Boomilever B/C

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TheSquaad
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Re: Boomilever B/C

Post by TheSquaad » March 8th, 2019, 2:09 pm

dholdgreve wrote:
Dreamz wrote:Hey guys, wondering if y'all have had experience with baking boomilevers. I haven't tried it yet, but it seems like the wood would warp due to the different resulting moisture content and weaken my already-glued joints. Plus, I used Gorilla glue in a few places and it says on the bottle that gorilla glue should not be exposed to heat. Would the lattice of air bubbles that it forms when drying all pop? Also, what temperature and time would you recommend?
FWIW, We do not bake our structures, not because of what the heat may do to the wood, but what it might do to the glue. I believe that heat will drive off any remaining moisture in the wood and glue, this makes the glue brittle and suspect. Driving off the remaining humidity will result in only a temporary weight loss. As soon as the structure is exposed to ambient conditions, it will again begin absorbing moisture from the air until it reaches equilibrium... It depends on many things, but this usually will occur within 1 to 3 hours after exposure, but because most glues are not absorbent, they may remain brittle. Just not worth the risk IMHO.

If you do decide to try it, I'd recommend not baking over 250 degrees but over 212 degrees, and not more than 20 to 30 minutes. After you remove it from the oven, put it in an airtight container (think tuperware cake pan with locking lid), but again, I don't recommend it.
You can achieve a similar effect to baking a boomi by heat gunning it in the seconds before it’s weighed at competition. This evaporates some of the water in the boomi, but it regains most of its weight pretty slowly. We did this for towers last year and shaved off like .2 grams (which helps a lot when your device is sub 5 grams)

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Re: Boomilever B/C

Post by sciolyperson1 » March 9th, 2019, 6:38 am

TheSquaad wrote:
dholdgreve wrote:
Dreamz wrote:Hey guys, wondering if y'all have had experience with baking boomilevers. I haven't tried it yet, but it seems like the wood would warp due to the different resulting moisture content and weaken my already-glued joints. Plus, I used Gorilla glue in a few places and it says on the bottle that gorilla glue should not be exposed to heat. Would the lattice of air bubbles that it forms when drying all pop? Also, what temperature and time would you recommend?
FWIW, We do not bake our structures, not because of what the heat may do to the wood, but what it might do to the glue. I believe that heat will drive off any remaining moisture in the wood and glue, this makes the glue brittle and suspect. Driving off the remaining humidity will result in only a temporary weight loss. As soon as the structure is exposed to ambient conditions, it will again begin absorbing moisture from the air until it reaches equilibrium... It depends on many things, but this usually will occur within 1 to 3 hours after exposure, but because most glues are not absorbent, they may remain brittle. Just not worth the risk IMHO.

If you do decide to try it, I'd recommend not baking over 250 degrees but over 212 degrees, and not more than 20 to 30 minutes. After you remove it from the oven, put it in an airtight container (think tuperware cake pan with locking lid), but again, I don't recommend it.
You can achieve a similar effect to baking a boomi by heat gunning it in the seconds before it’s weighed at competition. This evaporates some of the water in the boomi, but it regains most of its weight pretty slowly. We did this for towers last year and shaved off like .2 grams (which helps a lot when your device is sub 5 grams)
Will this weaken the structure in any way?
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Re: Boomilever B/C

Post by TheSquaad » March 9th, 2019, 3:58 pm

sciolyperson1 wrote:
TheSquaad wrote:
dholdgreve wrote:
FWIW, We do not bake our structures, not because of what the heat may do to the wood, but what it might do to the glue. I believe that heat will drive off any remaining moisture in the wood and glue, this makes the glue brittle and suspect. Driving off the remaining humidity will result in only a temporary weight loss. As soon as the structure is exposed to ambient conditions, it will again begin absorbing moisture from the air until it reaches equilibrium... It depends on many things, but this usually will occur within 1 to 3 hours after exposure, but because most glues are not absorbent, they may remain brittle. Just not worth the risk IMHO.

If you do decide to try it, I'd recommend not baking over 250 degrees but over 212 degrees, and not more than 20 to 30 minutes. After you remove it from the oven, put it in an airtight container (think tuperware cake pan with locking lid), but again, I don't recommend it.
You can achieve a similar effect to baking a boomi by heat gunning it in the seconds before it’s weighed at competition. This evaporates some of the water in the boomi, but it regains most of its weight pretty slowly. We did this for towers last year and shaved off like .2 grams (which helps a lot when your device is sub 5 grams)
Will this weaken the structure in any way?
If it does it’s almost negligible. We tested identical towers last year, heat gunning one and not the other, and they both held roughly the same weight (note that there were about 2 minutes between heat gunning and actually testing)

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Re: Boomilever B/C

Post by Inihduma.aymar » March 10th, 2019, 12:23 pm

TheSquaad wrote:
sciolyperson1 wrote:
TheSquaad wrote:
You can achieve a similar effect to baking a boomi by heat gunning it in the seconds before it’s weighed at competition. This evaporates some of the water in the boomi, but it regains most of its weight pretty slowly. We did this for towers last year and shaved off like .2 grams (which helps a lot when your device is sub 5 grams)
Will this weaken the structure in any way?
If it does it’s almost negligible. We tested identical towers last year, heat gunning one and not the other, and they both held roughly the same weight (note that there were about 2 minutes between heat gunning and actually testing)
Did you use gorilla glue to build the towers?

