Pinewood Derby cars - GRM style

I figured people on this board would be able to give a wealth of info on this.

My 7 year old son joined the Boy Scouts this fall. He's very excited to build his Pinewood Derby car. He just got the "kit". I'm completely new to all this, having never been exposed to the boy scouts before (to say I'm not enjoying it is an understatement...but he likes it and that's all that matters). I did a quick web search and found several websites that sell all kinds of stuff, from wheels to axles etc...but I was more looking for helpful hints. Here's where I need the help.

I have very little carpentry skills. Woodworking has never interested me, so I haven't done much. I also don't want to spend much (if any) money on it. That's not meant to sound negative. I want to have a good time with my son, and I want him to enjoy it. But I don't feel the need, or desire, to go overboard. I realize we won't win the race, but that's OK. If he puts his best effort into it and has fun, I'm happy.

So with that in mind, any GRM tips on building this thing simply, inexpensive (i.e. as close to free as possible), but still fun?

When I was a kid, the kit consisted of a block of wood, four hard plastic wheels and 4 nails (axles).

Some kids did nothing more than paint the block of wood and nail the wheels to it. They had fun.

Reducing friction (alignment and lubrication) and maximum weight are critical - aerodynamics comes in third.

Why not go with a theme, a la LeMons? What about a Dakar truck? Keep the woodworking simple and focus on creativity.

He needs to win this thing.

Don't lay a tool onto that block of wood until everyone here has kicked in every bit of knowledge that they have, assess the data and then get to work. This will be the fastest, cheapest block of wood in the history of scouting.

Edit:

Here's my car, circa fourth grade. The brown car love goes way back for me. As I recall, it took second place in both the downhill and the concours. You'd think that it would have put me in a strong position for an overall victory, but, alas, they were separate events and the scores were not combined. The drag race was rained out that year.

The design of the car was nothing special, but the key was underneath. I drilled out the underside of the car, filled it with melted lead and then drilled out the lead until it was right at the maximum weight.

Before you jump to any conclusions about fatherly help, note that I did all the work myself. Forget about the fear of lead paint on the windows, I spent a lot of time working with lead when I was a kid. My grandfather had a rubber stamp business and the type sets were cast out of molten lead. Big bars of lead were a constant presence in my childhood. Which may explain a lot about me. Or, maybe not. I'm not really sure because I have a hard time concentrating.

Of course, if you tried to bring the slightest trace of lead anywhere near a group of Cub Scouts these days, you would be arrested before the HazMat team had time to don their Tyvek suits.

Speaking of Pinewood derby cars...who says they have to be for Cub Scouts?

http://blog.makezine.com/archive/2012/01/steve-lodefinks-pinewood-derby-racer.html

The block of wood is just that--a block of wood. Have fun with it.

The race is won or lost on the wheels and axles. Be sure to file out the ridges on the underside of the "axle" nailhead. Smooth then polish the shaft, gradually working up to 2000 grit paper. Then find some jeweler's rouge or similar and polish those suckers. Make sure the outer circumference of the wheels is smooth. Apply graphite powder liberally and often and work it in by spinning the wheels. The car will usually be fastest a few runs after you apply the graphite.

Roll your finished car on a smooth flat surface and ensure that it runs in a perfectly straight line. Any tendency to pull left or right will have it rubbing on the track's center strip and cost you time! Aligning the car can be a little tricky. Try rotating the axles one at a time, or switch them around. Trial and error. Don't try bending the axles. If the saw cuts in the bottom of the block aren't exactly square, you're wasting your time. All of the "official" kits I've used have been fine. Most of your time should go into axle prep.

Good luck, but most importantly, have fun!

Edit: Oh, heck! How did I forget about weight? Very important. Get a digital balance and get your car EXACTLY at the maximum 5 ounce weight. Make sure the center of gravity is just about 1" ahead of the rear axle. Don't leave any weight "on the table". Everything else being equal, the heavier car will win.

model rocket engine shoved in the rear?

Remember that your son is supposed to build the car with your help, not the other way around...I see a lot of guys who go nuts building them while their kid just looks on, which misses the whole point.

1. Keep your eye on the prize: Quality time with your kid.

2. Buy a couple of extra kits. Build one for yourself, showing him how to use the tools, and let him do his own with your supervision. BTW, some districts have side events for adults.

3. Read the rules. Then ask about local rules. Some restrict you to only items from BSA sources, some require you to use only the slots for axle positions, etc.

4. The speed is in the axles and wheels. The checkbook racers buy prepped axles, wheels, and bodies online. They often win. My cubs did theirs own, using my little drill press to deburr, spin, and polish the axles. A mandrel is available at the BSA stores and hobby shops to work on the wheels. Do not modify the wheels - it isn't legal. Just remove the flash.

5. The body can be shaped with nothing but sandpaper and elbow grease. A coping saw helps with the big cuts. Power tools are even better, but require adult operation or CLOSE SUPERVISION.

