Pinewood Derby Diagnosis

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OK gentlemen, (most of you I am sure)
I'm sure this will p.o. someone but it has to be said,
It is really supposed to be about the principles being reinforced by the Scouts, acceptance of those principles and embracing them as one's own ( and subsequently our son's) which is why we / they join scouting. All the rationalizing in the world, and more specifically on this topic, on this site, does not and will not change those principles. Dad's are supposed to supervise, help, or advise. I can't recall power tools ever entering the equation when I was a kid. Very modest hand tools such as a coping saw, sandpaper and a pocket knife is what required utmost supervision, guidance and advice rang in for the science; (friction, w5eight distribution, aero-dynamics) etc.
In a nutshell, it is about the process as well as the end result. The end result should be satisfaction in learning to create, compete, win/lose and to do all of it with dignity. Dads who don't respect that or just don't get it, should just drop the boy off and let another responsible adult LEAD by a PROPER example and justifications and rationalizations be damned.
OK, off of my soap box. I endure my share of OT political crap that shouldn't even be discussed on this site so I felt comfortable chiming in here because there is at least a theoretical block of wood involved... :)
DJ

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snipped-for-privacy@hotmail.com wrote:

Not a damn thing wrong with what you said. In fact, I liked it! I say fire away!
Robert
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Man, why'd you even bother using "we" in this post? Sheesh.
Blame the engineers you refer to in another post ("Hey, they're cheating, so I will, too!")
Rationalize it as a learning experience ("Son, you're going to have to do this for your son some day, so pay attention.")
Rationalize it because you did well. Make excuses all you want, and I know you will.
But if your kid gets kicked out of school for cheating, let's see how well those excuses hold water. Since pinewood derby is nothing like school, he's not being taught cheating is OK, right? Riigghht.
Whether you realize it or not, when you're not around, the kids talk about who did what. (this coming from a former pack leader) Kids being kids, the ones that didn't do well (but did it themselves) will have lots of ammunition for those that had DaddyCo make their car. And they -will- use it. ("Loser, you can't even build a car! Your Dad had to do it for you!" That's a verbatim quote.) They all know. The kids are psyched when they win, until later, usually during the trophy presentation, they get called out. And all those wonderful lessons you think you imparted are washed out by a few choice words from an eight-year old.
The winners learn the wonderful life lesson that hey, I won, so who cares if my dad did it? And please, spare us the tripe about his "involvement" in the process. Eight year boys don't polish axles down to sub-microscopic levels.
But hey, at least yours will know Kipling. At least have it memorized, anyway.
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On 13 Feb 2007 08:29:38 -0800, mcarver snipped-for-privacy@hotmail.com wrote:

I think that what is needed is a Budweiser Ebony Wood Pro Derby with big prizes and free beer, unlimited engineering innovation is allowed, no one under 21 is admitted, and all cars must be made of species that sink in water.
While the adults are all competing for bucks and pissing for distance the kids will be able to get back to being kids, and having fun with their simple cars that float, learning what they can as the aspire to being allowed to build a sinker.
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wrote:

Winning the PineyWood Derby is a simple process, J.
Make your car weigh five ounces and distribute your weight so that one ounce is on the front wheels.
After that it is a game of alignment and friction reduction.
Get your axles square to the body and parallel to each other.
Then it is a game of who spent the most time with the abrasives.
The team with the best sandpaper wins.
My story is true.
In every endeavour that I have been involved with in my life, be it sports or business, or music, or whatever - the person who is willing to go the extra mile beats raw talent nearly every time.
It's a good lesson for kids and it is a good lesson for us old bastards that might have forgot.
Regards,
Tom Watson
tjwatson1ATcomcastDOTnet (real email)
http://home.comcast.net/~tjwatson1 /
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"Tom Watson" wrote in message

Well said ... world was full of great singers who sat on the couch just waiting to be discovered when we got Tiny Tim. ;)
--
www.e-woodshop.net
Last update: 2/07/07
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Just my 2cents as a former Cubmaster for 15 years of scouting and 3 sons. I have seen almost every possible cheat tried and have had to remove a parent from Pack night. I've seen cars that Detroit would have liked to copy and cars that were blocks of wood right out of the box with the wheels pushed on. win. I knew that the dads did most of the work and I tried to insure that at least the boys watched and helped somewhat (paint, sand, stickers etc.).
It is my observed opinion that to win pinewood derby there are three things required. (Luck, Smooth wheels, Aligned wheels)
Luck --- The starter setws the car shight on the track Smooth Wheels ---The wheels are sanded very smooth and the axles are lubed with just enough grafite Aligned Wheels --- The spot that the wheels touch the car body is pararell to the edge of the wheel
It is the same as bobsledding the smoother you go down the track the faster.
Please remember to have the boys root for thier pack mates as well as them selfves.
Ken G Pack 93
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Don't drag me into this, Tom...
--
Regards,
Doug Miller (alphageek at milmac dot com)
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On Feb 14, 9:43 am, snipped-for-privacy@milmac.com (Doug Miller) wrote:

