Pine wood durby

[John Rist]

I just received an add from Tower Hobbies for precision pine wood derby wheel.

"The Pro Ultra-Lite Derby Wheels weigh in at an amazing 1 gram each, and with 100’s of hours of testing on our track – B.S.A. Racing and a League Championships under their belt, you can be assured these are not just any lightened and weakened 1 race wonders. We start with select mold number matched sets and C.N.C. machine them both inside and out to remove the maximum amount of mass from the wheel in all areas for maximum speed, but retain strength and durability. While the exterior of the wheel remains completely stock, all interior markings are removed. They work well with all lubricants (graphite or racing oils) and feature a Reamed and Burnished hub bore for easier alignment and greater speeds, plus both hub faces have been coned for greater friction reduction."

Cost $37.  So another racing sport that has gone to the dogs.  $$$$$$$$$

[Brett Buck]

I just received an add from Tower Hobbies for precision pine wood derby wheel.

"The Pro Ultra-Lite Derby Wheels weigh in at an amazing 1 gram each, and with 100’s of hours of testing on our track – B.S.A. Racing and a League Championships under their belt, you can be assured these are not just any lightened and weakened 1 race wonders. We start with select mold number matched sets and C.N.C. machine them both inside and out to remove the maximum amount of mass from the wheel in all areas for maximum speed, but retain strength and durability. While the exterior of the wheel remains completely stock, all interior markings are removed. They work well with all lubricants (graphite or racing oils) and feature a Reamed and Burnished hub bore for easier alignment and greater speeds, plus both hub faces have been coned for greater friction reduction."

Cost $37.  So another racing sport that has gone to the dogs.  $$$$$$$$$

   This is inevitable, Pinewood cars are highly constrained, so it follows the usual rules for any performance event - the more you constrain the equipment, the more experts will dominate it (and as a corollary, the more expensive it will be be to optimize the performance).

     Brett

[bob whitney]

oil is drag  ,i built an adults derby car . i put rc car bearings in all 4 wheels .when i oiled them it was about the slowest car on the track then i used a go cart trick and flushed them out with thinner and ran them dry, it became the fastest car on the track.
  for the legal derby car ,cut a groove in the middle  nail which cuts down on surface drag and u can pack it full of graphite and it will last longer. if u are not aloud to add graphite after the races start.
  my Den took top 3 places at distrct two years running.also had a trick for aliening the nails so they were straight  .
  light wheels are good but overall car weight needs to be at the max .think it is 5 oz  and seems to be better if the extra weight is added to the rear of the car DEN LEADER RAD

[Brett Buck]

  light wheels are good but overall car weight needs to be at the max .think it is 5 oz  and seems to be better if the extra weight is added to the rear of the car

   Yes, because the car sits on the track nose-down, moving the CG aft gives you more potential energy.

     Brett

[Dan McEntee]

    Pinewood Derby sales were a pretty big thing at the hobby shop that I worked part time at. We couldn't get a Boy Scouts of America dealership to sell official BSA stuff, we sold the after market stuff from Woodland Sceneics. They have a great line of accessories and parts. With most of the activity in my area, you had to at least use the wheels that came with the BSA issued kit, so that protected their sales of those. Over the years I learned a lot from customers as they figured out easy does it ways to improve performance with what they gave you. I had to deal with the Dad's that were McDonnell-Douglas engineers coming in and claiming that they put their kid's car in the wind tunnel and yada, yada, yada, but in the long run, I learned through my own experience with Sean in his Scout days was to make the car weigh as close to the weight limit as possible ( 5 ounces?? I think? ) and make the car balanced.  Make the car roll as straight as possible so it's not constantly banging against the guide strip where it would scrub off speed. They were not allowed to bush the wheels at all, which were really loose and wobbly on the axle nails, so make those as close a fit to the car and the head of the nail as possible to reduce any wobbling. I did this by putting a piece of business card stock on the nail, then the wheel (after making sure there was no flashing sticking out anywhere) then another piece of business card stock on the nail. I took C/C glue and used it to coat the wood on the body where the axles pushed it  to harden it and make it slick, and then sanded that as smooth as possible. Push the nail in until there was some draw on it from the card stock, then pull the card stock out. test roll the car and get it rolling straight. When satisfied, reinstall the wheels and secure with glue. next step is to use unscented furniture polish and spray a dab on each axle, and then have the kid spin the wheels for an hour or so to polish everything in. You have to make sure the nails don't have any globs of cadmium or flashing from dipping them on them also. Those simple steps, when done correctly, will yield a pretty fast car. I helped a lot of single Mom's and/or Dad's that never did anything hobby wise get a decent car that won some prizes, and often just using kitchen utensils!! It was much later on that the wheels became a "thing" with some of the parents. Each wheel has a number on it, and that's the number of the cavity that the wheel was made in on the mold. They probably mold 2 dozen at a time as I remember seeing a lot of 2 digit numbers. If the operator sees any defects in the parts, he then knows which cavity to look at and work on. So somebody starts the rumor that you want wheel with the number 17 on the inside! Those were supposed to be like magic!! It didn't matter to them that there might be two or three injection molding machines pumping these things out and all with the same cavity numbers!!It was fun working with people though. It used to be that the Scout Derby season was between Halloween and Thanksgiving, to give all the troops plenty of time to hold their events. Some troops had their own tracks to run on, and some had to share one that got passed around. Last time I checked, it goes a lot longer these days and we even had other types of kids groups doing it so it's almost year round now. What's ridiculous is the clowns that sell "Race Ready, Derby Winning Cars" on eBay for crazy money, and people buy them!! And if you're wondering, Sean DID build his own car! I did the band sawing and such, but he did everything else. It was a Batman car that resembled the movie Batmobile, and he won a trophy for "Best Looking" car. They also had a Dad's Class and I kicked major butt there with one that I patterned after the midget racer my wife's Dad used to wrench on in the early 60's.
  Type at you later,
   Dan McEntee

