pinewood derby

It's still there. American Grease Stick (AGS) Part No. MZ-2

FYAAA - for your amazement and amusement -

1. The car weight shall not exceed 5.0 ounces. The official race scale shall be considered final.
2. The overall length of the car shall not exceed 7 inches.
3. The overall width of the car shall not exceed 2 ¾ inches.
4. The car must have 1 ¾" clearance between the wheels.
5. The car must have 3/8" clearance underneath the body.
6. The wood provided in the kit must be used. The block may be shaped any way that is desired.
7. The wheels supplied with the kit must be used. The wheels may not be cut, drilled, beveled or rounded. You may remove the seam from the wheels.
8. The axles supplied with the kit must be used. They may be polished or lubricated.
9. Wheel bearings, washers or bushings are prohibited.
10. The car must not ride on any type of springs.
11. The car must be freewheeling, with no starting devices.
12. No loose material of any kind, such as lead shot, may be used.

Each car must pass inspection by the official inspection committee before it will be allowed to compete. The Inspection Committee has the responsibility to disqualify those cars that do not meet these specifications.

(end of cite)

WHEN IN DOUBT, RTFM!

We have been getting all manner of advice on the subject of Pinewood Derby cars, some of it totally erroneous.

Individual groups are allowed to have their own ADDITIONAL rules. They may create additional classes for cars that have special characteristics prohibited by the rules, such as modified axles, bearings, modified wheels, wheels different than those provided in the kit, suspension systems ........ anything. But those cars are not considered a part of the actual CSA sanctioned event, and are only for entertainment purposes and bragging rights.

If in doubt, reading the instructions is a good place to start. Googling also works.

Steve

Good advice!! My cars always took first in our Scout pack and went to the regionals but they were built in a high tech engineering lab so I don't really have a clue what was so special about them :-)

I googled "pinewood derby car" and got 56,000 hits. Maybe having your daughter do some internet research with that list as a start would do double duty for her--- We went through a lot of this when our kids were young. Made parts in the machine shops at work, had design meetings on the subject, etc.. One year, when we got to the race, the "official" scale was 'way off so not much mattered. My couple of tips:

-wieght is everything. Consider getting the car close to weight ahead of time but leave a 3/8" diameter hole someplace with a tapped plug so you can add enough buckshot at weigh-in to max the car out.

-The wheels are (at least they used to be) brittle. A friend worked pretty hard with his son, but the boy set the car down on a steel folding chair and it rolled right off and onto the floor. Broke a wheel before the contest ever started.

Pete Stanaitis

---------------------

John Bl> Hi,

There was another Thread on pinewoods a while back, but it may have been on another group. The subject of weighting the wheels was discussed extensively, lots of theory and techniques for getting the weight in the wheels. It doesn't appear to be a violation of the rules. I did this myself sometime in the early 70's. What we did to avoid too much parent take over of the kids project, was to have a parent division so the parents could build their own cars, and spend less time building one for the kid. It worked reasonably well. As to the effectiveness of weighting the wheels; it worked great if the track was long enough. The weighted wheels were slow to start, but in the level part of the track, they would overtake the other cars if the track was long enough. As I recall, we had two different tracks and one was a little longer. We also had a separate competition for the best looking creation. Great fun.

There's a huge variation in the wheels that are delivered.

Buy a few kits and choose the best running one, the most concentric ones.

Then build a car where only three of the wheels actually touch the track. Two rears, and a front.

Jim

The *best* pinewood derby advice I can give other than the suggestiins here:

Lobby for an outlaw/unlimited/parents class to keep the kids race fun!

I think there should be a class for "best cheat" myself.

Dave

More money than time? Check out this auction....

The rules state all four wheels have to support the car.

-Carl

Looks like MSC sells aerosol cans of this stuff. That's what I'll get.

I've never polished anything. What sort of abrasives are appropriate?

That makes sense, but might be hard in practice. You'd need a pretty flat surface and some way of weighing corners to some small fraction of an ounce. Maybe you could get at the same result indirectly by taking some practice runs, seeing if the car runs straight, and adjusting the "suspension" somehow until it does run straight.

