Pinewood Derby Rules

General race coordinator discussions.
rpcarpe
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Re: Pinewood Derby Rules

Post by rpcarpe » Fri Jan 04, 2013 10:53 am

When possible, like for Pack races... we publicly announce which track will be used. And if I'm running the inspection table, each car gets put on a piece of track, or the curve (like Best Track) to make sure the weight doesn't scrape.

Barring foreknowledge of the track type, enforce the 3/8's rule for the reasons Stan (the man) explained.


My wife started a new support group... Widows of the Pinewood Derby.

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Re: Pinewood Derby Rules

Post by tims » Fri Jan 04, 2013 4:49 pm

rcmoeur wrote: First, thanks for the considerable "in-town" feedback. We weren't aware that San Tan was dealing with many of the same concerns (I've been trying to make contact with other Districts with mixed success).

The 3/8" bottom clearance is recommended, not mandatory. If there's a problem, it'll unfortunately be self-enforcing, as the car scrapes the track.

We used a go-no go box last year at District, but it may have been part of an (expensive) track rental. May have to buy one, or ask tonight at Roundtable to see if a Pack has one to lend.

Wheelbase may continue to be an issue, and the rules address it (Pack races can allow long wheelbases, but District has to be within "near-box" limits). If there's consensus for dropping the wheelbase rules, it could be omitted. And if there is a Council committee to standardize rules, I'm hoping to be on it - and I'll see if I can drag you onto it as well.

So... are you up to bringing your family's cars to compete in our Open Class on March 23? Registration should be up on the District page in the next week or so... :)
Thanks, keep me posted on the Council wide activities, would be glad to participate!

In San Tan, there's a group at one of the LDS's churches in Gilbert that has hosted the District races the past two years. Really nice track, the whole setup. However there's not that much participation, given that the San Tan District is one of the largest in the state. Numbers were up this past year, I think because they did a better job of publicizing it? Not sure. It's kind of late in the year, so unfortunately for the older boys (Webelos II) many have already bridged to Boy Scouts. It's actually a very well ran event, despite having to pull your wheels off the car every year :sigh:

The winning cars are pretty fast, in the high 2.8's / low 2.9's on a 40ft 6 lane freedom track. The build quality of the cars and times in general were much faster in 2012 than 2011 and that's kinda cool.

If we're in town that weekend sure! I'll check the district website, and talk to my boys about it.



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Re: Pinewood Derby Rules

Post by rcmoeur » Thu Jan 24, 2013 7:07 pm

FYI: we just opened registration for the Four Peaks District Pinewood Derby.
http://www.grandcanyonbsa.org/event/1294447" target="_blank
Although we received a lot of very useful feedback here, the decision is to leave the rules alone for now. But there is a possibility that detailed axle inspection may be deferred until after racing is complete.



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Re: Pinewood Derby Rules

Post by rcmoeur » Fri Mar 29, 2013 12:39 am

This past weekend was the Four Peaks District Pinewood Derby which generated so much discussion over the past couple pages.

All in all, it went extremely well. Thanks to a gang of excellent volunteers (mostly Boy Scouts), everyone had a great time. And I mean everybody. Well, except one parent, who thought we were being too lenient on weight. But even he sat down and watched the race. And if I only had one somewhat-irate parent the entire day, I can certainly call that a success. :bigups:

We also allowed the Cubs to stage & retrieve their cars, unlike previous years. I think we'll stick with that. And we sent out a questionnaire asking Cubs what the car name was, who helped them, what they liked about the car, etc. We posted the best answers (anonymously) on posters at the event.

So, how did the actual rules go? First, let me introduce you to our Chief Inspector, Bob:
Image
Bob had lots of fun looking at all the carefully-crafted wooden creations and checking their compliance to three decimal places.

And out of the 80+ cars, we only identified two as being clear candidates for inspection requiring removal of wheels. And we'd agreed that such an inspection would wait until after racing was completed, so as not to mess up any tuning or alignment. When Bob would encounter such a car, he'd explain that the car would be allowed to race, but would be held after the event for a supplemental inspection.

The responses were interesting. One car was identified, and raced without wheel removal. However, for some reason the car & its owner didn't return for the finals race - we can only presume that there was some sort of scheduling conflict. When it came to the other car, the owner immediately volunteered to pop the wheels off right then to present them for inspection - and we found out that this driver had definitely paid attention to the rules, as the wheels came out precisely at 1.170" diameter and 2.45 grams each (although it might seem that the rule against machining the wheels may have been slightly overlooked). The car was permitted to race, as it precisely met the defined minimum criteria.

As noted in other message areas, we found out empirically that it's danged near impossible to assess the provenance of axles. Bob had a full array of BSA axles in various levels of finishing for reference, along with Revell brand Peoples' Revolutionary BSA-blessed axles (OK) and PineCar axles (not OK). And without doing a ridiculously-obsessive 3-D dimensional analysis, we weren't going to be able to unambiguously weed out aftermarket axles. So we did our best and focused on anything obviously questionable (factory-graphite-coated, etc.) And didn't see much if any of that.

