Elevated Bridge B/C

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Re: Elevated Bridge 2009

Post by andrewwski » January 10th, 2009, 2:25 pm

I find you generally want thin glue. If it's thin enough to soak into the wood, then the joints have glue that is soaked all the way through the wood, not just on the surface. I'd think this results in greater shear strength as you're subject to ripping the few layers of bonded grain from the rest of the piece.

I can't imagine that thick CA would give that great of results. Seems like it wouldn't bond porous substances such as balsa very well. I'd recommend thinner CA.

Of course, the thinner the messier as well.

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Re: Elevated Bridge 2009

Post by croman74 » January 10th, 2009, 2:27 pm

andrewwski wrote:I can't imagine that thick CA would give that great of results. Seems like it wouldn't bond porous substances such as balsa very well. I'd recommend thinner CA.

Of course, the thinner the messier as well.
Also if the glue is thinner it would be lighter.
Oh, and for me, the thinner glue was actually neater as the top of the bottle was skinnier so the glue wouldn't squirt out.
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Re: Elevated Bridge 2009

Post by WrightStuffMonster » January 10th, 2009, 4:53 pm

croman74 wrote: Also if the glue is thinner it would be lighter.
I am not sure if thin CA is lighter per unit of volume than thick CA but thin CA can be very heavy if applied improperly as it soaks through the wood so sometimes its hard to tell how much you applied unless you are doing it a few drops at a time. I recall the first time I used thin CA for the distal end of one of my booms it added .6 grams in glue over the wood glue that I had been using before. If you build with CA make sure you have a way to apply a very small amount at a time or else the weight in glue will quickly add up.
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Re: Elevated Bridge 2009

Post by Aia » January 10th, 2009, 6:52 pm

January 10th- I just returned from the invitational I supervised.

The bridge event was kind of disappointing. Due to severe flooding, many teams were not able to make it to the competition. I'll post what I can though.

Only four bridges were tested, all of which were in a very early building phase. Most kids had only built 1-2 bridges before the competition. 2 structures were built right before the event, and half the teams did not even enter a bridge.

The top score was somewhere around 650, the lowest efficiency was 4. Two bridges were disqualified for being too tall.

Today's results are probably not a good indicator for what you'll see in this event. If the flooding weren't so bad, more teams would have brought devices and scores would have been much higher.

Sorry I can't offer more information- blame the weather gods. : /
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Re: Elevated Bridge 2009

Post by sciolykid101 » January 10th, 2009, 7:08 pm

Aia wrote:January 10th- I just returned from the invitational I supervised.

The bridge event was kind of disappointing. Due to severe flooding, many teams were not able to make it to the competition. I'll post what I can though.

Only four bridges were tested, all of which were in a very early building phase. Most kids had only built 1-2 bridges before the competition. 2 structures were built right before the event, and half the teams did not even enter a bridge.

The top score was somewhere around 650, the lowest efficiency was 4. Two bridges were disqualified for being too tall.

Today's results are probably not a good indicator for what you'll see in this event. If the flooding weren't so bad, more teams would have brought devices and scores would have been much higher.

Sorry I can't offer more information- blame the weather gods. : /
I had a lot of rain too today. :x
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Re: Elevated Bridge 2009

Post by smartkid222 » January 10th, 2009, 7:09 pm

that sucks aia
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Re: Elevated Bridge 2009

Post by Grace » January 10th, 2009, 7:16 pm

Today we had Wayzata Invitationals in Minnesota. My bridge was very light compared to most bridges, weighing only 25.8 grams. The materials I used were balsa wood grain C and very thin CA glue. My bridge broke in half down the middle holding about 24.6 pounds (a little more than 11 kg), which got us 2nd place. I definitely know what it needs next time for improvement. :D
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Re: Elevated Bridge 2009

Post by andrewwski » January 10th, 2009, 8:17 pm

4! Did that even hold the bucket?

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Re: Elevated Bridge 2009

Post by sr243 » January 10th, 2009, 8:42 pm

yea it probably did, but it would be like 100g and only hold the bucket, lol. I didn't do towers last year and guess what happened, a 60g tower. Just a very heavy bridge.

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Re: Elevated Bridge 2009

Post by Aia » January 11th, 2009, 8:35 am

andrewwski wrote:4! Did that even hold the bucket?
It was a heavy bridge and only held the weight of the chain and loading block. We had to use the gram scale to measure how much it held.
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