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 Post subject: Re: Logos & Designs
PostPosted: Wed Feb 18, 2009 4:17 pm 
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Location: NE Minneapolis
garage would be better, but may be a bit brisk, and less than ideal for gluing, although contact cement is ideal adn nto too picky about temp.

i'm not sure what we'd need that i don't have, circ saw, jig saw, drill driver, hammers, mallets, saw horses.... a portable propane heater would do it. i'm near the quarry for target adn home despot, adn there's a menards nto too far up central.


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 Post subject: Re: Logos & Designs
PostPosted: Wed Feb 18, 2009 4:18 pm 
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and no an epilog lazer engraver/cutter. it's a baby one, but still would rock.

think of all the steps, makign cherries, laminating, tensioning springs....


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 Post subject: Re: Siege Engine and Cherry (aka spoonapult)
PostPosted: Wed Feb 18, 2009 4:43 pm 
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so.... assumign a grapefruit sized bean bag, how much force do we need to exert to fling it abotu 50' assuming 40% efficiency. suppose that's about a pound of beans?

i used to be able to solve that sorta thing in my head in college, but the abacus up there is a bit rusty.


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 Post subject: Re: Siege Engine and Cherry (aka spoonapult)
PostPosted: Wed Feb 18, 2009 4:44 pm 
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or do we want to get serious and do this with rope instead of springs?


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 Post subject: Re: Siege Engine and Cherry (aka spoonapult)
PostPosted: Wed Feb 18, 2009 4:46 pm 
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Location: Eagan, MN
metis wrote:
or do we want to get serious and do this with rope instead of springs?

I don't know how well a rope spring would scale down. We could try starting with loops of twine or string.

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 Post subject: Re: Siege Engine and Cherry (aka spoonapult)
PostPosted: Wed Feb 18, 2009 4:49 pm 
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it works ok, part of the tension is actually the wooden frame but it's a might bit more prone to nonpassive failure, although less violent when experiencing that than a metal spring.


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 Post subject: Re: Siege Engine and Cherry (aka spoonapult)
PostPosted: Wed Feb 18, 2009 4:55 pm 
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Sounds like we'd need to take care to make it right, then.
Another thought: Once built, the spoonapult would need to live someplace. (in storage)

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 Post subject: Re: Siege Engine and Cherry (aka spoonapult)
PostPosted: Wed Feb 18, 2009 5:02 pm 
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well, if it's backseat portable, i do have room in the garage.

figure ~6" cherries will be maybe 5' total for the whole shebang. wouldnt' be more than ~3' wide.

this is probably a multi day process....

anyone *built* a catapult before? i've only done a ballista and a few trebucets.


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 Post subject: Re: Siege Engine and Cherry (aka spoonapult)
PostPosted: Wed Feb 18, 2009 5:05 pm 
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Maybe a desktop sized prototype is in order, wait I think I just got an idea for a kit.

http://www.catapultkits.com/10901

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 Post subject: Re: Siege Engine and Cherry (aka spoonapult)
PostPosted: Wed Feb 18, 2009 5:06 pm 
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I'm printing out plans from:

http://www.open2.net/diyscience/mangone ... wnload.pdf

We can look at it tonight.


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