[kenneth cook]

                  The Pinewood Derby tournament when I participated had a very large turnout. We had one kid who just dominated. Upon inspection of his car it was noted that his father instructed him to use electrical tape over the area that supports the nails for the wheels. They disqualified him and my father was pretty hot over that. The rules were pretty clear as to no axles, bearings, bushings. Reading Dan's post, this a very similar method.  My dad was arguing that this was very innovative and nothing in the rules state tape and he deserves the win. I was in third place and seeing this individual was disqualified, I was moved to second and I didn't like that either. I never even hear mention of the event today.

[Dave Hull]

The original Scout house that invented the Pinewood Derby is a few blocks away from me. Lots of history there! My cars were decent, but tended to look fast rather than be that fast. Our Scoutmaster made some really trick cars that in no way, shape or form were legal. But they weren't that fast either--too much weight in the aluminum wheels to accelerate, regardless of the instrument ball bearings. My favorite was his candy apple purple and black Batmobile. Who knew Dads were into that kind of thing in the 1960's?

[Dan McEntee]

The original Scout house that invented the Pinewood Derby is a few blocks away from me. Lots of history there! My cars were decent, but tended to look fast rather than be that fast. Our Scoutmaster made some really trick cars that in no way, shape or form were legal. But they weren't that fast either--too much weight in the aluminum wheels to accelerate, regardless of the instrument ball bearings. My favorite was his candy apple purple and black Batmobile. Who knew Dads were into that kind of thing in the 1960's?

       We had a customer at the hobby shop who, after getting his boys through the derby stages, took up making solid wooden car model built from scratch. Even pick up trucks!! Their Derby cars were always pretty cool looking, but the Dad took things to another level. I used to see him at local toy shows with some set out to sell and there didn't seem to be much interest there, which I found odd since a big chink of the tables are usually guys selling Hot Wheels cars and old plastic model car kits. I don't know what "scale" a derby car might be, 1/32?? But there are lots of accessories available for them that are made of white metal for weight, and if up sized to 1/24 scale there are unlimited choices in after market and excess kit detail parts.
   Type at you later,
    Dan McEntee

[Brett Buck]

The original Scout house that invented the Pinewood Derby is a few blocks away from me. Lots of history there! My cars were decent, but tended to look fast rather than be that fast. Our Scoutmaster made some really trick cars that in no way, shape or form were legal. But they weren't that fast either--too much weight in the aluminum wheels to accelerate, regardless of the instrument ball bearings. My favorite was his candy apple purple and black Batmobile. Who knew Dads were into that kind of thing in the 1960's?

  If it is worth doing, it is worth doing to excess!

  BTW, when I was poking around the internet out occasionally curiosity, I saw that the "standard wheels" were not the same as before. The old wheels were solid hard polystrene or something and symmetrical. It looks like the new wheels are one-sided hollow plastic, and off hand it looked soft. Nonetheless, various people are selling "improved" wheels and usually putting them on a lathe and thinning them out to reduce the moment of inertia - and selling them at 10X the list price.

