Boomilever B/C

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Tesel
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Re: Boomilever B/C

Post by Tesel » February 4th, 2019, 1:30 pm

Question about supervising Boomilever - any recommendations as to a scale for weighing sand for this event? I know a lot of people, myself included, usually used school equipment, but that's not currently an option for me. I appreciate any suggestions!
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Re: Boomilever B/C

Post by jinhusong » February 4th, 2019, 1:55 pm

Tesel wrote:Question about supervising Boomilever - any recommendations as to a scale for weighing sand for this event? I know a lot of people, myself included, usually used school equipment, but that's not currently an option for me. I appreciate any suggestions!
We use luggage scale. You can buy one from amazon. We also use that to test the tension stick strength and connection between base and tension members.

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Jinhu

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Re: Boomilever B/C

Post by knightmoves » February 4th, 2019, 2:22 pm

You can also use a bathroom scale if you have one. The digital ones might not register the weight of your sand bucket, but you can weigh yourself holding the bucket and yourself without it...

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Re: Boomilever B/C

Post by AlwaysLast » February 4th, 2019, 3:39 pm

Hey Guys,

I plan to start working on the event soon (A little late but at least it is not the week of regionals). I read through all of the forums for Boomilever and some for towers. I have not done this event before and still am relatively new to Science Olympiad. That means I still have a few questions.

1. How do you guys go about making a design for Boomilever? I know you're supposed to use Euler's Critical Buckling Formula but is there any tips you guys have besides this.

2. How do you select the perfect kind of wood and know which sizes are the best for each part? Is this just testing?

3. Is a jig needed for this event like towers?

Thank you! I have always lurked on here but never have made an account until now. I look forward to talking to some of you guys :D

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Re: Boomilever B/C

Post by Anonymous15 » February 4th, 2019, 3:53 pm

Hey!

I'm in a similar situation to you actually, but I'll answer your questions as well as I can.

1. Honestly, my designs were based off a lot of posts made on this forum. I would read the boomilever forums from years past (like 2013 and 2014).

2. Picking thickness is really just testing, but if you have a general idea of what your design will be, select a few different thicknesses that work with your design and test them all out. You also want to pick the best sticks within each thickness by testing for BS (discussed in Balsa Man's posts about Euler's Buckling Theorem). Here is a chart Balsa Man put on here that you can use to determine the best sticks. Test each stick for BS and whichever stick has a high BS compared to its weight (which you can determine using the chart) are the sticks you should use.

3. I have not been using a jig, and I can still build a boomilever pretty easily. Just make sure you're careful with the alignments-that's a problem I've faced a lot.

Good luck! If you can, build a few boomilevers before competition and test them, because even if you think your boomilever can hold full weight, there might be a problem you don't know about that can drop your score. Ideally, you would want to find these errors before competition.

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Re: Boomilever B/C

Post by MadCow2357 » February 4th, 2019, 6:03 pm

AlwaysLast wrote:Hey Guys,

I plan to start working on the event soon (A little late but at least it is not the week of regionals). I read through all of the forums for Boomilever and some for towers. I have not done this event before and still am relatively new to Science Olympiad. That means I still have a few questions.

1. How do you guys go about making a design for Boomilever? I know you're supposed to use Euler's Critical Buckling Formula but is there any tips you guys have besides this.

2. How do you select the perfect kind of wood and know which sizes are the best for each part? Is this just testing?

3. Is a jig needed for this event like towers?

Thank you! I have always lurked on here but never have made an account until now. I look forward to talking to some of you guys :D
1. I usually start by drawing out a basic design on a sheet of paper. Then I do the calculations and whatnot to find the thickness and density of the wood I need to build the boomilever, as well as my bracing intervals. But honestly what I've found works surprisingly well is just building a boomilever with a good basic design, and changing around the weights and sizes of each member each time. It's sorta like tuning a battery buggy, in a way.

2. You can test a piece's buckling strength with a single finger push down (SFPD). Just press down with uno finger on a piece that is perpendicular to the scale you are using underneath it. The weight at which it buckles is the piece's buckling strength. Not sure how you would test tension, but in my experience a member's overall strength has a pretty direct correlation to the buckling strength.

3. You may or may not need a jig, based on your design and your building preferences. I personally have not been using one, but I just built one to construct the new design I want to try out.
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Re: Boomilever B/C

Post by Anonymous15 » February 4th, 2019, 7:28 pm

Whoops just realized I didn't link the chart I mentioned earlier: https://docs.google.com/document/d/1I0Z ... LyvgQ/edit

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Re: Boomilever B/C

Post by AlwaysLast » February 5th, 2019, 5:37 pm

Thanks for all the info! A little update on my progress. I have gone back to find Balsa Man's posts (RIP) and that helped a lot with my understanding of this event. As for the jig, does anyone have a picture of what a jig would look like? I know for towers it was relatively simple but how would we do that for boomilever?

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Re: Boomilever B/C

Post by Dreamz » March 8th, 2019, 6:00 am

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?

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Re: Boomilever B/C

Post by dholdgreve » March 8th, 2019, 8:14 am

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.
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