Pinewood Derby Diagnosis

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My son competed in his second Pinewood Derby a couple of weeks ago. Last year he finished dead last. This year he finished 3rd from dead last. I would like to ask for some diagnostic help from more experienced Pinewood Derby racers. Last year and this year I read a good bit of the material available on the Web and I thought we paid attention to all of the important factors. Based on the behavior of his car on the track in both years, I suspect that we had a weight location problem.
Last year his car would begin down the track with the other cars in a tight group or even a bit ahead. As the car hit the straight away it would slow down significantly as the other cars shot away. Each Scout runs 4 races (1 on each track) and every race was the same. The outcome was the same this year, except that 2 other cars happened to be a bit slower.
Does this sound like an issue of weight placement? Is this what the car would do if there was too much weight towards the back of the car?
The material on the Web seems to be contradictory. The average advice seems to be to place as much of the weight as possible towards the back. One web site qualified this by saying that you should not put the additional weight any further back than the rear axle. The Pack information recommended weight centered around 1/2" to 1 " towards the rear from the midpoint between the axles. Another web site recommended the weight be centered 1/2 to 2/3 back towards the rear axle.
Last year I had read some old advice that was apparently applicable to the old S tracks and we had placed a lot of weight in the back. This year we tried to avoid that. We used a 2 oz bar weight countersunk between the axles. We also drilled holes on each side about 1/2 inch forward of the rear axle to add more weight. Since we were still short, we drilled 3 holes in the back and added more weight there. We ended up weighing in at 141.74 grams. I am afraid that the extra weight in the back tipped the center of gravity too far back, but I just do not know for sure.
We would appreciate any help or advice.
Thanks.
Jim
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"Jim" wrote in message

My advice on the entire "Pinewood Derby" issue:
Buy the cars in bulk, factory made and shipped to the scout hut under armed guard so no parent could figure out how to get an edge; let each cub pick out his racer, blindfolded ...then go straight to the starting line.
Thrill in victory, and participation, no agony in defeat ... and a good time was had by all.
--
www.e-woodshop.net
Last update: 1/06/07
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Swingman wrote:

Amen. I remember in the early 60s when The Derby was big... really big. And SUPPOSED to be a an event between scouts. Sure, a little help from Dad, but just guidance. We all built our cars and had a great time looking at each other's work... you remember... the left over decals from models stuck on the sides, chunks knocked out of the wood bodies from using your boy scout knife too aggressively, paint where it shouldn't be...
Then the Dads took over. The cars looked great, no more airplane decals on your car - just car decals, there were paint >schemes<, not just painted cars, and the nails that were the axles were replaced with piano wire. A glued on washer or fishing weight was replaced by a precise hole filled with molten lead. Eventually it It got so bad that even the Dads thought it was ridiculous, so instead of backing off....
THEY FORMED THEIR OWN COMPETITION!
And those sorry asses (mine included) ran their competitions on the same night at the same meeting as ours. They had their own categories inside the event (best design, best paint, most original) and they even had a huge trophy for the race winner. Eventually there was so much to the Dad's portion of the derby that all but a couple of us quit making cars and let them have it.
I know there were a lot of guys that have similar experiences as I have been in many, many houses over the years that proudly display "their son's" *wink*wink* car right next to their Dad's. When I have seen only one car in the display case, I know of no 10 - 12 year old that could have done the things I have seen.
I know many feel your kids would be scarred forever for losing, so you feel like you have to participate to make the cars as good as you can. But I don't really think it has been about the kids for a few decades. This is not a jab at Locutus, but reading his post, what did his son do to participate? What was his part? He isn't even mentioned in the whole process (except to select paint) again until the end where ownership of the car makes him the winner.
So I like Swingman's idea a lot. Give them a box of stickers to personalize the cars and let 'em have at it. I think the kiddos are a lot more resilient than they get credit for. If they had 30 minutes to customize a car before running the race and that represented the prep part of the competition, I think all would be fine, win or lose. And then they could enjoy the racing with their friends, admiring each other's cars, and eating hot dogs and pizza.
Robert
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On 22 Jan 2007 15:16:38 -0800, snipped-for-privacy@aol.com wrote:

