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Does anyone have a good design for a pinewood derby car?
- Thread starter Riprorin
- Start date
OREOSpeedwagon
Diamond Member
AlienCraft
Lifer
I wanna build one....
Well you are going to find so much crap going on with the cars you wont believe it.
Turning the wheels in a lathe so only the inside of the wheel touches the track, polishing the nails that are used for the axels with diamond dust. and many other things. a wedge with most of the weight behind the back wheels is the way to go. No paint, go to a hobby shop and get some solarfilm to cover it with, smooth and shiney.
Bleep
Turning the wheels in a lathe so only the inside of the wheel touches the track, polishing the nails that are used for the axels with diamond dust. and many other things. a wedge with most of the weight behind the back wheels is the way to go. No paint, go to a hobby shop and get some solarfilm to cover it with, smooth and shiney.
Bleep
AgaBoogaBoo
Lifer
My younger brother is doing one too. From our experience the weight in the back or balanced out evenly like what amused described works best. If the weight is in the back make sure it is balanced well.
my collection
from right to left:
tiger cubs one. didnt win at all.
first year cub scout. won first place.
second year cub scout. won 3rd place.
third year cub scout. didnt win a thing.
2nd year webelo. (first year, didnt compete). won style award, and 3rd place speed. modeled on 1903 winton.
always remember to grease your nails for wheels, and always remember to sand the wheels on a drill press.
from right to left:
tiger cubs one. didnt win at all.
first year cub scout. won first place.
second year cub scout. won 3rd place.
third year cub scout. didnt win a thing.
2nd year webelo. (first year, didnt compete). won style award, and 3rd place speed. modeled on 1903 winton.
always remember to grease your nails for wheels, and always remember to sand the wheels on a drill press.
It's not so much the design as it is the weight and how you line it up on the track.
You'll want to make sure the wheels spin just perfectly (maybe if you have a real tiny file or something run it through the hole in the wheel a couple of times to make sure it is smooth) and that when you line it up on the track everything is balanced and straight.
The only time I did it, my brother got first place and I got second. Both of our designs were a bit stream lined with some metal weights right on the underside of the car.
You'll want to make sure the wheels spin just perfectly (maybe if you have a real tiny file or something run it through the hole in the wheel a couple of times to make sure it is smooth) and that when you line it up on the track everything is balanced and straight.
The only time I did it, my brother got first place and I got second. Both of our designs were a bit stream lined with some metal weights right on the underside of the car.
DrPizza
Administrator Elite Member Goat Whisperer
A lot of people are convinced that it needs a really smooth surface to minimize wind resistance... they couldn't be closer to the truth, yet so far from the correct idea.
Simple physics principles: you are turning potential energy into kinetic energy. More weight toward the back means more potential energy (they start on a slight slant.) Make sure you have a method to hit the exact maximum weight allowed.
MOST IMPORTANT PRINCIPLE: you cannot avoid friction. It's just that air friction isn't the #1 friction for these cars. The number 1 source of friction is where the wheel turns on the nail. The simplest fix: bevel the nail head where it touches the wheel - and lubricate the nail-wheel interface with graphite. It's not as hard to do as it may sound, takes about 20 minutes of work. If you were to look at it under a magnifying glass, you'll see that the nail is far from smooth. That's what you need to fix.
Make sure the car runs straight (so it isn't constantly bouncing off the guide rail; also a potential source of friction.
My son didn't win overall, but he finished in the top 10%, blowing away a majority of the other cars. It's pretty clear that polishing the nails is getting to be a better known design enhancement (especially since a majority of the kids in cub scouts also have internet access, and you can bet they'll also all be looking for tips.) Most importantly, let your son do most of the work. I only showed my son how to polish the nails.. the rest was up to him. In fact, his car split in half about 30 minutes before the race as a result of him trying to pound a nail through it to gain weight... He still managed to exceptionally well.
Simple physics principles: you are turning potential energy into kinetic energy. More weight toward the back means more potential energy (they start on a slight slant.) Make sure you have a method to hit the exact maximum weight allowed.
MOST IMPORTANT PRINCIPLE: you cannot avoid friction. It's just that air friction isn't the #1 friction for these cars. The number 1 source of friction is where the wheel turns on the nail. The simplest fix: bevel the nail head where it touches the wheel - and lubricate the nail-wheel interface with graphite. It's not as hard to do as it may sound, takes about 20 minutes of work. If you were to look at it under a magnifying glass, you'll see that the nail is far from smooth. That's what you need to fix.
Make sure the car runs straight (so it isn't constantly bouncing off the guide rail; also a potential source of friction.
My son didn't win overall, but he finished in the top 10%, blowing away a majority of the other cars. It's pretty clear that polishing the nails is getting to be a better known design enhancement (especially since a majority of the kids in cub scouts also have internet access, and you can bet they'll also all be looking for tips.) Most importantly, let your son do most of the work. I only showed my son how to polish the nails.. the rest was up to him. In fact, his car split in half about 30 minutes before the race as a result of him trying to pound a nail through it to gain weight... He still managed to exceptionally well.
WinkOsmosis
Banned
How do you get your wheels aligned perfectly? Some kind of laser calibration machine??? Seems like that would be the biggest factor.