I wondered how long it would take you to read this and respond.
I do think the artillery image is funny, though - in a road runner sorta way.
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Oh, it is. Rather than participate in the firefight, though, I'd prefer to just sit back and watch this one.
--
Regards,
Doug Miller (alphageek at milmac dot com)
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Jim wrote:

First my credentials: My son's cars won first place at the pack level 3 years in a row. One of those years he raced against more than 90 other cars in a double elimination tournament such as you describe. The other two years he raced against probably 40 cars. Perhaps coincidentally, I have an engineering degree.
Assuming your weight is close to the maximum 5 ounces, I think only one thing can cause a car to run that slow - friction at the wheels and axles.
Forget about aerodynamics. The car is going less than 12 miles per hour and aerodynamics plays a small part at that speed. It may make a difference between first and second, but not between first and last.
Forget about fine-tuning weight placement. It may get to be an issue among the fastest 2 or 3 cars, but not among the slowest. You don't want the front end to be so light that it leaves the ground at the track joints. You don't want it so heavy that the car can't steer itself easily. Other than those issues, I don't think it's very important.
Spend your time and energy on wheels and axles. Look closely at the nail that comes in your kit. It has a spur under the head that wants to dig into the plastic wheel and stop it from turning. The part of the axle that the wheel rides on needs to be soooo smooth it shines like a mirror. There are lots of ways to get there. I chucked the axle up in a cordless drill and had my boy run the drill while I applied: 1. A small file to the offending spurs under the head. 2. Narrow strips of sandpaper starting with 300 grit and progressing to 800 grit. 3. Jeweler's rouge applied on a felt wheel spun by a Dremel Tool while the axle was spinning in the drill. We probably spent 30 minutes on each axle. If the axle is a little smaller in diameter where the wheel runs on it, that's a good thing.
Don''t ignore the wheels. The running surface of the wheel needs to be as smooth as a baby's bottom. Chuck the wheel hub in a drill and sand, then polish the plastic. It will take a high gloss if you polish it. Find a way to polish the inside of the hub where it runs on the axle. I found that the shank of a Dremel bit is just the right size, but DON'T spin the bit in the hub, you'll get it out of round. Instead, put a little grinding compound or jeweler's rouge on the shank and spin the wheel on the shank. I used an air blower to spin the wheel at high speed. Wash the wheel with lots of hot water to be sure you get all the abrasives out.
Adjust the tracking by bending axles as needed so that the car rolls straight when pushed across the floor. You don't want the car to scrub of speed by hugging the center rail all the way down the track.
Lube the axles with graphite lubricant.
If you do all those things, I can't promise a win, but you shouldn't be embarassed.
DonkeyHody "Even an old blind hog finds an acorn every now and then."
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All,
Thank you for your replies, especially those with very detailed advice and instruction. The consensus seems to be that we had a friction problem of one sort or another. I tend to think that that may indeed have been the case as we spent no time this year on checking to see if the car was going straight or not. The primary reason for that was that we had nothing but frustration last year in trying to get the car to roll straight across the kitchen floor. The tip about putting it on a slightly angled board is a good one. Both years we did chuck the axles in the Dremel and polished the shaft and the underside of the head with steel wool. We do not have a small file, but I did use a utility knife last year to shave off the burr underneath the head. This year I could not see any burrs underneath the head, so we only applied the steel wool to the shaft and underside of the head. We also sanded the wheels by hand, but no turning by Dremel or otherwise. Apparently we need to do a much more thorough job in this area.
For lubrication both year we used the Dry Lube sold by the Council Shop. It sounds like graphite is a much better solution, if used sparingly.
To those who replied with messages emphasizing the life concepts at issue here, I appreciate your words as well. We certainly are not out to win, but simply to do our best. We do not feel that we have done our best yet. We have neither the time nor money to go overboard on this, but it is much more fun to have a car that at least hangs with the others. To do this day my son will tell you that he had fun in both years, but building the car and participating in and watching the race. He would like to add to that fun by finishing even better. He is fascinated by what aspects we might be able to change or tweak to improve the car for next year. He is ready to start again now! To that end...
I have two practical questions to help us with improving our performance:
1. How can we test our car at home without spending a fortune on our own track? I have access to a scale, but the only affordable test track that I can find is a single lane 30 foot track on eBay. Since we have two very slow cars, it would great to be able to test a new against them. The 8 foot board is an excellent idea. Are there other affordable alternatives?
2. On the subject of bending the axles, this is where our frustration came in last year. We would push the car across the kitchen floor and try to bend the axles by hand to adjust them. However, that was simply pressing them against the wood of the axle groove, so of course they probably did not stay bent. We have the alignment/camber/measuring tool that is sold in the Council Shop and we did make use of it this year. We did have a hard time finding an effective way to straighten the axle slots. A drill press is obviously needed. Nevertheless, how do you bend the axles themselves?
Thanks for all of your help. This is still a fun process for us both and we are looking forward to our next car project.
Jim
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*snip*

