Tuesday, January 27, 2009

The Pinewood Derby!

So, the Pinewood Derby is one of those "rites of passage" things for most little boys. I think it's different than your typical wait-till-the-last minute school project. Little boys are usually into racing things, and their dads usually are, too. It's no different with my boys and me, so we got started plenty early on Kevin's car. Now, I don't blog about my kids, really, but I did think it would be fun to show off old versus new. See, I still have my original car from when I was a Cub Scout around seven or eight that my Dad and I built. It's pictured here.

One thing to note is that these labels are prototypes for Kevin's car. The 45 on top nor the "Carefree Racing" on the side was there back in the day. You can see two circles on the top where the original number stickers used to be. I have no idea what number I used, but it was the stickers that came with the kit (and the new kits still come with the same basic thing!). But I like them so I'm leaving them. Maybe one day I'll do a full restoration of the old girl, but for now she can sport some new graphics.

Back when my Dad and I built this one, we had the full shop facilities of Brady Distributing in Charlotte at our disposal. Unfortunately they were more of an electronics company than a woodworking company, but they did have a band saw, which was what we used to cut the body. We sort of weighed everything and found we were way under the five ounce limit. But I don't think we had a very accurate small scale, so we were pretty conservative in how much weight we added. Dad got a wood drill bit about the size of a nickel and we put a hole in the bottom. Then we put a stack of nickels in there and used a few flat head wood screws to hold them in. Then for good measure we puttied them smooth. Outside of that we simply sanded some by hand and hit it with some blue spray paint. Then we shoved the axles in, made sure there was some play in them, and put graphite in there to lubricate things.

Off to the races! I remember showing up and feeling a bit dejected when I saw the other cars. Many kids had put a LOT of effort into hand carving and painting their cars. I felt bad I hadn't done the same, but didn't know any better beforehand. Then came the weigh-in. Everyone else was weighing in at things like 4.8, 4.9, 5.0 ounces. I was REALLY worried I'd be over. Then we got our turn at the scale. Three-point-eight! Oh no! I was the lightest car in the bunch. For those that don't know, this is bad for the Pinewood Derby. You see, the cars are powered by gravity. They just coast down a hill. First to the bottom wins! Being at max weight is where you want to be and we weren't even close. Oh well, time to take my beating. We put some more graphite on the axles and put her on the course.

First time down, blam, winner by several lenghts. What? How can this be? I was stunned and amazed. And I remained that way, as my little girl rocketed down the course in first place in every race, eventually winning the entire thing. I'm sure I got a medal or something that's now long gone, but I will never forget the day I won. Apparently our sleak body design and special lubricant and leaving some play in those axles was a great recipe, even if we were under-weight a little.

Fast forward nearly thirty years and I'm helping my son build his car. I've tried to make him do as much of the work as he SAFELY can. That doesn't include running the band saw just yet, but he got a clear understanding of the importance of getting the table on the saw square to the blade. He decided he wanted a basic copy of my winning car since it apparently had pretty good aerodynamics. We also did some work to the axles and wheels on his car to polish them MUCH smoother than they come out of the box for less friction. He got a clear lesson in friction, believe me. As for the body design, we also talked a lot about aerodymanics. I'm not sure much of that stuck, but hopefully some of it did. I let him help use my mini milling machine to drill the axle holes. The slots that come cut in your chunk of "pinewood" aren't square to the wood, really (they're close, but off by a little), and that means your car is going to try to turn ever so slightly on the track, which will result in extra friction and thus lower speeds. So we used the mill to try to get ours perfectly straight. We talked about leaving play between the head of the axle (which is really just a fancy nail!) and wheel and the body of the car, again to help reduce friction. I even helped him wax the side of the car where the wheel will no doubt rub the side a little.

We also did some work with the Dremel tool to "true" the wheels as well as polish their inside edge where they'll rub the track a little. Again, lower friction. We had the advantage of a wood shop with big sanding machines, so we used that to help get the wood smooth. Then Kevin did some hand sanding to get the corners nice and smooth. Oh, and we also used the milling machine to cut the slots for the ballast in the bottom of the car. I bought some lead rod to put in there to get to maximum weight. All the way through we kept weighing our pile of parts on the cooking scale we stole from Mom (and dutifully returned with only minor wear and tear!).

We primed her and then sanded a little more. Then we painted her red, which was Kevin's choice (seems he likes his Dad's red race car better than the blue one...which is fine, red is a better "car color" anyway). We called in a favor from the graphics department at our race shop to cut some silver vinyl to make a racing stripe with. I suggested to Kevin that vinyl would be a lot easier to manage than a two tone paint job and he agreed. Seems I'm not expert painter and neither is he, so we decided not to push our limits in this arena. Besides, we were only a couple days away at this point and a botched paint job might end up having to stay if we messed up. Oh, our graphics department went above and beyond by also providing us with a chrome piece of vinyl for the stripe along with the silver. I thought Kevin would love it, but instead he said he liked the silver better. I suppose he thought it was too much bling. sigh That's my boy, conservative to the last.

Last thing was to get the ballast tweaked to the right amounts and assemble. I did the grinding on the lead since it's kind of toxic and grinders are also a bit dangerous for small fingers, but Kevin helped with the screws to hold it in place. We put the wheels on and used a metal spacer to make sure that not only did we have enough play in the wheels and axle, but we had exactly the same amount all the way around. Then we hit the wheels with the magic graphite, and things got really good from there. She rolls instantly on even the slightest of inclines. Seems even our kitchen bar has a minor tilt to it that isn't supposed to be there and isn't noticeable to the naked eye! But the Pinewood Derby car tells all.

Last trick was the lettering. I had discovered how cool it could be to customize Playmobil toys at Christmas using my Brother P-Touch label printer, so we stole that same idea for his car. We used some white on clear label tape for the "Carefree Racing" on the side and some black on clear for the 45 on top and his name on the back (and Kevin did the typing!). Stands out pretty well, and doesn't weigh much. Anyway, without further ado, here's Kevin's masterpiece. May she race well this weekend.


Unknown said...

I think one reason your childhood car may have had an advantage is because the weight was in the back. The farther back the CG is, the higher it starts and the more slope it sees before the track levels out.

Just make sure it's not too far back- our track when I was a kid had an abrupt transition from slope to flat, and one year when we pushed the CG too much the car did a wheelie when it hit the flat and went off the guide...

Best of luck this year!

Donnie Barnes said...

I dunno. I think most kids back then must not have known the graphite trick, actually. My car is roughly 6.75" long and the CoG measures 3.75" from the front nose. So while the weight is in the back a little, it isn't by much.

Kevin's car is currently about 1/8" longer, but the CoG is about 3.7" from the front. That said, the slots are long enough I can move the weight back another quarter inch. Which I suppose I should do.

Currently as it sits (weight fully FORWARD in the slots), Kevin's car weighs 1.8 ounces on the front and 3.1 ounces on the rear. My old car shows 1.4 ounces on the front and 2.3 on the rear. *shrug*

Unknown said...

It sounds like Kevin's car has a good setup. My dad did all the things you did except for polishing the insides of the wheels (good idea btw!) but we still didn't win all the time. There must have been variations in the track lanes, is all we could figure.

Good luck!

Lima Bean said...

Great post. I'm sure Jeff is looking forward to the day he will get to do this with James. It just seems to be a boy thing because if I had to do it with him I think I'd hire out the job.