Supermercado
Diamond Member
Actually, we've found through eight years of derby car building between my brother and I that the weight is better off in the back as much as possible.
I'm the older of the two of us so we didn't really know much what to do when I built my first few cars. They always won appearance awards but never did anything speed-wise until my last year when I won everything in the Pack and went to districts, but didn't do so well there.
The next year my brother was the right age to start building Pinewood Derby cars and my dad took all the knowledge that we'd gotten from my cars and built some really good cars with my brother. I think he won the Pack every year but one (he finished second) and did pretty well at districts (the races he lost there can be attributed to a different track than the one our Pack used - different slope killed his car).
My dad got pretty crazy with it, though, especially with my brother. For several weeks, they'd work on the car every night. They spent so much time sanding and greasing and lubricating. It was crazy. They used so much lube on the wheels, they spun like crazy if you just barely touched them.
Good memories, though. I wish I could go back in time or something and build some more cars. I didn't really appreciate it for what it was when I was doing it. Heh, for the record, my best (fourth) car never quite beat even my brother's worst car. It was close, though. 🙂
When we went thru this, I made the decision that (unlike all the rest of the kids) my son would actually make the car himself. I did the research with him, and I made my own car, because I really like to, but he did his own everything except actually using the power tools until he was into second or third grade.
First year he lucked into a pretty good car, but the judges screwed up the scoring and had a rematch and they had messed up the track so cars didn't stay on, so they randomly awarded first to some kid who had connections, instead of my son. (Welcome to the real world.) It was pretty devastating for him, so the next year he made a car just for fun, decorating it with Pikachu which was just becoming popular, and he got a lot of attention for his really cool design.
Third year he did another really interesting car, and got a reputation for interesting designs. Also, it was completely obvious that his cars were COMPLETELY made by him, which a lot of people found interesting.
After that, he studied on the web for fast carmaking and actually won first place his last year in cub scouts. And he did it on his own.
"Competitive" is a relative term. We turned it away from a "my dad's engineering shop can make a cooler, faster car than your dad's engineering shop" competition into a "what's the best I can do on my own" competition. When he won that trophy all by himself it was the sweetest thing on earth, after what he had been through.
You live or die by the wheels (round) and the nails (smooth and straight). Tracks vary; if there is any way to practice on the actual track and then make one for yourself that is exactly the same, it helps. Memorize the rules, especially for track clearance and for local variances. You don't want to lose on a technicality or hang up on the starting mechanism.
First year he lucked into a pretty good car, but the judges screwed up the scoring and had a rematch and they had messed up the track so cars didn't stay on, so they randomly awarded first to some kid who had connections, instead of my son. (Welcome to the real world.) It was pretty devastating for him, so the next year he made a car just for fun, decorating it with Pikachu which was just becoming popular, and he got a lot of attention for his really cool design.
Third year he did another really interesting car, and got a reputation for interesting designs. Also, it was completely obvious that his cars were COMPLETELY made by him, which a lot of people found interesting.
After that, he studied on the web for fast carmaking and actually won first place his last year in cub scouts. And he did it on his own.
"Competitive" is a relative term. We turned it away from a "my dad's engineering shop can make a cooler, faster car than your dad's engineering shop" competition into a "what's the best I can do on my own" competition. When he won that trophy all by himself it was the sweetest thing on earth, after what he had been through.
You live or die by the wheels (round) and the nails (smooth and straight). Tracks vary; if there is any way to practice on the actual track and then make one for yourself that is exactly the same, it helps. Memorize the rules, especially for track clearance and for local variances. You don't want to lose on a technicality or hang up on the starting mechanism.
Looks like the tips have already been given (heck only 4 moving parts, only so much you can advise on) Curious though, have any of you ever had side competitions outside of the official derby race?
Dad's race. Obvious one. Track's there, many of the dads are building the cars anyway, why not let them have their own race?
1 hour from bag to track race. Kids are randomly assigned bare kits and must build the cars in front of other competitors in an hour.
Guess it depends how many competitors there are already, if there are 300 there the day is pretty full as it is. There were only a half dozen kids in my pack so after those weeks of testing and tuning it was a 10 minute race and that was it. Kind of disappointing (even though I won). Next year I go screwed due to politics (That kid's car weighed closer to a bowling ball! But his dad was an assistant scout leader), then lost the homebuilt kite competition in another political move and quit. Politics and parental overinfluence ruin most things about scouting, which is what made me think of the above two events. Personally I think the axles and wheels should be handed out on race day.
Dad's race. Obvious one. Track's there, many of the dads are building the cars anyway, why not let them have their own race?
1 hour from bag to track race. Kids are randomly assigned bare kits and must build the cars in front of other competitors in an hour.
Guess it depends how many competitors there are already, if there are 300 there the day is pretty full as it is. There were only a half dozen kids in my pack so after those weeks of testing and tuning it was a 10 minute race and that was it. Kind of disappointing (even though I won). Next year I go screwed due to politics (That kid's car weighed closer to a bowling ball! But his dad was an assistant scout leader), then lost the homebuilt kite competition in another political move and quit. Politics and parental overinfluence ruin most things about scouting, which is what made me think of the above two events. Personally I think the axles and wheels should be handed out on race day.
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