The Block of Wood – Part 7

The Big Race

With all the build up to the big race, we were hoping to have a respectable showing, knowing that many of the other scouts would have expert assistance for their cars. There were 54 heats with six cars in each, spaced at a dizzying 45 seconds apart. The top cars sped down the track in less than 4 seconds, usually around 3.8 seconds. The slower cars, well they varied somewhere over 4 seconds up to nearly 5. The individual heats consisted of cars entered from all levels, the little kids, through the older webelos, to the parents entered in the open class. Each den was awarded a 1st, 2nd & 3rd place trophy based upon average speed, not by placement in each heat. So the races were an hour of straight activity until the end, when the race system tabulated the results for each group.

I was able to grab some video of Connell & Liam while in the same heat.

As the video indicated, we had a respectable, showing.

Here are our individual times:

Liam

Car Name: The Gray Wolf

  • Avg. Time: 4.0686 Sec. (217.9 MPH)
  • Fastest Time: 4.0290 Sec. (219.1 MPH)
  • Slowest Time: 4.1011 Sec. (215.3 MPH)

Connell

Car Name: The Failed Stripe

  • Avg Time: 4.1073 Sec (215.0 MPH)
  • Fastest Time: 4.0316 (219.0 MPH)
  • Slowest Time: 4.1513 Sec (212.7 MPH)

Ray

Car Name: NFC North Division Champs

  • Avg. Time: 4.3127 Sec. (204.7 MPH)
  • Fastest Time: 4.2190 Sec. (209.3 MPH)
  • Slowest Time: 4.5008 Sec. (196.2 MPH)

The three Hagen boys with our cars and trophies.

At the end of the races, Liam took 3rd in his den, while Connell & I, well we were just ‘participants’ in the open class. (Notice my car was by far the slowest. Some people may say that is like my driving in real life, but we won’t go there right now.)

We’d liked to have been a bit more competitive with the race leaders, but one of the lessons that the Pinewood Derby teaches the boys is sportsmanship and that most of the fun is in the process of building our cars together.

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The Block of Wood – Part 6

Mark Rober, a former NASA engineer, is the source of a very popular YouTube video that explains how to use science to create a fast pinewood derby car.

Mr. Rober very fun video demonstrates the rail rider method that we are attempting to follow again this year.

We’ve polished our axles and waxed our wheels. Now it was time to bend, or cant, our axles.

1 ) Use the axle bending tool.

Using a regular hammer and the axle bending tool, we bent the front right axle (the wheel that will be riding the center rail) approximately 1.5 degrees. It is important to place a mark at the 6 o’clock position on the axle head prior to canting this axle.

6 o’clock mark

The left front axle (the wheel that will not be touching the track) is bent 2.5 degrees. This isn’t an exact measurement, but we’ll trust the tool.

2) Insert the Wheels.

Instead of canting the rear axles, we simply used a special needle nose pliers to insert the axles at an angle. The wheels were inserted to the point where they nearly rub against the car body.

The axle tips protrude up and out of the axle channel.

The front axles were installed using the pliers. The front steering axle was inserted with the mark at 6 o’clock, whereas the opposite axle was turned until wheel does not touch the ground. The steering axle as a bit more lateral play than the rear axles to keep the wheels from fighting one another.

As the video demonstrates, we achieved the desired result of the front wheel angled top out and the rear wheels bottom out.

Front Wheel

Rear Wheels

3) Attaching Weight

We starting using flexible, stick on weight available from any of the retail stores last year. It is super easy and fast to get the car up to weight. Connell’s car was a bit under weight, 1.8 oz even with the wheels!

I took a 2oz weight strip, plus an additional 1.2 oz to get it up to the 5.0 oz maximum weight.

4) Tuning the Wheels

Like the video pointed out, the canted front wheel provides an easy point to tune the car to move in the desired manner. We set up a board in our basement to test the drift (as noted in the video).

We used the pliers to adjust the axles to get the drift to the point where the cars look OK. Graphite is the universal lubricant for pinewood derby cars, but years of getting graphite everywhere showed that the more expensive Krytox oil is well worth the cost. A drop or two on each axle does the trick.

Less than two weeks until the derby. We’ll play around a little bit more, but I think we are ready.

 

 

The Block of Wood, Part 5

So we ran into a bit of roadblock this week. It came time to bend our axles for the desired ‘rail rider’ design. (We’ll get to that later.) In searching through my pinewood derby equipment, my bending tool was no where to be found. I turned the house upside down to no avail. It was gone. I remember lending it to another Cub Scout and parent last year and think I remember getting it back. But nothing after that. Ugh. The search for the bending tool and subsequent search for a replacement got me thinking that this would be a good time to mention where pinewood derby supplies can be purchased in the area.

Michaels – Yes the Michael’s craft store has a decent selection of pinewood derby supplies. 40% and 50% off coupons offered on their website or weekly circular can help you get a good deal on tools. Michaels also sells the $0.89 small bottles of acrylic paint in a full palette of colors, which makes it a must stop for your derby supplies.

The Scout Shop – The Boys Scouts of America Shops around town have a nice selection of specialty tools and supplies. You can even get tungsten weights and Krytox oil here. The prices are actually very comparable with anything you will find online.

Hub Hobby in Richfield has at least twice the selection of any other place in town. The Scout shop or Michaels each carry one line of pinewood derby products, whereas Hub Hobby carries three different lines! No matter if it is decals, pre-cut blocks, specialty tools, glue, lubricant, they have it and at the best prices in town

The Pinewood Derby wall at Hub Hobby

Overall you can purchase everything you need online, but not necessarily at a discount. Hub Hobby’s prices are the lowest and will likely be at a discount from anything you will find online.