     Brett

[Doug Moon]

They always say weight at the back. When we did them when my daughter was big into animals. So one year we made a car that looked like a shark. I carved it and she painted it and glued in the axles and I cut the slot for the weights and she glued them in. Then she glued on the to fins I had cut out Dorsal and Tail. The main round portion of the body was forward like a shark. I crammed all the weight in there I could right on front. Got it right on 5oz exactly. Then I took a Dremel with a polishing wheel and spun the wheels up many times over a week period leading up to the race. We got most animal like!   We were also 4th fastest out of about 35 cars. The other 3 faster were the typical skinny front with all weight at the back. One guy I know paid $30 for some tiny but super heavy weights so he could concentrate it all at the back (we beat him by a mile). We were .00055 out of first or something like that. They all ran very close. It was cool. I have heard if you can get it to sit on 3 wheels its even faster. Our Shark kicked ass and we built it.

We also made a dinosaur, very slow. Just like a real one. Most animal like.
We also made a rainbow complete with pot of gold and clouds at each end. VERY SLOW.
We made a Lego brick. Pretty fast for its shape.
And we made a Wii controller, hahahah. That one cracked me up because it was pretty darn fast and looked so out of place, big white block going down through there with all the racers. hahahaha. Wow that brought back alot of memories..

[Steve Helmick]

My son Daniel (named after Dan Gurney) made one that looked like a rounded wedgey thing. He did all the work on his, except I probably worked on the nail axles and maybe sprayed the yellow paint.

Mine was a pretty close copy of the Cox Thimbledrome sprint car, also yellow, with wheel spokes painted silver, O-ring steering wheel with sheet aluminum spokes, aluminum dash panel and a really nice sheet aluminum grill on the nose. As I recall the rules, we had to use all the kit wood parts, and I needed to add some wood to the top above the "gas tank" area, so I sawed some off the top front and glued it onto the top rear. The slots in the grill were done with a Sharpy and sprayed over with spraycan clear of some sort, and it still looks pretty good. Both are still downstairs on a shelf.

I don't remember how we finished...we had kids and adult comps...but we had fun. One of the Dad's had a '32 chopped Fjord coupe, which I recall was red with yellow flames, headers and stuff. Pretty cool to see the creativity.  Steve

[dave siegler]

to get the weight right at the max value, a few collogues would put their slightly overweight cars in a vacuum chamber, to pull moisture out of the wood.  I a little insane

[John Rist]

to get the weight right at the max value, a few collogues would put their slightly overweight cars in a vacuum chamber, to pull moisture out of the wood.  I a little insane

We  always came in deliberately heavy.  Had several flat head brass screws in the bottom.  Removed screws until the car made weighin.  That way we were at the max the official scale would allow. 

[Dan Berry]

When I raced one the rules specified that you could only use what was supplied in the kit.
When did they start allowing other stuff?

[Dan McEntee]

  If it is worth doing, it is worth doing to excess!

  BTW, when I was poking around the internet out occasionally curiosity, I saw that the "standard wheels" were not the same as before. The old wheels were solid hard polystrene or something and symmetrical. It looks like the new wheels are one-sided hollow plastic, and off hand it looked soft. Nonetheless, various people are selling "improved" wheels and usually putting them on a lathe and thinning them out to reduce the moment of inertia - and selling them at 10X the list price.

     Brett

   Official BSA wheels have changed over the years. They used to be solid plastic like you say, and then people would spin them in a drill or drill press and taper the outer circumference to a sharp edge to reduce friction. They evolved into the newer style that can't be reworked like that. Requiring that the kids must use the kit wheels was one way of leveling the playing field. I just told people to make sure there were no burrs where the nails went through , and on the hub where it would rub the body and make sure that was flat. The nails were such a bad fit in the wheel that they could wobble, but you can't bush the wheels either. So polishing the shaft of the nails became important and then polishing the bore of the wheels to make them match. Install the wheels using a piece of paper on each side the set the clearance, and then repeated application of furniture polish followed by long sessions of spinning the wheels would create a bit of wax build up to improve the fit and then when graphite was applied it would help keep the graphite from working it's way out while spinning. The wheels will rub against the body where the axles go in, so harden that with a light coat of C/S glue then polish that smooth with 600 wet or dry and a flat block. We experimented with how the car sat some what, and that was a function of balance. I always balanced the car. Lots of discussion on whether to put the weight in the front to "pull" the car down the track or in the back to "push" the car down the track has been made over the years. But the biggest thing about the car running down the track is that it must run as straight as possible t o avoid banging against the guide strip and scrubbing off speed. Rolling the car on a tile floor so you can gauge how straight it rolls against the lines helps you understand that part of it. Truing the grooves for the nails with a table saw helps a lot there. Then you set the car on 4 small pieces of paper under each wheel, and if you pull the pieces out, it will move the wheel and the car. The nails are were a loose fit that you could center one nail in the wheel, and when you pulled the paper out, the wheel would turn but not move the car. To make this work the car needs to be balanced. A balanced car will run more straight down the track. There isn't a race car on any race track anywhere in the world that isn't balanced. It's a bit of work doing all of this, but every little bit helps. I don't think aerodynamics matters at all. I coached one dad who came into the shop one morning asking for help and when I asked him when the race was and he said "TONIGHT!" ( This happened a lot!! Lots of frantic Moms and Dads in a panic to get a car done) I suggested that he just break the corners of the wood block with a sanding block, paint the thing brick red, add the words "ACME BRICK COMPANY" to the top and spend as much time on the wheels and axle fits as he could and make it roll straight. he came back in a couple days later and said they had a 2nd or 3rd place finish and won a prize for funni3st entry!  The thick block leaves plenty of room to add weight. The common BSA kit components all weigh about 2.5 ounces when put on a scale, so making the body all lowered and thin just puts you in danger of not being able to get up to max weight. We all know that the finish can add weight so I would suggest to people to really lay on the sanding sealer and the paint along with clear. In the end, the speed of the car will be in relation to the amount of work and attention to details that are put in it, just like in any kind of racing!!
 Type at you later,
  Dan McEntee

