Wednesday, December 21

Our 1st Pinewood Derby Car from A to Z - 童子军松木赛车 之一

Scout Pinewood Derby Car KitMy son and I had zero background about the Pinewood Derby Car when we got his car kit from our Pack. Over the past 2 months, we did lots of homework via Google & YouTube and also bought several tools & accessories for the project. Eventually, we built our first Derby car and surprisingly brought a trophy back home.

CAT Toolbox for Cub Scout Pinewood Derby Car ProjectNow I like to share our lessons/tips learned from this project. I am
not trying to focus on some technical depth about how to make your car faster or more realistic but more to summarize the whole project with a series of steps. It probably does not help or spark those Derby gurus but hopefully gives some hands to the first-time maker and beginners.

One question before I start - does your son have his own toolbox? If not, it is probably a good time to get one for him. I bought a CAT Portable Toolbox for my son. It turned out to be a good decision; especially on the contest day he had everything in one

box for adjusting and tuning.

0. Daddy’s homework

Daddy has to do some homework and online research especially for the first-time Derby builders like my son and me:

  • Clearly understand the contest rules. Each pack may have different rules on weight, add-on accessories, lubricants, polishing, etc.
  • Get an extra Derby car kit just in case if you need a redo. Either buy it from your pack or from amazon.
  • Watch YouTube tips & tricks videosMark Rober's clip is a must-see. Don't just believe everything from the videos, and you got to do some study. 
  • Wooden track or aluminum track? This is critical...check it with your Pack-master. The type of track will determine whether to use rail riding or not.

1. Planning

wrote a simple flowchart listing all the steps; marked which steps would be on his own or with my help; estimated how long each step would takeGreat opportunity to blend some Project Management flavor. Many dads may miss this by rushing into the building phase. Nothing fancy, I just sit with my son and wrote on a piece of paper listing the following steps into a simple flowchart. Moreover, I asked him to mark which steps would be on his own or with my help. Also, asked him to estimate how long each step would take -- make sure it would be done before the due day. In this way, my son not only got a big picture but also planned the project accordingly without missing his other activities such as baseball practice and music lessons.


2. Design

What is your goal - to be fast, realistic, or colorful? Remember your Pack may have different types of awards. The speedy award is the most competitive one, but other may be not. My son won the most colorful award - pretty good for a first-timer. 
One tip is not to draw on the pinewood block directly. We simply copied the front/side/top of the pinewood block on a piece of paper and then use a pencil to draw the front/side/top profile the car on the piece of paper.
As for speed, it is all about weight and lubricant:
    Tungsten Canopy Weight for the Pinewood Derby Car Project
  • Add weights and make sure the total weight center is about 1 inch from the rear axles. I used Tungsten Canopy Weight. It is exactly 2.5 oz with a perfect aerodynamic shape. It is a little pricey but worthwhile. 
  • Polishing wheels to make them lighter and smoother - check your Pack rules, too.
  • Keep the total weight as close as 5 oz. The more weight, the more initial energy, but don't exceed 5 oz limit - it will disqualify your car.
  • Add dry graphite lubricant.


3. Cutting

cut the pinewood Derby car with a coping saw and clamp-on viseNo matter an easy or fancy design, a Coping Saw and a Clamp-On Vise are required. Again for a first-time maker, check these YouTube videos on how to use coping saw. Do some practice before cutting your pinewood block. Tips: coping saw tips should point to the handle and it cuts on the pull stroke.
A Coping Saw for the Pinewood Derby Car Project A Clamp-on vise for the Pinewood Derby Car Project

Dremel 4000-4/34 High Performance Rotary Tool Kit for the Pinewood Derby Car Project

4. Sanding

A power rotary tool is your pal, especially when you did a poor cutting job. I did some online study and decided to go with Dremel 4000 Tool Kit, but either Dremel 4000 or Dremel 3000 should work. Please make sure you son wears a mask and safety goggles while sanding.

paint and touch up the pinewood derby car

5. Painting

This is your son's step. Believe him and offer help only if needed. Let him choose the color and pattern. My son wanted to paint his first Derby with his favorite color - green. I doubled at first, but he insisted. It turned out he was right. On the contest day, his green Derby was so standing-out compared to the other cars painted in standard colors (black, red, sliver, or blue). Eventually, he won the most colorful car award!
Any acrylic paint should be OK, and I used Apple Barrel Set. The other tip is to get some Craftsmart Paint Pens for touching up.

6. Finishing

Finishing the pinewood Derby car with the Minwax polyclinic clear gloss sprayOptional step. The true benefit is to make the paint last longer and likely add a little bit aerodynamic advantage due to less air drag on a smooth surface. We used Minwax Polycrylic Clear Gloss SprayAs show in the picture, the tip is to put the car on two strings wrapping around a shipping box. This setup will give you a better and more uniform gloss coating.

7. Wheel/Axle Polishing?

polishing axles of a pinewood Derby car with Dremel 4000 Tool Kit and Dremel Work StationYes, you need it! Not only it will increase the speed, but also give your son a good opportunity to do the handy craftsman job. I set up Dremel 4000 Tool in a Dremel Work Station. It looked really cool, and my son loved to operate it. Better to get Revell Tuning Set/Speed Kit. It includes 1 wheel tuning mandrel, a tube of graphite powder, and different grit sandpapers. You got to have the mandrel to mount a wheel on the Dremel 4000.  For axle polishing, Dremel Keyless Chuck is needed to mount the axle on the Dremel 4000.
Revell Tuning Set/Speed Kit for the pinewood derby carDremel Work Station for the Pinewood Derby Car ProjectDremel Keyless Chuck for the Pinewood Derby Car Project

8. Rail Riding?

This is the key question you should ask yourself at the first place. The answer is very simple: use rail riding only for aluminum tracks but not for wooden tracksWe learned it in a hard way. We configured our car to a rail riding; unfortunately the race track was made of wood. The rail riding actually slowed the car down due to the excessive friction.


9. Bent Axles?

Pinewood Derby 2.5 Degree Bent BSA polished Axles for the Pinewood Derby Car ProjectMy answer is Yes no matter what type of tracks, because (1) it reduces the wheel-track friction and (2) makes the axle alignment much easier. 2.5-deg bent is the magic angle. You may buy the pre-bent polished axles from amazon. I know they cost a little extra but worth the money. Plus, buying these are much cheaper than buying the Axle bender tool to DIY it.

10. Lubricant

Only dry lubricant graphite powder is permitted - no liquid or oil lubricant. Again, check out those YouTube videos. You can simplify spray graphite powder, or use axles graphite packing. I used the latter, and it worked well. One tip - don't forget to bring your graphite tube to the contest, you will need it.

the most colorful Pinewood Derby Car in his Pack11. Testing

The best way is to run your Derby car on the contest tracks. If not possible, just slide it on the top of a flat smooth surface such as kitchen counter top. For the non-rail-riding configuration, you want your car slide straight. For the rail riding, the car needs to draft ~1 inch to the the side over 4-6 feet. Just simply twist the bent front-axles with pliers to make the alignment as you need.


Hopefully you get some basic ideas and hints from my post.  Good luck everyone and enjoy your daddy-n-son's time - it is priceless! :-)