The Block of Wood Part 4

After the axles are polished, the wheels require polishing of their own to minimize friction. Again, a multi-step process was used to prep the wheels.

Step 1 – Taking a power drill, a cut-off cotton swab stick (made of paper, not plastic), and a plastic scratch remover we attempted to polish the inside of the wheel bore by eliminating any minor scratches. The process is to dip the stick into the scratch remover and use the drill at a very low speed to spin the stick through the wheel more. The process makes a distinct squeaking sound to let you know that there is enough friction present to polish the wheel bore.

Step 1 – Polish inside the wheel bore.

Next – The wheel is placed into a bath of dish detergent and shook around for about 30 seconds.

Step 2 – Washing the wheels

Once out of the bath we dried off the wheel and blew off the soap suds. Then, using a pipe cleaner to buff up the inside of the wheel bore. Note that we used cotton pipe cleaners and not chenille sticks. Chenille sticks have plastic and fiberglass elements that will scratch the wheel. So yes, these are pipe cleaners bought at a tobacco shop. (BTW- I realized very quickly that I am not the target demo for pipe cleaners once I walked into the shop. 🙂 )

Step 3 – Buffing up the bore.

The buffing should be done gently to ensure that the cotton fibers do not get all over the wheel. We do not have a microscope or any high-tech tools to gauge how clean the wheel bore is at this point, so we eyeball it to see if the inside of the bore is looking smooth.

The final step is to apply a light coat of wax to the wheel bore.

Step 4 – Applying wax

The wax dries over night and we buffed it again the next day with a pipe cleaner to remove any excess and to shine up the bore yet again.

Let dry overnight

Next Steps – Installing the axles and tuning the car.

The Block of Wood Part 3

Connell said last night that “we are in control of our cars this year.” I wasn’t exactly sure what he meant by that, but when pressed he meant that this year, we seem to know what we are doing. This is the sixth year of building cars, so I’m glad we are finally getting the hang of things. 🙂 Our goal this year, like every year is to have fun. We’ll be happy to have a respectable showing and maybe even win a heat or two.

Two years ago our cars were the slowest in the field. I don’t know what I did, but our cars were horrible. I spent the better part of that “off season” learning more about the secrets to a fast pinewood derby car. We showed improvement last year, but still had room for improvement. Last year we took Connell’s car to PWD Racing in Rosemount and learned the speed secrets used by the cars that win the district and council competitions. Connell took first in his den last year and went on to the district competition. Liam and my cars were respectable, but did not place. The challenge is to try to replicate the processes at home in a less than controlled environment.

Friction is the enemy of a fast car. The first step to reducing friction is polishing the axles. The nail-type axles come out of the box with a bur from the manufacturing process that inherently provides friction. To remove the bur, I rigged up fixture to hold a moto-tool and placed the axle in the chuck. We set the moto-tool at the lowest speed and lightly filed the bur off the nail.

Step 1 File off the bur.

The next steps are to use extra fine grit sand paper to sand off any marks on the axle and to polish the axles to an incredible smoothness. We start with 400-grit sandpaper for up to 2 minutes on the axle. Again the speed of the moto-tool should be at a low setting.

Step 2 Using ultra fine sandpaper.

Next, with the tool still running, is to rub the axle with a piece of cloth to clean and to buff up the shine.

Step 3 – Buffing up the shine.

Ok, sounds easy enough right? Well repeat steps 2 and 3, with a progression of 600, 800, 1000, 1500, & 2000-grit sand paper…for each axle!!!!

Sanding the axle for 2 minutes per step is flexible, depending upon the attention span of the operator. I found that 45 seconds to a minute per step is about right to keep my boys engaged. With that said, it’s about a half-hour operation to polish all four axles.

Step 4 is to treat the newly polished axles. We typically press the nail point end of the axles about 1/3 of the way into a piece of styrofoam, I (the adult) spray the axles with the a dry silicone spray. There is a product called “Jig-a-loo” that is ideal, however it is no longer available for sale in the U. S. I settle for using a WD-40 product that dries without a residue.

Next Step – Polishing the Wheels.

The Block of Wood Part 2

After cutting and sanding, we painted the car bodies using inexpensive acrylic paint. The paint comes in many colors and drys quickly. The boys applied as many coats as needed with cheap foam brushes and have a finished product within a few hours.

Liam purchased a decal them kit to give his car a little bit extra pop.

Liam’s Car

Connell and I went for racing stripes, they didn’t turn out as well as we hoped. But we figured they are good enough for the Open Class.

Connell taking off the paint tape to reveal his racing stripe.

Connell’s Car

My Car

I decided to add the racing stripe on my car after the purple base coat, so after 5 coats of yellow paint I had nice a yellow stripe.

After we were confident that we were done painting, it was time to apply the top coat.

Up next polishing the Axles.

The Block of Wood Part 1

The Block(s) of Wood

The annual Cub Scout Pinewood Derby is a big event each January in our house. I spend countless hours each January with both boys building their cars out of a block of wood. Liam is a first year Webelo, meaning that next year will be his (and our) last year building cars.

I usually build a car to race in the “open class” for family members to build a car to compete. (I think we have to allow the Dads to build their own car and not completely build their son’s car.) This is Connell’s first year as a Boy Scout, yet he wants to build a car to compete in open class. I thought it would be fun to chronicle our steps in building our cars this year.

This week we cut the cars to the design on the block of wood, sanded them down, and prepared to paint.

Sanding

Sanding the saw marks off with a palm sander.

Detail sanding with 150 and 220 grit sandpaper.

Ready for painting!