pinewood derby

[jgoral76 14]

My 6yr old is in a derby race and I need ideas and if possible designs so i can cut it, any ideas

[seymore 90]

I found this link it might help?

How to Build a Car

[R L S 14]

The best one I made (that I remember) looked kinda like a cheese wedge. If you do this design or any design with a real thin nose watch your weight placment as to much weight in the back will cause the nose to lift up going down the track and flip. Dont forget graphite powder on the axles. When you put the weights on we used to melt fishing sinker lead and pour it into a carved out hollow in the car bottom, it stayed put as opposed to the sticky weights they come with, which fall off.

If I remember any more I'll post.

GOOD LUCK!!!

[JFife 14]

I'd PM Doolittle and try and get him to post to this thread......seems like the kind of thing he'd have lots of knowledge about,

[PLD 14]

Yep. My last entry was a red '34 ford complete with chopped roof and fenders. All from one piece of wood per boy scout rules. Not very fast, but it looked GOOD. Being fast is a WHOLE lot of trial and error. What works for one car does not for another. That said, here's the $0.05 tour.

Weight: Big factor. The more weight toward the rear, the farther gravity is pushing, the faster your ultimate speed. BUT, at some point to little weigh on the front causes tracking problems and you lose speed as you zig zag down track. Best seems to place the CG at about 1/3 from from the rear of the car.

Wheels: Deburr, polish, smooth, true, balance, as permitted by the rules. If you can, get 12-20 wheels and take the best 4 that are nearly alike in weight. In many leagues, you can roll on three wheels as long as 4 are installed. Raise one ever so slightly off the floor to reduce friction.

Axles: Get solid axles if allowed. Get jewlers rouge and polish the axles to a high gloss. Remove all burrs. Keep axles and wheels smothered in graphite. DO NOT use the factory holes, get a long bit and a drill press and drill 2 true, parallel axle holes. Your axles are true if your car rolls straight forward and backward.

Lead: Yes, the stick on's suck but don't pour hot lead. It's too dangerous for the benefit. Drill holes and fill with a birdshot (lead) and epoxy (or silicone caulk) mixture. But, if you are a real engineer/machinist: Make a lead rod and drill a hole along the center of the body. Insert lead and attach so it can be dialed forward and backwards to adjust CG on the fly.

and last...

build a home track and test, test, test. Time it, make changes, time again. +time = use old way. -time = keep change. Repeat ad nausem in an effort to shave one more 1/100 of a second.

[PLD 14]

Oh, and one more thing. As you get obsessed with the cars, stop and make sure your kid didn't stop having fun. It's all too easy to do when dads take up a sport they haven't done since they were 13....

[Scott Stone 604]

Which is counter to every car I built with my somes. They were ungly, but boy, were they slow.

A tradition fo rour family, if you finish at the bottom, you get teh DQ award. (Dairy Queen)

[bigchaz 157]

Have to be careful with cheese wedge design in some contests. I remember hearing they will do a run forward and backward to make even the playing field.

[RyanH 14]

Model it after the car in iRobot or Minority Report...both looked very sleek going either direction, upside down, and sidwways :)

Funny you bring this up...a coworker and I were discussing the "best PD car" and ways we could build the absolute car. We use 3D modeling software dailiy, so we could do it in that and calculate the center of gravity. We couple that with the moment of inertia for the wheels and axles and get the best balance out of those guys. THEN we could stick the model into our air flow analysis program (virtual wind tunnel) and see where we could shave corners or add spoilers to make use of directed air pressure. Of course, after 30 minutes of passionate discussion and diagrams, we looked at each other and realized what a bunch of dorks we are and that the ultimate purpose is to have fun and spend some bonding time with our kids. Of course, if I teach HIM to use the programs and methods........

[crispy crittr 14]

I was at a Pinewood Derby Saturday that had over 300 cars entered. I took my camera in, but with the crowd I was not able to get any pictures of the cars. There were a lot of really cool looking cars.

There was a "graphite pit" and next the the scales was a cordless drill with a big bit on it. The drill was in constant use as the cars were being checked in. The sticky weights that were available seemed to go untouched.

I don't know how your son's derby will be set up, but this one was efficient. The six names of the kids in each heat were projected on a screen and the results of the heat were projected on the screen virtually immediately, with times. There might have been two minutes between the heats. Constant action, which is good when you have 300 kids in a gym.

It was a lot different from when I was a kid with two lane tracks.

[RyanH 14]

Someone should host an ipewood derby.

[Rick Arrese 14]

My youngest boy is 7 and he had his first derby last saturday with his cub scout pack. He had a blast. Came home with a "Best Classic" award.

[The Rob 14]

We had our derby 2 weeks ago. The design of the cars did not seem to make much difference in the outcome of the race. My son had an extended cab pickup that we ran down backwards on the track. He took 1st place with the truck. I did take the axles and put them in a drill, and then used super fine sandpaper polished the axles. There is a little axle like deal that you can buy to put the wheels in and polish them also, which is a good idea. Remember that according to official rules the car can weigh no more than 5 ozs. The scout shop has flat weights you can buy that screw on, and then all you have to do is break little sections off to make it weigh right. To fine tune the weight, we use little screws to finish it. I think that you have to use the slots in the block of wood, but you are allowed to true them up with a saw. I made one for myself that looked like a bathtub and put it in the open race. It done decent, but did not win. Just remember to have fun with your son, that is what it is all about!