So what will we likely look at revising next year? Here's a short list:

Wheels:
- go to 1.180" minimum diameter
- specify tread thickness (measure a bunch o' wheels or get from you guys here at Derby Talk)
- specify tread width
- allow hub bore step removal
- allow shaving only to correct out-of-round
- state that any clearly visible evidence of machining of wheels will be grounds for rejection of those wheels (such as "H" grooving or a lip, step, or groove on the inside of the wheel indicating removal of material from the inside of the wheel)

Number of Wheels:
Some cars in the Pack races had more than four wheels, and looked & ran great. But the District rules called for four and only four wheels (3 touching), so most of them didn't move up (one did by popping off the spare ones). We're thinking of changing the rules to allow a minimum of four, all within the maximum allowable wheelbase (see next comment below).

Wheelbase:
Our very first car at inspection had an extended wheelbase far beyond what was clearly called out in the rules. The way we handled it was to offer two options: a move to Open Class (Plummet), or the use of our onsite Pro Body Tool (and a hand drill) to move the wheelbase to legal limits. The wheel move was chosen, and the car successfully raced in its rank.
But this raises a question: should there be a wheelbase limit, other than the 5 13/16" practical maximum? I'm inclined to be OK with it, but Bob's a bit dubious. We'll see what we work out.

Weight:
Next year, we'll be absolutely clear: 5.00 ounces, measured to 0.5 g or 0.02 oz precision. And we do have a reference weight.

Lubricants:
We don't have a reliable test for silicone, Krytox, or Nyloil. We may add a rule stating that any liquid lubricant observed leaving the car at any time is grounds for disqualification (graphite's enough of a mess).

"Proxy" racers:
Boys are busy on weekends, and some really wanted their cars to be there even if they couldn't. So, we'll add a rule saying that if a car owner can't be there in person, another Cub Scout may represent them - but the substitute will be fully responsible for the car, including answering all questions.

Webelos II:
We heard some Webelos didn't participate because they'd been fortunate enough to have their Arrow Of Light prior to the event. We'll make it clear that if they start the year as a Webelos II, they can race, regardless of crossover status.

And we'll probably split the rules into two parts for modularity: a section focused on car specifications, and then a supplement stating event-specific rules that can be modularized by Packs and Districts if needed while still keeping the cars uniformly-specified.

We'll get some more rest, and then see how it goes... :zzz:



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Re: Pinewood Derby Rules

Post by Speedster » Fri Mar 29, 2013 5:16 am

I thought I read in your rules you did away with the measuring of wheels and minimum size. I apparently was mistaken. Way back when this was being discussed I ordered a set of 1.180 machined wheels to see what they looked like. I then took a wheel out of a new box and went to work on it with my shaver. The wheel started out with the smallest area of the diameter being 1.187. When I neared 1.180 I began to tape various grades of sandpaper over the blade until I duplicated the look of the machined wheel. I see now I will be allowed to remove the outer step so I'll do that using Sporty's method. I have followed all the rules. The fellow behind me in line bought machined wheels from a vendor. Our wheels look the same. What if the guy was in front of me and admitted he bought machined wheels? I'm in trouble.



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Re: Pinewood Derby Rules

Post by Stan Pope » Fri Mar 29, 2013 9:28 am

rcmoeur wrote:...
Wheels:
...
- allow shaving only to correct out-of-round
- state that any clearly visible evidence of machining of wheels will be grounds for rejection of those wheels (such as "H" grooving or a lip, step, or groove on the inside of the wheel indicating removal of material from the inside of the wheel)
Better to focus on the RESULT rather than the INTENT. Better to focus on what you CAN inspect and not on what you CAN'T. How the wheels got round is not important. That not too much material was removed is important.


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Re: Pinewood Derby Rules

Post by Stan Pope » Fri Mar 29, 2013 11:32 am

rcmoeur wrote:As noted in other message areas, we found out empirically that it's danged near impossible to assess the provenance of axles. Bob had a full array of BSA axles in various levels of finishing for reference, along with Revell brand Peoples' Revolutionary BSA-blessed axles (OK) and PineCar axles (not OK). And without doing a ridiculously-obsessive 3-D dimensional analysis, we weren't going to be able to unambiguously weed out aftermarket axles.
Consider applying minimum and maximum diameter limits on axles as measured in the gap between body and hub. This requires a pair of thin smooth gages. Since the axles are often not round, this is slightly more complicated than first glance would indicate.

To check the lower limit, assure that from some direction the "low" gage does not fit over the axle. (This looks like it would also catch wheels whose bores were artificially reduced in diameter, thus requiring axles whose diameter was similarly reduced.)

To check the upper limit, assure that from all directions the "high" gage does fit over the axle.