It's a funny thing, but there was a time in the US when kids were allowed to lose, all on their own. Those losers won two world wars, put a man on the Moon, invented the atomic bomb, and did numerous other things including creating an economy so powerful that the rest of the world looked on in awe and terror as its products dominated their cultures.
Since then, what have the "winners" done? Near as I can tell they mostly quit the first time things didn't go their way.
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On 22 Jan 2007 15:16:38 -0800, snipped-for-privacy@aol.com wrote:

Agreed, and I'll add this- it deviates from the pinewood derby a little, but not as much as a guy might think.
We have to stop insulating people from failure. Too many people never learn because they're sheltered until they're too old, and then the first time it happens when they hit the real world, they crack like an egg. I know a whole lot of people who are unwilling to risk *anything* because they might fail- I would hope that the scouts would have an interest in helping those kids involved learn to "Be Prepared" for the inevitable disappointments they're bound to encounter from time to time, and it would seem that a wooden car race would be a fine way to do that in a controlled setting. It's not the Special Olympics, after all. Let those kids make their own pineywood jalopies- if they win, they might want to keep at the woodworking. If they lose, it's a good opportunity to pick themselves up and dust off- they can try again next year.

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BRAVO!!!!
--

"Anybody can have more birthdays; but it takes
balls to get old!"
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Jim wrote:

I am puzzled also about weight placement. I have 2 sons who were in the derby race yesterday. This year we put the cg about 1 inch forward of rear axle. Last year 1 inch aft of front axle. No difference in number of races won or speed noticable between years. This year we polished the axles on one and not the other and treated the wheels the same yet on the heat where they raced against each other they tied, twice since the first time they could not tell a winner but on the second race the third car won. One car won 4 out of 9 and the other (with polished axles I might add) won 1 out of 9 races. I tend to think it is pure luck but there are 3 families whose kids always place in the top 5 or 6 out of 35 or so every year. They claim they do not do anything excessive except make sure the car runs straight. We are friends so I believe them.

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There is some luck, no doubt. Your friends are right. Making the car run straight is critical. I'm not one of the big experts, but we've finished in the top 3 (different kids) 4 out of 7 times.. Of course, we've also failed to get out of the first round in other years, as our pack is very competitive.
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A rock will go down a slope with not too much persuasion. I would think that your wheels are the problem.
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I have story about last years pinewood derby.....
My 8 year old son bought the kit, and I totally forgot about. He wakes me up at 8am on a saturday morning, saying "Dad, the derby is today, we forgot to make my car"... great, we have to be there at 11am.
Most of my tools are over at a house I am rehabbing, about 30 minutes away. Just going over there would take up at least an hour. So I see what I have on hand. I have a cordless drill, a hammer, some nuts, washers and bolts, a jig saw and a dremel tool, and some old red door paint and some brown spray paint in the shed.
My son says Yugioh uses red and brown colors, and he has some yugioh stickers. Ok, that solves that. I go ahead and draw a rough futuristic car shape on the block of wood and cut it out with the jig saw, sand it down and shape it further with the dremel tool and a sanding wheel.
Of course I have no scale at the house capable of measuring the weight of the car in oz, so I have to devise someway to easily change the weight, so I drill in hole in the "back window" and screw in a bolt with about 10 washers on it.
I paint the car red with the door paint, and then do a faded two tone with the brown spray paint. Boy was it ugly, but my kid thought it was pretty cool. I had my son stand there with a hair dryer on it until it was dry (enough) and he added his stickers, then I attached the wheels.
We get there just in time, I proceed to weight in the car, it's weigh overweight, easy enough, brought a wrench with me and removed some washers. After getting the weight just right, I used some graphite on the wheels.
There were about 70 cars competing, my son won 1st place. I don't think I have ever seen him so happy. I was the hero for at least one day. :)
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So, are you saying it is mostly luck, or that you are incredibly good? I thought it was mostly luck, until someone won 2 years in a row.
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heh... I don't know, I like to think it's because I am incredibly good. :)
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Locutus wrote:

Luck has very little to do with it when there are several well-tuned cars in the race. Several times I've seen tounaments that lasted all day, with one car that crossed the finish line first every single time it ran. You can't attribute that sort of success to luck.
Having said that . . .every year Fate chooses to smile on some kid who had little or no help. He takes the nails out of the box and pounds them in with a hammer. The heavenly bodies all line up in the proper orientation, and his car does very well, but it still doesn't beat the ones with polished axles and turned wheels. The rest of those kids usually suffer a different fate. I've seen several cars that stopped before they got to the finish line.
I've held work days in my shop with my tools and assistance to try to help some of these boys be more competitive. But they aren't the ones who show up. None of the single mothers or non-technical dads bring their kids. It's the young dads who are sure they know how to build a fast car, they just need the tools to do it.
In the end, somebody has to be last in every competition. I didn't contribute the genes or the tutoring to allow my boy to be good at football, baseball, basketball or soccer. He certainly knows the agony of being last in those areas. But I can show him how to build a fast pinewood car.
DonkeyHody "We should be careful to get out of an experience only the wisdom that is in it - and stop there; lest we be like the cat that sits down on a hot stove-lid. She will never sit down on a hot stove-lid again---and that is well; but also she will never sit down on a cold one anymore." - Mark Twain
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We race on a forty foot Piantedosi wood track, with a starting pin height of about 45", and the slope runs out flat at about 12' on a level line from the pins. The pin to finish line distance is about 35' measured on the track.
We use tungsten weights that come in 3/8" d. cylinders and we drill the car body out, starting on the centerline of the car and running parallel to the centerline for one row on either side of it. The drilled holes have about 1/8" between each and they are drilled to depth with a forstner bit on the drill press.
We insert the weights into the center line of holes and attempt to get the car to five ounces, with one ounce riding on the front axles. We set the weights to be flush with the bottom of the car.
We straighten the axles in a press and hammer the nail head into the press so that it is square to the shaft, and then file off the webbing below the nail head. Then we lightly file the underside of the nail head into a coned shape.
Then we insert the axle into the drill press and polish it with wet-or-dry abrasive, starting at 600 grit and moving through the grits to a finish with 1 micron polishing cloth. We wipe them down with alcohol and put them in a baggie with a powdered graphite/moly lubricant. We treat the underside of the nail head the same as we do the shaft.
We use a jig on the drill press to bring the wheels into round and then treat the tread with the same regimen of abrasives. We cone the bore of the wheels and we polish with the same set of abrasives. We use the same abrasives on the area of the wheel that contacts the underside of the axle. We polish the inside edge of the wheels with the same abrasives and then we take a rag and push graphite/moly into the surfaces of the coned hub, flat face, treads, etc. We use a piece of drill rod and some liquid abrasive to polish the interior of the bore. Then we clean out the wheels with compressed air, then swab with denatured. Then we put the wheels in a baggie that has some graphite/moly in it and shake them up, then let them sit overnight - they come out a cool looking graphite gray and - we hope - the graphite gets into some of the crans and nookies.
We drill holes in the body at the bottoms of the axle slots, so that the axles will go in straight. We load the wheel hubs up with graphite/moly and push the axles through, trying to keep as much lubricant in the bore as we can. We push the axles into the body until the wheel bores are 1/32" away from the body. Then we spin the wheels for a bit using the air compressor to direct a stream of air over the wheel to make it spin.
Then we set the car on a piece of plywood that is eight feet long and set to a five degree slope, being level side to side. We put a dot on the twelve o clock position of the axle head and we turn each axle a quarter turn at a time until the car can run a straight line over eight feet.
We then run the air compressor over each wheel until we think the lube is gone and test the car for straight again. A little more tweaking to make it straight. Then we pack it with lube and we're ready to race.
The boy ran third out of fifty his first year and second last year. Then he went to the Districts and ran third out of 150.
To answer your question - I think that you have a friction problem, or an alignment problem, rather than a weight problem.
I'd pay a lot of attention to the alignment.
Regards,
Tom Watson
tjwatson1ATcomcastDOTnet (real email)
http://home.comcast.net/~tjwatson1 /
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Piantedosi wood track, with a starting pin