6. Draw side and top views of the block and wheels. Let the kid design his own car. Then simplify it into something he can do.

7. Errant saw and tool marks in the body can be filled. Protect the areas where the wheels rub, and work on good paint.

8. Have fun!

If you get interested and have some time ... Derby Talk

stuart in mn wrote: Remember that your son is supposed to build the car with your help, not the other way around...I see a lot of guys who go nuts building them while their kid just looks on, which misses the whole point.

Yup. I've been reading some Scouting forums lately and it apparently has gotten so bad that one Scout was overheard asking his Dad "which car is mine?"

Oh, and don't forget to watch the movie Down and Derby. It should be mandatory viewing for Scout parents, right after Follow Me, Boys

Strange, I just ended up with a pinewood derby car as an Xmas gift. I was thinking about building it and running it against the local scouts (buddy of mine is a den leader and is in charge of their track) for shens. I've been reading a LOT on it- turns out, most of the real fast cars only have 3 wheels on the track to decrease friction.

If you don't want to do a lot of wood working, but you're okay with painting, why not just paint the block of wood like one of the RedBull rally cargo trucks? You could easily sand down the corners a little and then paint it. Then spend the rest of your time on the axles as mentioned above.

It might not be aero, but will be heavy, easy, and COOL!

mndsm wrote: most of the real fast cars only have 3 wheels on the track to decrease friction.

and are made of bacon!

mndsm wrote: ...most of the real fast cars only have 3 wheels on the track to decrease friction.

That's awesome! nail one front wheel just a tad high, then offset the weight plug that you drill into the bottom to one side just ahead of the rear axel to keep the front on the correct wheel!!!

Of course, it could end up like a Reliant Robin if you're not carefull....

ultraclyde wrote:

mndsm wrote: ...most of the real fast cars only have 3 wheels on the track to decrease friction.

That's awesome! nail one front wheel just a tad high, then offset the weight plug that you drill into the bottom to one side just ahead of the rear axel to keep the front on the correct wheel!!! Of course, it could end up like a Reliant Robin if you're not carefull....

That's exactly what they do. Plus all the axle polishing, etc.

Sadly, I was just looking for my drill so I could leave the sand paper static and just spin the nail..... I could be in the hospital in an hour.

Vinyl wrap?

I love that 3 wheel idea, it's cool.

I agree with what several of you have said. I want this to be about him having fun and building the car, not me building it and him watching.

You guys mentioned axle polishing and sanding, etc... So you just sand/polish the nail?

When I was a kid, I wanted to do a pinewood derby. My dad bought the kit for me, and then proceeded to call up people he knew that were engineers. Within 24 hours, I already had a winning car all specced out. But I didn't really want to win, I just wanted to build it. So it never got built.

CGLockRacer wrote: Speaking of Pinewood derby cars...who says they have to be for Cub Scouts? http://blog.makezine.com/archive/2012/01/steve-lodefinks-pinewood-derby-racer.html

I like the unfinished pics better.

Put me in the "block of wood and four wheels" camp. We used to put graphite on the axles, but that's as close as I ever got to race prep other than making one look like a jellybean. I hand-carved a clumsy rendition of a 911 Cabrio for my really ambitious one. It wasn't that competitive, but I didn't care. It was cool and I still have it.

A racer friend of mine blew me away when he showed me the one built by his son. Now, Russ used to work at Pininfarina so he's got some skills. But he was also a great dad so I know the kids were involved. One son built a 1938 Auto Union, the other built this.

Wow, those are some pretty fancy cars. I'm thinking snub nose school bus shape will work for us...

I don't own a rotary tool of any kind. Would something like this come in handy for smoothing the axles?

http://www.harborfreight.com/power-tools/rotary-tools/80-piece-rotary-tool-kit-97626.html

They do this in church, too. My son did this in RA's, with heats and electronic timers. I was impressed by the setup. It also put the emphasis on the kids and their efforts, not the parents skills.

Keith wrote:

I love the bottle cap fenders on this :-)

I remember I did excactly 1 pinewood derby race in my cub scouting days. I recall doing the whole car myself, mostly by clamping the block of wood to the back of my wagon, and going at it with a hack saw and some files to smooth things out. I did paint it black with some white lettering, but it looks pretty lame compared to the ones posted here. I used the screw-on weights on the bottom of the car. They sat too low and caught up on the track, we ended up having to take them off and tape them to the top of the car just so I could run.

I had more fun doing the CO2 race cars in middle school, I did a pickup truck shaped car, and used some pieces from a 1940 Ford Pickup plastic model kit I had made a few years prior, to add "wood" plank sides to the truck bed, which looked like it was carrying the CO2 rocket. Also did a station wagon themed car one year, with racing stripes of course, and some decals from other model kits. Not the fastest but they sure looked cool.

Does the track flatten out at the end?

If it does you can make a lead/steel spoiler to get the weight as high as possible for maximum potential energy.