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Author Topic: Giant Bow  (Read 10112 times)

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Offline Badger

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Re: Giant Bow
« Reply #30 on: August 31, 2015, 11:00:02 am »
  Actually the amount of " give " in the bow was just about right. If it had more give it would have been too weak. The drum in the middle only needed to make 1/2 revolution with about 1/4 revolution preload. As the project progressed we actually imagined several configurations on the same principle that could have been really effective. I think back in Da Vincis day they would have done it the same way, start off with one project in mind and then modify it accordingly. We were not allowed to modify, it had to look just like DaVinci drew it on his plans.
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Offline DC

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Re: Giant Bow
« Reply #31 on: August 31, 2015, 12:53:16 pm »
I think these things were just Leonardo's doodling. Keeping his mind busy. He's my hero, has been since I was a kid. :) I was so exited when that show first came on(it was a series) and those boneheads screwed it up with their bickering. There was another show the BBC did called "Rough Science" that had 4 or 5 people working on a project. They got along great and the show flowed smoothly. But producers seem to think they need drama.
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Offline Ranasp

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Re: Giant Bow
« Reply #32 on: August 31, 2015, 01:10:30 pm »
Sorry, I didn't mean give in the bow, that part looked perfect, what I meant was give in the arm stop.  First there was no stop at all so the arm smashed, then they use a rope that yanks the arm abruptly at the end and it winds up cracking just above where it's tied on.  Maybe that was just bad luck or a hidden flaw in the wood...
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Offline Badger

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Re: Giant Bow
« Reply #33 on: August 31, 2015, 03:03:44 pm »
  I agree with you on that sudden stop, I had calculated the g forces of acceleration with a 5# weight on the end of the rod and built it to just flex with that much force on it. Comming to a sudden stop had far too many g's for it to survive. I warned them about it.
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Offline lebhuntfish

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Re: Giant Bow
« Reply #34 on: August 31, 2015, 03:27:43 pm »
So that's why you brought in the shorter, more sturdy arm. It's funny how people that think they are smart don't know very much.

I think it would be cool to build that thing on its side and see how far the bow it's self would fling a projectial! Patrick
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Once an Eagle Scout, always an Eagle Scout!

Missouri, where all the best wood is! Well maybe not the straightest!

Building a bow has been the most rewarding, peaceful, and frustrating things I have ever made with my own two hands!

Offline sleek

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Re: Giant Bow
« Reply #35 on: August 31, 2015, 03:32:00 pm »
The original compound bow.... it has all the elements,  just in the wrong order. Kinda like a Picasso. 
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Offline Badger

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Re: Giant Bow
« Reply #36 on: August 31, 2015, 04:25:29 pm »
  The thing that bugged me the most about the build was the lack of communication with the engineer. If I asked him a question I never got anything in the way of an answer, I had to go over to the machine and try to figure out what they were doing in the way of gears and such. I did make them rebuild the big steel gear so it would detach from the drum after winding up the bow. Getting that big flywheel spinning would have robbed all the  power. That arguement got a little heated, I guess the language involved wouldn't work for TV.
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Offline Ranasp

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Re: Giant Bow
« Reply #37 on: August 31, 2015, 05:21:44 pm »
Quote from: lebhuntfish on August 31, 2015, 03:27:43 pm

I think it would be cool to build that thing on its side and see how far the bow it's self would fling a projectial! Patrick

   On PBS they showed a special called "Leonardo's Dream Machines" that had two different teams, one building a ballista and another an airglider based off of sketches Leonardo did.  Trailer can be viewed here: https://www.youtube.com/watch?v=6y4bgibiRdg

Badger, I would have loved to see THAT debate (argument) rather than the silly post-it note nonsense.  Also think it would have been awesome if you could have gotten in on the ballista building.  The Dream Machines makers seemed to be a lot more concerned with authentic period technology with no spot welding or modern glues used. 
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Offline lebhuntfish

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Re: Giant Bow
« Reply #38 on: August 31, 2015, 06:10:06 pm »

  The thing that bugged me the most about the build was the lack of communication with the engineer. If I asked him a question I never got anything in the way of an answer, I had to go over to the machine and try to figure out what they were doing in the way of gears and such. I did make them rebuild the big steel gear so it would detach from the drum after winding up the bow. Getting that big flywheel spinning would have robbed all the  power. That arguement got a little heated, I guess the language involved wouldn't work for TV.
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Good for you bud! It almost sounds like all they wanted was a machine that looks like it would work. Then if it didn't they would of came up with something like, " DaVinci new it wouldn't work, that's why he never built one". Patrick
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Once an Eagle Scout, always an Eagle Scout!

Missouri, where all the best wood is! Well maybe not the straightest!

Building a bow has been the most rewarding, peaceful, and frustrating things I have ever made with my own two hands!
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