Matt's. I took the reader's question to mean "Why do the cars jump ahead out of the gate?" In this case the answer I provided in the newsletter was correct.

But it is possible that the reader meant "Why do cars get ahead at the transition?" In this case, Matt's answer is correct.

So, putting the two answers together we have a more complete answer.


Inventory Clearance Sale
We continue to clear inventory on several items including tools and car plan booklets. Click Here to find our clearance items.

Can We Help?
If we can help you in any way with your pinewood derby project, or if you have any feedback regarding this newsletter, please contact us at: info@maximum-velocity.com


Feature Article

Shop Talk - Making Weight Pockets

Mounting weights on pinewood derby cars can be done in many ways. The easiest way is to screw plates on the bottom of the car. The next simplest is to drill holes into the side, back or bottom of the car, and then insert lead or tungsten into the holes.

Another way to weight a car is with pockets in the bottom of the car. To create a very low-profile car and to focus the weight in one area, tungsten cubes are oftentimes used. These cubes are tightly packed and glued into pockets in the bottom of the car.

Although weight pockets can be made with more sophisticated machinery such as routers and mortising machines, they can also be made with a hand drill and a chisel. Today, I will share some tips to take the pain out of making pockets by hand.

Drilling
Before we start drilling, let's cover some preliminary steps:

  1. To make clean pockets, you must use a Brad Point or Forstner drill bit. These bits create relatively flat-bottomed holes with straight sides, which greatly reduce the amount of chiseling which will be required, and minimizes the risk of damaging the car.

  2. Always make the pockets on the raw block. It is much easier to clamp, drill, and chisel into a block than it is to work on a shaped car. Also, if damage is done, then you can easily start again.

  3. Select a drill bit that is properly sized for the work you are doing. If you are a making pocket to hold one row of 1/4 inch cubes, then a 1/4 inch drill bit is perfect. If you are making a pocket for multiple rows of cubes, then use a larger bit (3/8 or 7/16 inch).

  4. After marking the perimeter of the pocket, clamp the block firmly to a work bench, or place it in a vise. Don't try drilling into a block that is not firmly locked in place.

Now, let's move on to the actual drilling. First we need to establish the depth of the pocket. With a hand drill, the easiest way is to wrap a piece of masking tape around the bit at the pocket depth. Then when drilling, you can stop when the masking tape reaches the wood.


Figure 1 - Masking Tape on Drill Bit (marking 1/4 inch of depth)

Start by drilling one hole at each corner of the pocket, making sure to stop at the masking tape. Then continue drilling holes around the perimeter of the pocket, and the interior of the pocket. The goal is to remove as much wood as possible with the drill bit.


Figure 2 - Drilling Holes

Chiseling
Now let's look at chisels. Similar to selecting a drill bit, select a wood chisel that is appropriately sized. For a 1/4 inch wide pocket, use a 1/4 inch chisel. For larger pockets, a 1/2 inch chisel will work fine. Next, make sure the chisel is very sharp - a dull chisel will lead to a damaged car. Finally, be very careful with a chisel. NEVER, EVER pull a chisel towards you, or push a chisel towards your hand.1 Treat the chisel like a knife and handle it accordingly.

Now with the block still clamped in place, hold the chisel vertically and press it down along the perimeter of the pocket - generally a hammer is not needed. Work around the pocket, squaring out the corners. Then, clean out any remaining wood in the interior of the pocket. Two tricks:

  1. When squaring corners, square along the grain of the wood first, then square across the grain, and,

  2. Cut a small amount of material at a time - taking too much material can result in a damaged block.


Figure 3 - Chiseling

Test fit the weight into the pocket. If it doesn't quite fit, then expand the pocket slightly with the chisel.


Figure 4 - Testing the Pocket

The bottom of the pocket will have tiny holes from the center tip of the drill bit. If the car will be thicker than the depth of these holes, then they can be left alone. But if the car will be just a little thicker than the depth of the pocket, from the bottom of the pocket fill the holes with some wood filler. Allow the filler to dry before slicing the car.

Now that the weight has been accommodated, you can shape and finish your car. Good luck with the race!

1Since Maximum Velocity began over 10 years ago, we have only experienced two significant accidents in our shop. One of the accidents occurred during a workshop for our local race. A father broke a chisel rule (Never push a chisel towards your hand) resulting in a decent sized gash on the palm of his hand.




Humor

A man took his young daughter to the grocery store to help him buy groceries. In addition to the healthy items on his wife's carefully prepared list, the two of them returned home with a package of sugar- filled cookies.

"Why in the world did you buy those?" his wife asked. "You know they aren't good for you!"

"Oh, but don't worry, Honey, these cookies have one-third less calories than usual in them," the husband replied.

The wife looked all over the package but couldn't find any claim to that fact, so she asked, "What makes you think that?"

"We ate about a third of the box on the way home."




Product Showcase

    Tungsten Putty Sale    
$1.50 off

Tungsten Putty is a non-hardening, moldable material made from tungsten powder and a polymer binder. Under normal conditions, it will not harden. It can be easily used for fine-tuning the weight of pinewood derby cars. Simply pinch off a piece of the putty, knead it until it is pliable, and press the putty into a cavity or hole in the car.