Since the gages are constructed of thin spring metal and they are intruding into an area of the car that has been carefully polished, a very light touch is necessary and the gage must have no sharp edges. The gage must not be "forced."

I have not looked at what those limits should be, nor have I looked at the thinning or fattening effects of bending axles.

BTW, :thumbup: for having the boys participate as "drivers" (staging their own cars) instead of being "spectators" (watching staff stage their cars!)


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Re: Pinewood Derby Rules

Post by resullivan » Fri May 03, 2013 9:01 am

I know this a month old, but I was thinking about how you could enforce not using oil and the only thing I came up with was to have the inspector apply some graphite on the axles. I don't see how this would be a problem unless you had oil.



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Re: Pinewood Derby Rules

Post by Scrollsawer » Fri May 03, 2013 9:30 am

You may have already covered this in your rules, but if you are going to take a rigid stance on wheel specs., I would also be rigid about canting (as in "no canting allowed"). I am all for rigid rule sets in Packs (or not), but I often see canting used as a way to get the tread off of the track (i.e., riding on the edges of the wheels) versus doing it for the sake of moving the wheels out to the axle head to reduce axle/wheel friction. If the rules allow canting, hey I'm all for it, but our Pack has a rule that states "wheel tread must remain parallel to, and in contact with the track at all times (except for the raised wheel of course).

Just a thought, since I do see canting used for reasons other than reducing wheel/axle friction.

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Re: Pinewood Derby Rules

Post by Speedster » Fri May 03, 2013 9:47 am

I think no one should be puffing hardware store graphite, or anything else, into a scouts carefully Hob-E-Lubed bores. This is the scouts car and it's either legal or not. Let's find another way to identify the folks who have misinterpreted the rules.



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Re: Pinewood Derby Rules

Post by Speedster » Fri May 03, 2013 10:19 am

We have that silly canting rule also and it can't be enforced. Any angle on the rear axles will make the wheel ride to the axle head once the car starts rolling. When using the screw technique the axle can be angled and the wheel will still sit flat because there's a lot of slop between axle and bore. The same goes for the DFW. You don't need a 1 1/2 degree angle on the DFW. It's nice to have but you don't need it for success building a rail rider. I often wonder what the rule makers think when making these rules. Everyone wants a 6 to 10 year old child to build the car themselves, with a little help, and then make rules so it's impossible for them to do it. There is no rule that will stop an experienced builder from building a fast car. The only thing all these rules do is make it hard for a child to have fun building his car. The 4 on the ground rule is the worst rule ever made. We had folks this year breaking their cars trying to get the 4th wheel on the ground. One family left. Gosh !!! What Fun that must have been for the scout. My District is guilty of all these lousy rules. I'm doing my best to get them changed.
Thank You. My Blood Pressure has now returned to normal.



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Re: Pinewood Derby Rules

Post by Stan Pope » Fri May 03, 2013 1:36 pm

resullivan wrote:I know this a month old, but I was thinking about how you could enforce not using oil and the only thing I came up with was to have the inspector apply some graphite on the axles. I don't see how this would be a problem unless you had oil.
Okay, EXCEPT ... the application should be done by the owner/driver, not the inspector. He may use supplied high quality graphite (e.g. MaxV or Hodges) or may use his own. The inspector should simply observe that the application occurred! (This is current Wotamalo District rules.)


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Re: Pinewood Derby Rules

Post by resullivan » Fri May 03, 2013 1:47 pm

Either way the result is the same. I am all for open rules. In fact, I think oil should be allowed (inspection would make sure there isn't to much); however, of all the ways to "cheat" to me using oil is the most bang for your buck and can be difficult to catch. The only way a person would not want to add more of their own graphite would be if they had something wet on the axles. This would have to be made clear up front, so they can't say "I didn't know and didn't bring graphite." I do think graphite should be available (which it usually is) for those that did not have any.



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Re: Pinewood Derby Rules

Post by psycaz » Fri May 03, 2013 2:12 pm

Adding graphite usually will slow a car down for the first couple runs until it is worked in. Add too much and you can simply ruin a great running car to the point it needs to be completely reprepped from scratch. I've done it while testing cars. Car just goes away after adding graphite.



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Re: Pinewood Derby Rules

Post by Speedster » Fri May 03, 2013 3:26 pm

I agree, Mr. Psycaz. Too much graphite can really mess up a good running car. I'm not so sure oil instead of graphite is the biggest problem. I think 1.8 gram wheels might be a bigger problem. It takes someone familiar with the derby to catch them. I also think we on DT take a lot for granted. Many inspectors do not have the knowledge the folks on DT have. I'm not so sure you couldn't put 1.4 gram wheels, .093 axles on a car and it would pass our District inspection. A cheater is a cheater. It would be great if everyone had a knowledgeable inspector for their Pack and District races but I doubt many of them do.



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