Wheel balancing! And Wheel bearings . . . and machined axles. And, synthetic bearing lubricants. Tried a taller gear ratio? ~:o))))) NuWave Dave in Houston
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On Mon, 22 Jan 2007 18:10:52 -0600, "NuWaveDave"

To me, it is the transmission of the concept of craftsmanship.
The same mentality that makes you create a piston fit drawer, a hermetic dovetail joint, a perfect deep gloss lacquer finish - these are all created by the repetition of simple processes, and the truth of success in any of them is - Character.
Going the extra mile. Being unreasoning in your pursuit of excellence. Doing what needs to be done to make it as good as you possibly can.
I don't have my boy stand in front of the drill press for an hour to win this race - I want him to understand what it takes to win his race, whatever that may turn out to be.
I have been somewhat facile about winning the Derby - I am much less so about the lessons that the process teaches.
The goal with my son is never actually to beat anyone else but himself.
Kipling had a great poem about it. I've had my boy memorize it.
Regards,
Tom Watson
tjwatson1ATcomcastDOTnet (real email)
http://home.comcast.net/~tjwatson1 /
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<snip>

Much more appealing message.
When you get to the point where that son is teaching others how to succeed, that's when the old man tears up a bit.
It isn't really about cars, is it?
Patriarch
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On Mon, 22 Jan 2007 21:49:58 -0600, Patriarch

Pat - If you don't mind me turning this discussion over to my betters:
If you can keep your head when all about you Are losing theirs and blaming it on you, If you can trust yourself when all men doubt you But make allowance for their doubting too, If you can wait and not be tired by waiting, Or being lied about, don't deal in lies, Or being hated, don't give way to hating, And yet don't look too good, nor talk too wise: If you can dream--and not make dreams your master, If you can think--and not make thoughts your aim; If you can meet with Triumph and Disaster And treat those two impostors just the same; If you can bear to hear the truth you've spoken Twisted by knaves to make a trap for fools, Or watch the things you gave your life to, broken, And stoop and build 'em up with worn-out tools:
If you can make one heap of all your winnings And risk it all on one turn of pitch-and-toss, And lose, and start again at your beginnings And never breath a word about your loss; If you can force your heart and nerve and sinew To serve your turn long after they are gone, And so hold on when there is nothing in you Except the Will which says to them: "Hold on!"
If you can talk with crowds and keep your virtue, Or walk with kings--nor lose the common touch, If neither foes nor loving friends can hurt you; If all men count with you, but none too much, If you can fill the unforgiving minute With sixty seconds' worth of distance run, Yours is the Earth and everything that's in it, And--which is more--you'll be a Man, my son!
--Rudyard Kipling Regards,
Tom Watson
tjwatson1ATcomcastDOTnet (real email)
http://home.comcast.net/~tjwatson1 /
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wrote:

<< Snipped for brevity >>

Thanks Tom, I hadn't encountered that one before.
Makes me think maybe I should revisit Kipling- I had kind of missed him as a kid, and figured it wasn't much use going back to revisit the same fella who wrote the Jungle Book at this point.
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On Mon, 29 Jan 2007 05:05:51 -0600, Prometheus

Oh, you really want to. While Kipling wrote some books for kids most of his writing was not aimed at that audience, and even his books for kids aren't "kid stuff".
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