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Re: Boomilever B/C

Post by retired1 » March 10th, 2019, 3:38 pm

Can not argue with actual figures, but 2 grams in 5 grams is 40%. Literature would rate this a WET balsa. 15% appears to be an accepted % for dry balsa and 5 % for dried balsa.
Moisture makes the device weigh more and lowers the tensile strength, moisture is not good. It will absorb moisture from the air (in Florida)
At one nationals, I saw a couple of teams that loaded the bottom of their "container" with silica gel and taped the edges of the top to the bottom. Is it worth the cost and effort? Not unless you have a very competitive design and assembly.
I know that balsa for wing ribs of Wright Stuff that is soaked and then dried in a curved device is a lot stronger than plain die or laser cut ribs. I have no idea of its weight.

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Re: Boomilever B/C

Post by TheSquaad » March 10th, 2019, 4:06 pm

retired1 wrote:Can not argue with actual figures, but 2 grams in 5 grams is 40%. Literature would rate this a WET balsa. 15% appears to be an accepted % for dry balsa and 5 % for dried balsa.
Moisture makes the device weigh more and lowers the tensile strength, moisture is not good. It will absorb moisture from the air (in Florida)
At one nationals, I saw a couple of teams that loaded the bottom of their "container" with silica gel and taped the edges of the top to the bottom. Is it worth the cost and effort? Not unless you have a very competitive design and assembly.
I know that balsa for wing ribs of Wright Stuff that is soaked and then dried in a curved device is a lot stronger than plain die or laser cut ribs. I have no idea of its weight.
It was actually 4%. The heat gunning dropped 0.2 grams, not 2 lol

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Re: Boomilever B/C

Post by TheSquaad » March 10th, 2019, 4:08 pm

Inihduma.aymar wrote:
TheSquaad wrote:
sciolyperson1 wrote:
Will this weaken the structure in any way?
If it does it’s almost negligible. We tested identical towers last year, heat gunning one and not the other, and they both held roughly the same weight (note that there were about 2 minutes between heat gunning and actually testing)
Did you use gorilla glue to build the towers?
I used cyanoacrylate

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Re: Boomilever B/C

Post by Inihduma.aymar » March 11th, 2019, 5:04 pm

TheSquaad wrote:
Inihduma.aymar wrote:
TheSquaad wrote:
If it does it’s almost negligible. We tested identical towers last year, heat gunning one and not the other, and they both held roughly the same weight (note that there were about 2 minutes between heat gunning and actually testing)
Did you use gorilla glue to build the towers?
I used cyanoacrylate
Wouldn't at some point the glue begin to liquefy again. I'm curious to know. Also, at what temperature did you set the heat gun to?

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Re: Boomilever B/C

Post by TheSquaad » March 12th, 2019, 6:34 am

Inihduma.aymar wrote:
TheSquaad wrote:
Inihduma.aymar wrote:
Did you use gorilla glue to build the towers?
I used cyanoacrylate
Wouldn't at some point the glue begin to liquefy again. I'm curious to know. Also, at what temperature did you set the heat gun to?
We never had problems with glue liquefying. To heat, we kept the tower in a box and point the heat gun at each corner for about 15 seconds at a time for 2 minutes, keeping the lid as closed as possible. We directed the heat gun at the box sides, not directly at our device. And I have no clue about the temp. I just hit the on button.

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Re: Boomilever B/C

Post by knightmoves » March 12th, 2019, 9:12 am

Inihduma.aymar wrote:
TheSquaad wrote: I used cyanoacrylate
Wouldn't at some point the glue begin to liquefy again. I'm curious to know.
CA glue polymerizes when it cures. CA glues may contain methyl cyanoacrylate, ethyl cyanoacrylate, or methoxyethyl cyanoacrylate, and polymerizes on exposure to water, and other things (that's why you can speed up the cure of CA by breathing on it, and why you need to keep your bottle sealed...)

All the cyanoacrylate polymers decompose on heating - typically this starts at around 150 °C. So baking below 150 °C "should" be safe from the point of view of weakening the glue. If you're running a hot heat gun over your build, you don't have as much control of the temperature you get to. Maybe someone has the knack of doing it.

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