[Lauri Malila]

.

[John Rist]

While we are reviling deep dark secrets here goes.

!: Add all of the weight to the back of the car to make it tail heavy.  Then raise one of the front wheels a few thousands.  This get rid of the friction of one wheel.  Of course make sure the car still tracks straight on a flat floor.

2:  When we were active Cub Scout members the wheels were of the wide tread style.  I would buy the Cub Scout Den car kit.  I forgot how many set of wheels came in the kit but I would put the wheels on a axle (nail that came in the kit) and spin each one.  I would pick the 4 best ones.

3:  This is hard to describe but I would drill 3 1/16" holes in the hub.  I would start on the outside side of the wheel and drill at a 45 deg angle into the center of the axle hole.  Once The car was finished I would fill outside cavity of each wheel with graphite power.  I would then place a hubcap made out of Monocoat trim sheet material to contain and hide the graphite.  Of course I placed a white dot sticky label on the inside center of the hubcap to make sure it didn't stick to the head of the axle nail. What this did was feed graphite onto the center of the wheel each run.  This of course pushed the limit of no modifications to the wheel but we were never called on it.

4: We used the graphite that was sold for HO coupler lubrication.  I was finer and slicker than regular graphite.

5: when I firs got into pinewood racing a machinal engineer ran some numbers on air drag.  At the max speed the car could reach air drag was not a factor.  The shape of the car makes no differences. So I always let my boys be in charge of building the car body.  I was in charge of the wheels.

Having said this all of the polishing of nails etc. as stated else where goes without saying.  We did win most of our races.  What did help was that I built the track for our pack and stored it in my garage.  Giving us a of lots of test time on the track.  I am now 84 years old but when My two boys were Cub Scouts that was some of the best years of my life.

[Dick Pacini]

The Pinewood Derby cars and races often led to interest in the Soap Box Derby, which had the finals in Akron Ohio, if memory serves me right.

The race cars were built to a spec and were based on wheels and axles that you bought from your local Chevrolet Dealer.  Chevrolet was the sponsor for many years.  The cars were gravity powered and carried the young boy or girl down a hill and free running wheels and low wind resistance were very important.  Most cars looked alike with the biggest differences being paint color and graphics.  I believe the covering of the frame was canvas.  I don't know if the Derby still exists but it was very popular when I was a kid.

[Brett Buck]

The Pinewood Derby cars and races often led to interest in the Soap Box Derby, which had the finals in Akron Ohio, if memory serves me right.

The race cars were built to a spec and were based on wheels and axles that you bought from your local Chevrolet Dealer.  Chevrolet was the sponsor for many years.  The cars were gravity powered and carried the young boy or girl down a hill and free running wheels and low wind resistance were very important.  Most cars looked alike with the biggest differences being paint color and graphics.  I believe the covering of the frame was canvas.  I don't know if the Derby still exists but it was very popular when I was a kid.

  Still exists although Chevy is long gone.

    The Model Airplane "Plymouth Internationals" was sold sold to Plymouth as the aviation version of the Soap Box Derby. The problem is that they limited entry to 18 and under or something like that. That meant that the vast, vast majority of the competitors were already too old or quickly aged out (like Aldrich). The slightly questionable aspect was that the sales pitch about "youth aviation education leads to the leaders of tomorrow" that the AMA and everyone uses to sell model aviation had not been true since about 1928.

     Model aviation has not been primarily about kids since the Lindberg craze ended*, it is about adults, and no one cares about adults flying little toy airplanes. The AMA is still using the same sort of sales pitch today. Plymouth noticed this, too, and that's why it only went for a few years and then petered out.

     Brett

*replaced shortly later by the biggest "technology boom" ever, specifically, radio, which had much broader appeal and went until the TV boom replaced it.