John

That idea appeals to my excess of engineering education. I was wondering how to gain a little extra in the distance through which the cg drops. Wouldn't you have to invert the car before setting it on the track so the balls are at the top at the start? And wouldn't you have to size the balls so that they dropped in the tube in the time it takes for the car to run the race?

John

Thanks, that was a good read. In my cub scout days we raced balsa wood rockets that were suspended from a long horizontal wire and were powered by rubber band driven propellers. The rules stipulated one rubber band, and the racer had to build the thing himself. A lot of perfectly built rockets with a lot more rubber bands showed up and I finished dead last. It's fun to think about all the things one could do to make a pinewood derby car go fast, but my daughter and I are racing against my friends and their daughters. I don't want to be "one of those dads" to them.

John

In article , tomcas wrote: : :I just got finished helping my son do his Boy Scouts pinewood derby car. : From helping other dads over the years I can tell you that the previous :posts were right on the money. If you can, true the wheels. I pushed the :wheel on a .099 gage pin and took very light skim cuts in the Hardinge :to true the OD to the center hole. There are ridges on the nails from :the cold heading process on both the diameter and most importantly under :the head (like a parting line). I skim cut these off with a thin bit in :the Hardinge to clean up the ridges and parting line and then polished :the OD of the nails where the wheels will contact. I don't use the saw :slots for the nails. Instead I predrill .078 diameter holes for the :nails in the Bridgeport to insure absolute perfect alignment. Do drill :up to high or the car won't clear the 1/4" high track guide. The best :lube is spray on Teflon. Do the nails and wheels but tape the ends of :the nails so they won?t slip out of the car when you drive them in. :Lastly, add enough weight (anywhere) so you are right at the limit. For :the Boy Scouts that?s 5 ounces.

Add any weight near the back of the car so that the added weight starts off higher on the ramp and gives a longer push. Shape the front of the car so that it contacts the starting barrier as high up as possible (a reverse wedge). The barrier rotates down to release the cars, so the car with the highest contact point gets released first.

Furniture wax (Pledge(R), or similar) makes an excellent lubricant for the wheels -- much better than Teflon(R). The Teflon would hold up longer, but how many miles do you expect this thing to go?

Thanks for these references. I had googled but not seen these. The goaskgrandpa site is technically intriguing. His argument seems to be that a significant amount of energy is absorbed by the car bouncing around. He's essentially made a 4 wheel independently sprung suspension so that as little as possible of the car vibrates and absorbs energy when it hits a bump. I've never seen these cars race, so I hadn't realized they bounce so much.

John

This is the part that appeals to my daughter the most. I've always wanted to do metal casting, and she likes to sculpt in clay, so we're going to see if we can't make the ballast weight an interesting shape. I'm inclined to get a piece of the low melting point fixturing metal, melt it in hot water and pour it into a silicone rubber mold we make from her sculpture.

John

That may well be a local rule, the kit that my co-worker and his kid just finished did not state that.

What do folks do to adhere to that, if they didn't have a surface plate to set their car up with?

All you need to do is get a few thou under one wheel. Honestly it's nearly impossible to get them all turning, on a surface plate. We tried.

Jim

Most decent hobby shops have Woodland Scenics Pine Car parts.

They have several different shaped weights with snap off parts to just screw to the bottom of the pine car.

Some places have a 5 Oz weight limit.

Whatever the limit is you want the car just under the limit.

Hugh

Where's the fun in that? My son got to see first hand (so to speak) what some of the inside of my hand looked like. He got to see fat and connective tissue. Now that's instructive! ERS

Just a heads up. Most of the aerosol PTFE's (at least the ones that I've used) have a solvent to dilute them. This solvent has been known to melt plastic. I've personally seen the results on a wheel and it's not pretty.

Fine emory cloth and finish with crocus cloth (if you can find it).

Wayne Cook Shamrock, TX