As usual, click any photo to bring up a larger version.  

Pinewood Derby Time!

 

Call it what you will: Cub Cars, Pinewood Derby, or Kub Kars. Whichever you choose, every spring it's racing time!

All the cars our family has built over the years.
Yes, you counted right, there are twenty-two.

 

It seems like Pinewood Derby is the more well known name, especially among my US friends. However, the boys club at our church has always referred to this as "kubkars", and so that is what I will do here.

For those people who might not know... racing small wooden kit cars is an annual event at kids clubs all over North America (I have no idea if it extends beyond those borders). Kids are given kits consisting of a block of wood, some wheels, and some axles (nails or screws). They are supposed to work with their parent and make a car. There are size, weight, and material restrictions. The cars are then raced down a wooden track, propelled solely by gravity. If you want to know more, head on over to Wikipedia or Google...

This year's set of cars from our family.
From L-R: Zooming Fish Thing, Minecraft, Popsicle, and Black Triangle Thing.

 

For years, the boys club at our church (cadets), has challenged the girls club (GEMS) to build kubkars, so on race night the hall is packed with screaming kids as well as their parents and grandparents in attendance. Some might call it a battle of the sexes... and at that age, you're right. It's boys against the girls, winner take all.

There are several websites out there devoted to helping you build the fastest car possible. There are companies that will sell you kits, instruction manuals, special weights, and designs "guaranteed" to win. I'm not going to go that far here.

My wife and I have four kids, so over the years that adds up to a lot of cars. This year I gathered them all together to take some photos. That idea grew a bit into this web page, which is partly a photo album of years of racing, along with just a few building tips.

Race Day!

(Faces blurred for privacy reasons)

The track is set up in the atrium. Arrive early if you want a good seat, as this is about to be surrounded by screaming kids.

Our track was built for three cars, however we only race two at a time, as our software (ancient DOS-based) is based on triple-elimination. So we run two cars at a time, and the winner advances, and the loser has two more chances before they're bumped.

Different group use different methods and software. Some events are strictly based on time. Some groups don't even have electronic scoring and just judge the winner by eye. I wouldn't want that job, as there were many close finishes.

Here are most of the 2013 race entrants. This year we had 67 kids enter a car. All the cars were weighed and checked the week before and then locked away until race time. There are a stunning variety of designs.
Two cars are loaded up on the track, ready to race. Each one is balanced against the starting pin.
Under the track is the "trigger", which is connected to the starting pins and also to the tracking computer. (You can just see the grey wire hanging down beside the wooden leg of the track support.)
The trigger is pulled back, and the cars race off.

The next few shots are a bit blurry, my apologies. I was shooting without a flash, as the use of a flash can prematurely set off the electric eyes that are at the finish line.

Racing down the track. Fish thing is pulling ahead of purple Rolls Royce. (My wife designed and built the red fish thing. She is a GEMS counsellor. The purple Rolls belonged to my eldest son, who is a JR Counsellor with the boys club.)
And the finish. On our track we have electric eyes mounted above the finish line -- the black objects with the grey wire coming out of them. These point down, and the first car to break the beam is the winner.

The software also calculates and displays a "miles per hour" of the winning car. I placed that in quotes as I doubt it's accuracy, given that it was posting speeds of 248-260mph!!! Let's just say that each race is only about 2-3 second long.


Five Years of Food:

My daughter is not really into cars, so her cars have always followed a food theme. So here are five years of food. In reverse order, from L-R: Popsicle, Ice Cream Sundae, Pizza, Ice Cream Sandwich, and Watermelon. (complete with real seeds, though not actual watermelon seeds.)

My oldest son, now a Jr Counsellor, has seven years behind him. Not sure how many more ahead. There is no real theme here, just having fun.

And here are the six cars of #2 son. Of particular note, I think, is the one with flames, as well as the one that is itself a race track with cars racing down it.

Now, #3 Son is only in his second year, so I cruelly did not make up a feature photo of his two cars. In the banner at the top, look for The Tank and the Minecraft Man to see his cars.



Just A Little Building Advice:

My first piece of advice is to focus on weight. Our rules allow 142 grams. If you want your car to do well, you have got to have the weight at, or very close to, the maximum allowed weight. However, pine blocks of wood do not weigh very much, and if you start trimming it down to make a slender aerodynamic car, then it's going to weigh even less. We frequently need to add as much as 75grams to our cars, to bring them up to the max weight.
I generally use either a section of steel bar or small fish weights. For the steel bar, measure and cut off the required amount, drill a hole in the body, and epoxy it into place. The way to know how much to cut, is to weight the whole bar and then divide by the length, which gives you pretty accurate measurement of how many grams per inch the bar weighs. Fish weights are small, easy to handle, and can be easily epoxied into a recess drilled into the bottom of the car.
Do NOT forget to allow for the weight of the epoxy and the paint.

In fact, contrary to this photo, I recommend that you paint the car before you finalize the weight. I was surprised at how much weight was added by 2 coats of primer and 3 coats of paint.

Here are a couple of examples of what has NOT worked for me. With the blue and the red car, pictured here, we tried gluing some steel bar on top of the car, but it did not hold. Maybe if I had roughed up the steel a bit more?

The Yellow car in the photo was one of our earliest efforts. I tried putting some round steel ball bearings in those holes, with some hot glue. Not good. They did not stick well at all -- those ball bearings are far too highly polished.

Here are some examples of how to add weight. The two cars pictured on the left have some sections of steel bar glued on top, this time with better epoxy. The dark blue one also has some flat lead weights.

On the right the two cars are shown upside-down. Various sizes and weights of washers are epoxied into holes on the bottom of the car.

Here are a few more. On the left are two cars where I drilled holes lengthwise into the car and inserted some steel bar. On the right are a few other creative ways of incorporating some steel bars into the top of the car. In the front is a LARGE hole excavated in the bottom of the car and filled with fish weights in a bed of epoxy. I actually had to grind at that one afterwards with a dremel-like tool, as it ended up over weight.
One thing to be aware of are notches at the front. You can put a notch at the front, if you like, but you will need to add something like this bit of bent wire shown in the photo. The problem has to do with how the car rests against the starting pin. A notch at the front would allow the car to be forward, which is not fair. So the wire is mandatory.
(Same car shown upside-down.)

The wire is all you need, but what you want is to also add a bit of tape to the wire. You need that to ensure that your car properly trips the electric eye at the finish as soon as the front of the car crosses the line. Without the bit of tape, the eye might miss the wire. (So that is a bit of insurance.)

The next piece of advice is to be very careful when installing the wheels. Crooked wheels will lead to a car that wiggles all over the place on the track, and the friction from rubbing against the track guide will slow you down. This year I simply re-drilled all the axle holes on my drill press, to be sure that they were absolutely perpendicular. Even with that, it is tough to keep the screw perfectly straight when attaching the wheels.


And that pretty much brings us to the end of this photo essay.

 

Thanks for reading!