Boomilever B/C

[PayalParikh]

Hi, I have a question if anyone can help us with.

The base of our boomilever always comes from both the tension bars attach point. Its kind of glue failure. It does not break, the whole base pops out. Our whole boomilever stays intact most of the time, this is mostly our failure point.

We have tried different types of glues - CA blue, CA purple, Super glue, Titebond wood glue. Nothing seems to work. It usually comes out around 10-12 kgs load.

We have even tried to reduce size, increase size of base every possible thing that we can think of.

Another thing we tried was splitting wood in thin strips and trying to wrap around the base piece like a tape.
Can anyone please help us?

Gorilla glue

Clear Gorilla glue or original Gorilla glue.

[MadCow2357]

Hi, I have a question if anyone can help us with.

The base of our boomilever always comes from both the tension bars attach point. Its kind of glue failure. It does not break, the whole base pops out. Our whole boomilever stays intact most of the time, this is mostly our failure point.

We have tried different types of glues - CA blue, CA purple, Super glue, Titebond wood glue. Nothing seems to work. It usually comes out around 10-12 kgs load.

We have even tried to reduce size, increase size of base every possible thing that we can think of.

Another thing we tried was splitting wood in thin strips and trying to wrap around the base piece like a tape.
Can anyone please help us?

Gorilla glue

Clear Gorilla glue or original Gorilla glue.

i use original, though I've heard that it doesn't matter which one you use

[lechassin]

Not that we expect folks to divulge their secrets, but for "C" (high school), have any of the predictions of scores up to 3000 panned out at this year's width and height? It's hard to imagine a 7.5 gram boomilever holding 15kg at these dimensions.

We have two 10 gram boomilevers that are basically the same: traditional tension design with 1/8" x 1/16" basswood tension cords, 1/4" x 1/8" firm balsa compression cords and pad pieces (all with the cross-sections horizontal), 1/32" x 1/16" cross and vertical triangulation with two inch gaps, that stay under tension due to slight bowing built into the compression cords, minimal hook. They hold the 15 kg without too much deformity but trying to get any one part of the design to weigh fractions of a gram less results in catastrophic failure that cannot be repaired. Not that 10 grams is a fast build, but we seem to be able to reproduce that.

7.5 grams just seems impossible!

[michiganmarc]

Not that we expect folks to divulge their secrets, but for "C" (high school), have any of the predictions of scores up to 3000 panned out at this year's width and height? It's hard to imagine a 7.5 gram boomilever holding 15kg at these dimensions.

We have two 10 gram boomilevers that are basically the same: traditional tension design with 1/8" x 1/16" basswood tension cords, 1/4" x 1/8" firm balsa compression cords and pad pieces (all with the cross-sections horizontal), 1/32" x 1/16" cross and vertical triangulation with two inch gaps, that stay under tension due to slight bowing built into the compression cords, minimal hook. They hold the 15 kg without too much deformity but trying to get any one part of the design to weigh fractions of a gram less results in catastrophic failure that cannot be repaired. Not that 10 grams is a fast build, but we seem to be able to reproduce that.

7.5 grams just seems impossible!

I think someone posted that a Div C team achieved a 2700 score, which would be 7.41g. I can totally believe that with the kinds of scores we're seeing now (we are not that high yet...). I don't really want to share any of our secrets at this time, but it's definitely possible to get sub-9g boomis holding the entire load.
3000 would require a 6.67g boomi. That would be pretty exceptional. We placed 3rd at Nationals last year with a 7.0g boomi holding ~14.95kg for an actual efficiency of ~2135. If a 6.67g boomi holds 15kg, its actual efficiency would be 2249 which would be as good as 1st place at Nationals last year. The rules are harder this year with the 8cm width requirement. I'm not saying it's impossible, but if it happens, it'll be very rare. I do know that there were 2400-2500+ scores last year, but not at Nationals, which means those types of scores are very rare and not easily repeatable.

The real question in my mind, is are the sub-9 or sub-8g boomis reliable enough and repeatable enough to bring to major competitions. We'll see!

[Lorant]

Yes.

[hmma]

Yes.

No.

[hmma]

Not that we expect folks to divulge their secrets, but for "C" (high school), have any of the predictions of scores up to 3000 panned out at this year's width and height? It's hard to imagine a 7.5 gram boomilever holding 15kg at these dimensions.

We have two 10 gram boomilevers that are basically the same: traditional tension design with 1/8" x 1/16" basswood tension cords, 1/4" x 1/8" firm balsa compression cords and pad pieces (all with the cross-sections horizontal), 1/32" x 1/16" cross and vertical triangulation with two inch gaps, that stay under tension due to slight bowing built into the compression cords, minimal hook. They hold the 15 kg without too much deformity but trying to get any one part of the design to weigh fractions of a gram less results in catastrophic failure that cannot be repaired. Not that 10 grams is a fast build, but we seem to be able to reproduce that.

7.5 grams just seems impossible!

I think someone posted that a Div C team achieved a 2700 score, which would be 7.41g. I can totally believe that with the kinds of scores we're seeing now (we are not that high yet...). I don't really want to share any of our secrets at this time, but it's definitely possible to get sub-9g boomis holding the entire load.
3000 would require a 6.67g boomi. That would be pretty exceptional. We placed 3rd at Nationals last year with a 7.0g boomi holding ~14.95kg for an actual efficiency of ~2135. If a 6.67g boomi holds 15kg, its actual efficiency would be 2249 which would be as good as 1st place at Nationals last year. The rules are harder this year with the 8cm width requirement. I'm not saying it's impossible, but if it happens, it'll be very rare. I do know that there were 2400-2500+ scores last year, but not at Nationals, which means those types of scores are very rare and not easily repeatable.

The real question in my mind, is are the sub-9 or sub-8g boomis reliable enough and repeatable enough to bring to major competitions. We'll see!

I can see 9g being reliable, but sub 9 is tough to build repeatedly good

[123445]

Does the speed at which the sand is dispensed affect how well a boom does? Because I've always just assumed that if a boom can hold 15kg it will hold 15kg no matter what. Also if the bucket tilts it shouldn't matter, right?

[sneepity]

what does a tower chimney boomilever look like, and what is the difference between a compression boomilever and a tension boomilever? Also why is everyone freaking out about the 8cm rule

[sneepity]

Does the speed at which the sand is dispensed affect how well a boom does? Because I've always just assumed that if a boom can hold 15kg it will hold 15kg no matter what. Also if the bucket tilts it shouldn't matter, right?

i think only the length of the chain matters, but i dont clearly know too..
how long do they usually hang the bucket from?