*snip*
From what I remember about my two (and only two) pinewood derby races is the track had a raised section that made the actual "track" You could do this with a piece of 1/4" plywood, ripped to a little under the width of the car spacing (or find out what the official width is if they use that style) and with a square and some geometry (maybe) you can lay two tracks on a board to race against each other.
Cut a piece of plywood in half (2' x 8') or quarters (1' x 8') and you can make a longer run. You'll want to support it with 1x4s minimum.
Puckdropper
--
Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm
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I think that "luck" is a big part too. 25 years or so ago, my son and I built ours going by the Dad watches, kid does plan. Got to the race and it was too heavy. Drilled many holes (some clear through), Crazy looking thing took first place in a probably 25 car race. The kids nicknamed it the "Swiss Whiz".
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Jim wrote:

all 64 cars, so first over all for the troop. Way, way, fastest car there. At superderby (top 5 from each pack - 125 cars all) 1st place after 3 heats, 4th heat rubbed the rail, came in 13th overall. Still just over .01 seconds for 4 heats between him & #1 overall. The cars are all fast at regional.
The physics are simple. ALL the energy of the system at the start is potential energy dependent solely on height & mass. You maximize these by building the car as long as allowed (7"), car at the maximum height, with they weight as far back as will maintain stability (cg in front of rear axle, but close to). However, the difference in stored energy is relatively small given the parameters, as long as you're at max length & weight (the change in height of cg is pretty small range).
You said your sons car kept up down the slope. Heading down the slope is the conversion of potential to kinetic energy (height to velocity). If you're losing on the flat run it's all friction. Air friction is negligible. My son's second year we did a football helmut (of wood) on top of main body. Hilarious looking, wobbled, but amazingly came in 8th overall. Last year, much to my chagrin, he made superderby again (trust me, once is enough) - but barely and got womped (took 8 hours to get through, and was obvious this was one of the slower cars). This year his car is an "arrow" - we haven't even assembled yet.
So what causes the difference - reducing friction. Where he (and other top cars) all pull away is in the flat run. Ways to reduce friction, in sort of importance (most to least):
1) trial roll the car, adjusting the axles, until it runs straight. If it rubs against the center guide rail the entire way ain't gonna be fast (of course, if the car isn't set up straight, out of your control).
2) File the burr formed when the nail head is stamped. This will definitely cause friction, and is easy to remove. A further refinement is smoothing/truing the axles to a true round, but minor. The wheels spin on a single area (bottom) of the nail, so as long as that is smooth should be fine.
3) Remove the "nub" off each wheel where it was injection molded. Helps to true the wheels as well, although I've always found them pretty much round.
4) Lubricate w/graphite (all we're allowed) a lot, and spin the wheels a lot, before the meet.
5) Camber the axles up a few degrees. This causes the wheel to want to move away from the body. Wheels rubbing against body is bad. Camber too much though and they push too hard against nail head, again increasing friction.
6) You can shave (carefully) the profile of the wheels so they run on an edge, not the whole surface. Note that cambering the axles should have this effect, and over-profiling the wheels can result in disqualification.
7) Raise one axle so car runs on 3 wheels. Not so sure. In theory, less rolling friction (3/4 to be exact...) and no energy stored in spinning up the 4th wheel. However, if the car wobbles at all, varying which 3 wheels are touching, I could see this being a net negative as different wheels would be spinning up/slowing down. Hard enough to get the damn thing to roll straight on 4 wheels (stay on 4 wheels!!).
8) "Aerodynamics" The first car was pretty much aerodynamic - but had "shark fins" on the back that didn't help. The 2nd was the aforementioned football helmut. The 3rd was a "missile laucher" with a big ass rocket out the front. I don't even remember last year's car (thank God this is the last). Some guy's cars are professionally finished - I mean race car lines and a paint job better than my real car. I prime the car (spray) and my son hand paints whatever he wants. He also spoke shaves (if needed), rasps, and sands the body before priming (thus this year we needed a round of Bondo to fix some "design misfeatures"). Needless to say, 6 - 10 year olds aren't too great with hand tools and sanding is boring as hell. He used the spokeshave at 6 - it can be done - just need to supervise. They're not the greatest looking cars, but they run okay because we pay attention to the fundamentals - max length, weight distribution, reduce the real friction factors (non-aerodynamic). Any drilling, etc he does. I do the bandsawing and any chisel work (because the risk of a slip). Obviously, a 10 yr old whose helped make 4 cars can do a lot more than a 6 yr old on his first.
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My grandson just did it this past weekend, he finished about the same. Somewhere near last. He had fun though. He called me all upset, because after the race a wheel broke off. Placing the weights just forward of the rear axle seems to be the right place.
Chris
Jim wrote:

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