Elevated Bridge B/C

andrewwski
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Re: Elevated Bridge B/C

Post by andrewwski »

Instead of spending so much time baking and experimenting with baking, you'd be more productive to spend that time working on other improvements to the bridge.
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Re: Elevated Bridge B/C

Post by Balsa Man »

I suspect the differences we've seen in dehydration/rehydration vs time curves may be mostly due to the difference in ambient humidity; much dryer out here, much wetter back there. We did one set of tests a couple years ago on a rainy day, and did see both the drying and rehydrating curves taking a bit longer, which reflects your observations.
Any wood is going to get to equilibrium with atmospheric moisture, and there is going to be some sort of time delay involved. The higher the density, and the greater the cross section, the slower the response. I'd think that the greater absolute amount of water involved at higher humidity would slow things down compared to smaller amounts at low humidity.

With the new wording added to the rules this year, that bridges will be weighed at the time of competition, I'm assuming the intent was to minimize any beneficial effect of......moisture management, and by and large, not completely perhaps, it will.

Thanks for re-emphasizing the heat will damage glue fact; I'd hate to see someone who has worked hard.....mess themselves up looking for that last little bit of help in the wrong place.

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Re: Elevated Bridge B/C

Post by croman74 »

I guess that it would be better not to bake and be on the safe side. Thanks for your help!
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Re: Elevated Bridge B/C

Post by rjm »

If you are really that interested in moisture management, you would do better to store and transport the bridge with a dessicant so that it dries out gradually, and stays at a moisture equilibrium right up to the point that you present it for judging. At least that way you won't be stressing the joints with a differential expansion/contraction or a thermal stress.

Yes, the rules were intended to limit the effect of dehydration/rehydration of a structure. Basically, the intent was that the bridge should be tested as presented and as weighed-in, so that there would be no weight changes or strength changes from sitting around in impound all day. Testing should occur within minutes of weigh-in.

I used to coach Odyssey of the Mind, and we competed against a team that would bring in their structure in a hermetically sealed container, with a light bulb and batteries mounted on it. It was most complex and intimidating. I'm convinced it was really just done to make us worry about it.

I agree with Andrewwski, spend your time improving your bridge, not exploiting gimmicks.

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Re: Elevated Bridge B/C

Post by computernerd4826 »

andrewwski wrote:Instead of spending so much time baking and experimenting with baking, you'd be more productive to spend that time working on other improvements to the bridge.
i agree entirely
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Re: Elevated Bridge B/C

Post by croman74 »

rjm wrote:If you are really that interested in moisture management, you would do better to store and transport the bridge with a dessicant so that it dries out gradually, and stays at a moisture equilibrium right up to the point that you present it for judging. At least that way you won't be stressing the joints with a differential expansion/contraction or a thermal stress.

Yes, the rules were intended to limit the effect of dehydration/rehydration of a structure. Basically, the intent was that the bridge should be tested as presented and as weighed-in, so that there would be no weight changes or strength changes from sitting around in impound all day. Testing should occur within minutes of weigh-in.

I used to coach Odyssey of the Mind, and we competed against a team that would bring in their structure in a hermetically sealed container, with a light bulb and batteries mounted on it. It was most complex and intimidating. I'm convinced it was really just done to make us worry about it.

I agree with Andrewwski, spend your time improving your bridge, not exploiting gimmicks.

Bob Monetza,
Grand Haven, MI
I store my bridge in a closed container with some rice. It doesn't do much, but it doesn't do any harm. I also agree that I should focus on improving the bridge. Thanks for your tips.
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Re: Elevated Bridge B/C

Post by sewforlife »

Bjsong wrote:Can anybody post an average ratio of their or somebody else bridge ratio of how much it could hold to how much the bridge weighed. I'm competing in the state tournament next week and i just want to get a sense of what state bridge scores are like.
one ratio that is about avg. is a 18.5 gram weight, holding all of the sand. which is about an 810 efficiency
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Re: Elevated Bridge B/C

Post by hbk.showstopper »

okay I get what you're saying but I think that it would be easier to build a tower instead of a bridge.
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Re: Elevated Bridge B/C

Post by hbk.showstopper »

well did it do good??
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Re: Elevated Bridge B/C

Post by hbk.showstopper »

:roll:
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