Which of the rules "in the box" prevents use of lathe?

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tomormatt
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Which of the rules "in the box" prevents use of lathe?

Post by tomormatt » Mon Feb 09, 2015 3:30 pm

Making my annual pilgrimage to DerbyTalk. Although I am no longer the Cub Committee Chair (our BSA Committee Chair for that matter) in our unit, I have been asked to run the Pinewood Derby again this year.

As background, our district has not typically had a Pinewood Derby so the rules for the pack derby have not needed to conform with district rules. Our district decided to do a derby last year and it seemed to go well. We did not restrict participants to winners or certain places at each pack in an effort to get as much participation as possible. I was a bit worried it would become too large and unwieldy, but the event was a success by all accounts. The decision to hold a district derby was made after we had disseminated our pack rules, but by sheer luck the rules were similar enough to not cause any issues.

This year, the district is still deciding on whether to hold a district derby so we each pack is once again going to have to decide their set of rules. My gut is that the district would use the rules that are in the box and I am leaning toward the same.

With that, my question is which of the rules prevents the use of a lathe and/or decreasing the weight of the wheel? I see the rule about having to use "official BSA wheels" and that they may not be cut, drilled, beveled, or rounded. The rules indicated that scouts can remove the seams and imperfections. The purpose of a lathe is obviously to ensure the dimensions of each wheel are equal and round; however, using a lathe to remove high spots would also seem to be removing "imperfections". Also, I am unsure which of the "cut, drilled, beveled, or rounded" prohibits removing mass from the wheel (e.g. plastic on the inner portion) / lightening the wheel or if that should be a separate rule.

I am trying to balance rules that would not give too much of an advantage to boys who have access to certain tools (computer lathe), but also avoid having rules that require too much time / complexity to enforce. Trying to determine if a wheel has been modified at the time of inspection could really slow the process.

Any help is very much appreciated.



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Re: Which of the rules "in the box" prevents use of lathe?

Post by Stan Pope » Mon Feb 09, 2015 4:30 pm

The last time that I read the "rules in the box" (RITB), there was no limit expressed on what could be done to the wheels. Nor a limit on where the axles could be placed, other than the must be placed so that the car fits inside the prescribed envelope.

What part of the RITB are you reading that justifies the limits you expressed?


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Re: Which of the rules "in the box" prevents use of lathe?

Post by ngyoung » Mon Feb 09, 2015 4:45 pm

I would suggest adding more details to remove the vagueness.
*No removing material from the inside. Min weight ~2.4g
*minimum tread width ~7.5mm
*removing outside hub double step allowed?
Etc.

Decide where you want to draw the line. What I listed so far I think allows for basic mods without completely opening the flood gates.



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Re: Which of the rules "in the box" prevents use of lathe?

Post by tomormatt » Mon Feb 09, 2015 8:10 pm

Sorry if I was not specific. The purpose of my post was to pose that question - do the RITB prevent the use of a lathe? I had assumed that the rule regarding rounding wheels would prevent the use of a lathe, but it is more because I cannot think of how else that would be applicable.

I am not opposed to adding more specificity if the RITB do not cover something; however, I am not very enthusiastic about adding rules that require too much time at inspection or are not easily verified. For example, weighing wheels would be something that I would anticipate being difficult to administer. I have thought about announcing that the winning car would have a post race inspection so we do not have to do each car.

Happy to have any suggestions on this. My experience is the wheels are where modifications can make the most difference. The axles can certainly be polished and modified, but the difference in a wheel that was 3.6 and a wheel that was 1.0 can be significant. I have seen several wheels that have the original BSA markings, but have had significant work performed to true the round and remove weight.



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Re: Which of the rules "in the box" prevents use of lathe?

Post by ngyoung » Mon Feb 09, 2015 9:50 pm

No. the rounding is for reshaping the tread surface to make it round, like a motorcycle tire. The tread shape needs to remain parallel to the bore. The box rules won't stop someone from turning wheels on a lathe to fix any imperfections in run out.

Yes wheel weight is not something most want to do. Here is a set of rules that are probably the best I have seen for balancing allowing some minor modification but limiting any weight reduction. The inspection also doesn't involve any car having to remove a wheel. It also makes it really clear what is allowed so there is not much guessing.
http://www.northernstarbsa.org/Forms/Ac ... yRules.pdf



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Re: Which of the rules "in the box" prevents use of lathe?

Post by Stan Pope » Mon Feb 09, 2015 11:56 pm

ngyoung wrote:I would suggest adding more details to remove the vagueness.
*No removing material from the inside. Min weight ~2.4g
*minimum tread width ~7.5mm
*removing outside hub double step allowed?
Etc.

Decide where you want to draw the line. What I listed so far I think allows for basic mods without completely opening the flood gates.
Are you proposing to weigh the wheels while still on the car? Or would you require disassembly?


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Re: Which of the rules "in the box" prevents use of lathe?

