Event called Boomilever

  • #26
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If you are struggling at 100 efficiency, the thing is either WAY overbuilt or you arent using good wood or something like that. Tell me about your boomi and maybe I can help you get on the right track.

What I have done with my boomi is virtually eliminate the need for vertical trusses by making the compression members into half I-beams. The horizontal trusses are absolutely necessary, however, to prevent side to side bowing, trust me. Besides, the tension members are going to be so thin that it would be nearly impossible to connect trusses to them.
 
  • #27
18
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I've had three boomilevers so far. The first was unevenly made, but mainly broke because the attachment base was, to say the least, lacking. The second was way too heavy for various reasons, but ostensibly held 13 kilograms (I think it was being aided with the bucket resting on the device that released the copper balls). The most recent one I tried weighed about 30 grams (largely, this was the attachment base) and held about 1.5 kilograms before the lower two legs of the base slipped, pulling apart all the struts rather spectacularly.

All three were designed something like the one in this topic, but upside down. I was told this was a viable way to go about it, but with my most recent test that seems to have been proven wrong. I'm going to try to emulate the design in the other boomilever topic. If that doesn't work, I'm kind of stuck.

I use entirely plain old balsa purchased from the local Hobby World, and some wood glue, with plywood for the attachment base.
 
  • #28
hey do you guys have any ideas for the attachment base? i'm from louisiana 8-B and am building a stress boomilever. The attachment base keeps ripping off?
 
  • #29
for the base part.. glue small pieces of wood around the stick.. like gussets. : )
 
  • #30
well, i was just doing some research on this...and balsa wood has a very high variation of different weights and strengths and what-not. what might help is weighing the wood and finding out the exact strength that it is. also, use C-grain balsa for the compressive parts and A-grain for the tensiles (if you suddenly decide to go balsa for bottom parts). Anyway, the way those...uh...triangles in the bottom work is by splitting the compressive forces into smaller sections. Try rearranging the pattern so the weaker areas are split into shorter segments. and if it still breaks then you just need to rethink your design.

thanks for the pic by the way, i have to turn in 3 designs of this in 2 days cause i'm doing this in place of a physics project. just got 1 done.
 
  • #31
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will some of you post your boomilever attachment base pictures on here i can't figure out how to make mine
 
  • #32
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I'm doing this as part of a class, not competing in the competition.
Have any of you tried a square boomilever, like the ones on a crane?
Also, laving an L with a connecting point from the top of the vertical truss to the end of the horizontal one seems to work best; wood loses strength per length in compression, but not in tension.

Also, what is "laminating" the wood?
 
  • #33
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your just putting a coat of material on it. I tried this, and it didnt really make my boomileve any more sufficient. It didn't a significant amount more, however, it did weigh ALOT more.
 
  • #34
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Say Hello To 3100!!!!
Woooottttt!!!!!!!
XD
 
  • #35
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an efficiency score of 3100?? sounds a tad unbelievable. your boomilever would have to weigh less then 5 grams, and hold ALL of the weight. If your lying.... -.- If your telling the truth.....WAY TO GO!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
  • #36
JC052341-- how do you make your base where the screw hooks to the board? My boomilever is always failure there.
 
  • #37
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I would like to preface this statement with saying that I believe the Science Olympiad is a wonderful idea to stimulate and cultivate young interests in the sciences. That having been said; This past weekend my youngest daughter competed in an Olympiad held at Southern Illinois University in Edwardsville. Given the perameters of the boomilever competition, she decided on a design that not only relied on tension, but also compression. I must say it was a very elegant design. The rules stated that an attachment plate would need to accomodate two 1/4 holes for 2"x1/4" bolts with washers 20cm's apart. This was critical to her design. Upon arrival to this phase of the competition she is told only one hole would be provided for a bolt. This was instrumental to the failure of her design. Not having an anchor at the abutment caused a catastrophic failure at the lower attachment point. In her design, she used lamination methods throughout the structure making it not only incredibly strong, but incredibly light. Being it held 14.5kg with the handicap, I can only guess what it might have held with the perameters she was given. Bottom line is she is happy,so I am happy. But I know she would have liked to have won. comments from a proud father.
 
  • #38
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hey guys, i dont want to beat any one from California or New york, i just wanna beat my teacher that pretty much stole my plans and built a boomilever with them, for another girl member on the team, and currently has an efficiency score of 888. My highest score as of now is 750, but thats not working!!!! I would REALLY appreciate it if one of yall would help me.
 
  • #39
3
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okay i'm working on this for a science olympiad in connecticut

my question is, with your 'scoring' formulas, is it mass supported (grams)/mass of boomilever (grams)? if so, how the hell do you support fifteen kilos with a five gram boomilever? or fifteen gram boomilever?

you must be doing something else, as a single twenty centimeter dowel weighs about ten grams if not more
 
  • #40
5
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yes, mass held (in grams)/ mass boomilever (in grams). Very simple....OUR DESIGNS ROCK!!!! I dont know how a 5 grams boomilever holds all of the weight (very suspicious if you ask me), but a 15 gram one seems possible. My best score now is just above 888 (haha, i beat that other chick by a couple points), and my boomilever weighs just under 16.9 grams. Im sure that if i lightened my load some, i could get it down to 15 grams.....anyways......Its all about design and forethought. What is your best efficiency score (include mass held and weight of your boomilever).
 
  • #41
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Hmmm well we haven't competed yet (this weekend) but our boomilever is 160 grams

In tests, without all the supports in place and the glue not set completely we got about 5 kilos haha but i'm gonna go get pics of it and finish it...

Our base is a little large but I'm planning to pop a lot of holes in it to drop the weight

Thanks!
 
  • #42
3
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k so just tested it and it held 6 kilos easy (no visible or audible signs of stress).

I couldnt find my postal scale so idk the exact mass of it. Buy it was 155 before I added some extra supports, then I drilled much of the base out.

Will have pics tomorrow if you're curious/wanna help. We threw a lot of different ideas into this that maybe you'll use idk
 
  • #43
5
0
Hmmm well we haven't competed yet (this weekend) but our boomilever is 160 grams

In tests, without all the supports in place and the glue not set completely we got about 5 kilos haha but i'm gonna go get pics of it and finish it...

Our base is a little large but I'm planning to pop a lot of holes in it to drop the weight

Thanks!
HOLY CRAP!!!!!!! 160 grams O.O .. and only 5 kilograms were supported......well, heres your problem: your design sux! - no offense or anything. You are most likely one of those people with no engineering skills whatsoever, and continue to add weight to your boomilever because you think that in the grand scheme of things, that extra weight would have helped.

Well....my team ins't going to nationals, and im a senior, so ill give you some help.
 

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