Author Topic: pinewood derby car (Read 1499 times)

Mr Mom · « **on:** January 28, 2010, 10:09:10 pm »

Did all the shaping and sanding now where is the best place to put the extra weight??
I thought about in the front right behind the front tires.
Then i though about in the middle.
Thanks Alot Mr Mom

isawlogs · « **Reply #1 on:** January 28, 2010, 10:14:06 pm »

Feed the driver more milk and cookies before the race .

beenthere · « **Reply #2 on:** January 28, 2010, 10:25:21 pm »

Low and in the middle. If anything, towards the rear. The front wheels steer the car down the center rail. The rear wheels follow.

Make a practice ramp with the strip down the center, and tweek until the car will run down the track and across a smooth floor going straight. Any turning, means the wheels are rubbing the side of the center strip on the way down.

Don_Papenburg · « **Reply #3 on:** January 28, 2010, 10:25:54 pm »

Pinewood derby drivers are distant relatives to pinochio .
I would put the weight low and slightly forward of the mid section

Jeff · « **Reply #4 on:** January 28, 2010, 10:33:28 pm »

Polish the axles (nails) to a mirror finish and make sure there are no deformations inside or outside of the wheel and get some graphite for lube.

Magicman · « **Reply #5 on:** January 28, 2010, 10:52:39 pm »

Chuck the nails/axles in your drill and use 400/600 grit emery cloth and then steel wool to polish. After assembly, spin the wheels. They should run "smooth as glass". No vibration. Graphite is your friend.

Angle of departure.....Remove wood so that there is no overhang in front of and behind the axles. You don't want the body to touch the track as it levels out on the straight-away.

CHARLIE · « **Reply #6 on:** January 28, 2010, 11:01:17 pm »

It was a looooong time ago........ I tried the weight in the front, the middle and the back. I had the best luck with the weight in the middle. My son's car, and he built it all by himself except for putting in the weights, came in 1st in his Pack and 8th out of 254 entries of a race for scouts in the whole city of Rochester, Minnesota.

When I put the weight (molten lead poured into holes drilled in the wood) in the front, the car did well on the down hill but really slowed down fast when the track leveled out. I don't remember but I think that when I put the weight in the back, it was slow on the downhill and picked up speed when the track leveled out.

The next year, my son built his car exactly the same and we placed the weights exactly the same and the car didn't win anything. Go figure.

isawlogs · « **Reply #7 on:** January 28, 2010, 11:31:55 pm »

Guess we are not talking soap box cars here are we

$:-\$ Sorry must be a translation things . So milk and cookies aint gonna help in any way ...

In them little cars , keep it low and centered. When you think the axles are polished enough .. give it a little mor epolishing .

Ironwood · « **Reply #8 on:** January 29, 2010, 04:31:05 am »

Weight to the rear, POLISH axles (as stated), graphite, polish inside of rims (where the axle runs), debur the injection mark on outside of rim, and try a "quick start" front end (high and thin, getting you out the gate QUICKER) think shoe horn, arch down.

Ironwood

Chuck White · « **Reply #9 on:** January 29, 2010, 05:32:49 am »

Whew!!!!!
It's been a lot of years since my boys were in Cub Scouting, but they did all the carving and shaping and then "we" drilled a hole from the bottom, near the center and screwed a bolt in the hole for weight.

Quote from: isawlogs on January 28, 2010, 11:31:55 pm

Guess we are not talking soap box cars here are we $:-\$ Sorry must be a translation things . So milk and cookies aint gonna help in any way ...
In them little cars , keep it low and centered. When you think the axles are polished enough .. give it a little mor epolishing .

These cars are around 1½" wide and 8" long (I think), and have a max weight limit.
The boys are supposed to carve them, with minimal parental supervision/help.

Mr Mom · « **Reply #10 on:** January 29, 2010, 06:48:38 am »

We get to test the car tonight and play with ajusments. Race is sat 10am.
Will put weight low and in middle.
Got graphite.
Never thought to polish the inside of the wheel
Did polish the axles.

Thanks Alot Mr Mom

Ironwood · « **Reply #11 on:** January 29, 2010, 07:25:30 am »

Next year we are trying cryogenic treatment of the axles

Ironwood

red oaks lumber · « **Reply #12 on:** January 29, 2010, 05:52:22 pm »

we make the pinecars for the boy scouts.. part of the deal is i can't share info. with anyone, just think areodynamics and low center of gravity
good luck with your racing

Ironwood · « **Reply #13 on:** January 29, 2010, 06:35:48 pm »

Red,

I notice some are very dense, others not so. Any requirement to keep them w/ in a tolerence of density?

tughill · « **Reply #14 on:** January 29, 2010, 08:14:00 pm »

I shouldn't tell anyone this, but I have no kids, and my friends kids are not in scouts, so what the heck.

The best secret that I ever heard that actually worked was to take the block and drill the grooves where the axle pins push in, on a drill press so they are 100% square and don't need to get hammered in, but just a hand tight friction fit. Mashing those axle pins in doesn't help wheel alignment, or probably the straightness of the pins.

red oaks lumber · « **Reply #15 on:** January 29, 2010, 08:53:53 pm »

ironwood,
the only restiction is on weight we can't be over 4.3 oz. lighter is ok just add more weight. the style we make has 2 axle slots milled in the bottom, slot widht is .088 +- .002 slot paralell is +-.002 the axle is one piece that is press fit in the slot. so far this fall/winter we have shipped 120,000 still have 30,000 cars to go. i suppose i might let my arm be twisted in suppling cars strickly for r&d purposes only. isn't that what nascar does? after all aren't these cars raced in the name of father pride?

Ironwood · « **Reply #16 on:** January 29, 2010, 09:09:19 pm »

Thanks, we'll see. I honestly think the cryo will help. It is all about friction. Our local BSA is fairly strict. Nothing but BSA tires, nails, and block. No grooves machined in the axles, no aftermarket anything. I use it to discuss a ton of cool science stuff w/ my 7 year old.

Tonight's fun was magnatizing the ends of screw drivers w/ a powerful magnet, he is setting up a test to see how long it lasts. The electron aligment should only last soooo long. Tomorrow he wants to make his own electro magnet w/ some old cotton covered blasting wire from up at the shop, a bolt and a battery. We cannabilize all sorts of toys that are electrified, and we glue stuff to them for him to use w/ legos and knex, he uses them to motorize them .

Ironwood and Son's

Ironwood · « **Reply #17 on:** January 29, 2010, 09:12:07 pm »

He also brought home a heat sensitive pencil that we are having fun w/ the color changing from friction or just breathing on it.

Ironwood

Mr Mom · « **Reply #18 on:** January 29, 2010, 09:15:17 pm »

Well if the kids were to build them themself i a monkeys uncle.
There were some that i do not think that a kid could build but maybe,maybe not.
Some were just realy flat pices of wood.
My kid did really good but not the best.
need to add more weight.
We get 5oz max. We are 4.4 need to add more.

Thanks Alot Mr Mom

Ironwood · « **Reply #19 on:** January 29, 2010, 09:24:04 pm »

I just make sure he is involved in every aspect, running what tools he can, etc... The quickstart front is important, and getting right at 5 oz, it took 20 pennies for us to hit it this year. I like light pine (thanks Red), that way you can really put the weight to the rear. It should balance 2/3 of the way back to the rear axle. Make sure you bevel the axle nailhead away from the plastic rim and get rid of those darn sets of three grooves they held them w/.

Ironwood

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Author Topic: pinewood derby car (Read 1499 times)