Post by ngyoung » Tue Feb 10, 2015 8:00 am

No. The list I made was mainly for examples. Having a wheel weight minimum isn't necessary. A 2.4g weight limit barely leaves enough room for turning the outside of the wheel on a lathe and removing the double step. Most lightening is pretty obvious just checking visually or by feeling the inside of the wheel when you prohibit it completely. If there is a dispute during inspection, as a last resort weighing a wheel can be an option. Could someone still fly under the radar with a visual inspection? Yes. However in my opinion I don't think you can take a significant amount of weight off before it will be detected.



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Re: Which of the rules "in the box" prevents use of lathe?

Post by bracketracer » Tue Feb 10, 2015 9:31 am

Why not just make a minimum diameter of 1.18" & .360" wide, then specify "no removal of material from inside the wheels allowed". It's quick and easy to check that with a $20 gauge from Max-V. Our rules also add that the wheels can't be drilled, spokes and lettering must be intact, etc. We don't allow for removal of the outer step either. Tough to check without pulling a wheel but since they're scouts we're on the honor system there.



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Re: Which of the rules "in the box" prevents use of lathe?

Post by tomormatt » Tue Feb 10, 2015 10:33 am

I like the suggestion on measuring the wheel (as long as standard wheels would not have enough variation to create a false positive). I also like inserting a rule preventing any removal of material from inside the wheel; however, just wondering if that is difficult to see without removing a wheel. I am not opposed to allowing holes for the axles to be drilled and axles glued so removing the wheel can be difficult.



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Re: Which of the rules "in the box" prevents use of lathe?

Post by gpraceman » Tue Feb 10, 2015 11:50 am

As long as they are not using wheel weights, you can flip the car upside down and look at the insides of the wheels. Though, if you are going to depend on doing so, you should have a rule that the lettering inside of the wheels must be visible. That won't necessarily preclude using wheel weights, as racers can use the type that fills only the upper part of the wheel. They just can't use the type that fills up the whole wheel cavity.


I would never recommend pulling wheels. To me, that is a destructive inspection, as it can mess up wheel alignment and can even lead to breaking wood off of the car as a wheel is pulled off. Check-in inspections should be non-destructive.
:soapbox:


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Re: Which of the rules "in the box" prevents use of lathe?

Post by Stan Pope » Tue Feb 10, 2015 12:36 pm

tomormatt wrote:I like the suggestion on measuring the wheel (as long as standard wheels would not have enough variation to create a false positive). I also like inserting a rule preventing any removal of material from inside the wheel; however, just wondering if that is difficult to see without removing a wheel. I am not opposed to allowing holes for the axles to be drilled and axles glued so removing the wheel can be difficult.
While some builders can inspect with gages during construction, many can not. Better to specify rule using wheel features. Our rule limiting rim mass removal uses the tread marks on the outer edge of the tread. Can specify that tread treatment leave (1) entire tread marks untouched, (2) portions of all tread marks be present, etc.


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Re: Which of the rules "in the box" prevents use of lathe?

Post by knotthed » Tue Feb 10, 2015 1:14 pm

I agree with Stan, no special tools required for the visual inspection using the tread bumps.

I would also recommend that you allow removal of the double step on the outside and coning the inner hub. This eliminates any additional problems of inspection.

Then you can consider if tapping the bore should be included as an ok as you cannot see it. I don't even know if there is any advantage to this treatment, but it is something that has been done in the past.

If you want to go the gage route, I would recommend the MaxV gage.



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Re: Which of the rules "in the box" prevents use of lathe?

Post by Noskills » Tue Feb 10, 2015 6:00 pm

I wrote my district rules. I allow for modication of the inner and outer hub and "light sanding" of the wheel. I then go on to define that light sanding will result in a wheel diameter >1.17 inches (and I will bring the gage). Additional requirements are no lath turning and no removing material from the inside.

This has been stated again and again....dont make any kind of rule like this if you dont have an inspector who knows what to look for. The only outcome of poorly enforced rules and pain and saddness. :cry:

I will be personally be running a finger along the inside rim of of every wheel and DQ'ing any with a lip. I will also measure any wheel that looks thin to my eye (and I have a pretty good eye) 8)
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P.S. Next year I am thinking of going with the mid American rule of just keeping all internal and external makings.


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Re: Which of the rules "in the box" prevents use of lathe?

Post by birddog » Wed Feb 11, 2015 1:29 pm

Noskills wrote:P.S. Next year I am thinking of going with the mid American rule of just keeping all internal and external makings.
I'm thinking of continuing on as District PWD chair after my son ages out next year. Once he is out, I think I'm going to propose that the district move to using the Mid America rule set completely. With this change, scouts could build one car for all 3 races instead of what we have to do today, which is build 1 car for pack/district, and then a more expensive car for Mid America.

I don't want to suggest this change while we are still in the program as I don't want anybody thinking we are making changes to some advantage we might have.

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