Through November 16, 2010, you can purchase one ounce of Tungsten Putty for $1.50 off the regular price. To take advantage of this limited time offer, Click Here.




Car Showcase

Tres Pooches - Bob Richardson

We have a family pinewood derby every year after the Cub Scout derby. This year I won a ribbon for the funniest car. The car also won 2nd in the men's division. Lots of fun!

Luke's Ride - Bob Richardson

Luke's Ride was a fun car to build. It took first place at the Scout- O-Rama race in Santa Maria, California, on February 6th in the bandit class, which was open to adults and kids alike. Luke Skywalker was bought as an action figure and cut in half. The wheels were colored with an orange Sharpie pen. When my wife Carol saw the car, she said,"Where in the world did you find a figure that looks like our son Gene!"

King Boo - Justin Martin

Inspired from the character in the Mario Kart video game from Nintendo, King Boo took 2nd (by a very close margin) in our pack race. My son picked the design and helped sketch it on the block of wood and did most of the base paint work. He was too young to use the tools for the most part, and didn't have the patience that was needed to make the car win just a few races. I didn't have the greatest tools with which to work with, but it was all worth it to see the smile and excitement on his face as he won race after race. The car was the talk of the race.

To get the long nose on the front I had to re-drill the axle holes as far back on the car as possible. The Boo figurine was from a Burger King kid's meal; I epoxied it in, hoping it wouldn't fly off when it hit the stop at the bottom. The aluminum engine and plastic exhaust pipes were from toy cars. Because of the design of the car I could not get the center of gravity as far back as I wanted, but tried by drilling lots of holes and filling them with BB's. If I could do it all over I might tweak a few things, but I can't complain about the results -- plus I got some great memories, pictures, and video.


Share your car with our readers!

Do you have a car you would like to 'show off' to our readers? If so, send us a photo of your car along with a brief description of any special features. Also, please include your full name. If selected, we will include the photo and description in this newsletter.Please e-mail photos to:
info@maximum-velocity.com.

Photos must be sent by e-mail in JPG format (minimum size of 640x480, maximum size of 1280 x 960). Please shoot photos from the front left of the car, similar to the orientation of this car:



Send only one photo per car, unless an additional photo is needed to adequately show a feature. Also, only one car per subscriber per year please. Thanks!



Pinewood Derby Memory

Help! We are out of Pinewood Derby memories, but I am sure that our readers have many memories to share. Please jot down your humorous, unusual, sad, or heart-warming pinewood derby tale and send it to: info@maximum-velocity.com

If your memory is used, you will receive a $10 coupon in May of 2011.

Don't worry about literary polish. We will edit as needed. Also, please read our Submission Policy




Q&A

Can you tell me where I can get clear coat for my cars? It seems like a good solution to get the contact area smooth where the wheels touch the side of the body.

It is best to use the same brand of clear coat as the paint. But if you can't find that brand, you can try Duplicolor clear coat (sold at Autozone, Checker, etc). Just make sure to test the clear coat on a scrap of wood painted with the same paint as your car. There can be incompatibilities between paint and clear coat.

However, if you are just trying to get a hard finish where the wheel will touch the car body, you can coat that area with clear nail polish.

How do you measure the relative speed of a pinewood derby car? I see so many cars claiming that their car went over 200 MPH. How do you figure that out?

The 200 MPH speed is, of course, a scale speed, not an actual speed. To calculate the scale speed, you would measure the distance between the starting pins and the finish line in inches, then convert to miles by multiplying the measurement by 0.00001578 miles/in. Next, convert the heat time to hours by multiplying the time by 0.0002778 hours/sec. Then, divide the distance in miles by the time in hours. This gives you the actual MPH. To convert to scale speed, you measure the length of an actual car and divide it by 7 inches. Generally this results in a number between 25 and 27. Then multiply the actual MPH times the scale factor.

Note that times or speeds cannot be compared from track to track, as times and speeds are dependent on the track length, composition, starting height, and slope angle.

If you have race management software, most of these products will calculate the scale speed. In Grand Prix Race Manager, for example, you configure the software with the track length and the vehicle scale -- the software does the rest.


Do You Have Questions that Need Answers?
Do you have a pinewood derby-related question? If so, send your question to: info@maximum-velocity.com. We answer all questions by e-mail, but not every question will appear in the Q&A section of the newsletter.



Back Issues

Are you a new subscriber, or have you missed some of the previous newsletters? Don't miss out! All of the issues for Volume 5 through Volume 10 are posted on our web site and can be found using our Newsletter Index.

Issues from Volumes 1 to 4 are available in four formatted documents, ready for immediate download. To find out more, Click Here.





Newsletter Contributions

We welcome your contributions! If you would like to contribute an article, a web site review, or a speed tip, please send it to: info@maximum-velocity.com.

Please read our submission policy.




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The Pinewood Derby Times is a free e-newsletter focused on the Pinewood Derby. It is published bi-weekly from October through April.

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Randy Davis, Editor, Pinewood Derby Times
E-Mail: info@maximum-velocity.com


Copyright ©2010, Randy Davis. All rights reserved. Please do not reprint or place this newsletter on your web site without explicit permission. However, if you like this newsletter we grant permission, and encourage you to e-mail it to a friend.

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