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  1. #1
    MacEntyre's Avatar
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    X Tensegrity Hammock STand

    Introducing the X Tensegrity Hammock Stand, with a supporting appearance by the Molly Mac Gear Survival Hammock.



    In which we go to Trail Days and demonstrate a hammock stand using the original X Tensegrity from Snelson, the NC sculptor who inspired Buckminster Fuller to investigate tensegrity structures. This hammock stand cures the problems that plagued our earlier efforts. The last tensegrity hammock stand that we demonstrated failed due to the asymmetrical load. In this new hammock stand, we solved that problem by binding the struts together so they can help support each other, and no single strut bears a load by itself.

    Soon, we will construct a new version of the Tensegrity Hammock Stand for Three Hammocks using this new technique.

    Enjoy!

    - MacEntyre
    "We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin
    www.MollyMacGear.com

  2. #2
    Senior Member lazy river road's Avatar
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    Awesome vid. Mac. Really informative and always love the ideas you come up with. I wish I would of seen this in person at TD. Now here is my ?. What are the chances or possibilities that a tensegrity stand could be made with folding poles with a hinge in the middle. If the poles were 9 to 10 ft long and could fold in the middle with a locking hinge then it would make a perfect stand for bringing along for car camping to a campsite where trees might be limited and one has to hang over a designated spot. I have no clue what kind of or lack there of support would provide with a hinge in the middle off the pole but man that would be cool. Thanks for the vid. Mac.
    Sometimes I like to hike and think, And sometimes I just like to hike.

    Hiking is'ent about waiting for the storm to pass its about learning to hike in the rain.

  3. #3
    Detail Man's Avatar
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    LRR, hinged poles won't work. The loading is such that the center of the strut is where failure will first occur. The last failure Mac refers to had two piece struts that joined in the middle, and was the location of the failure.

  4. #4
    Senior Member peteypk's Avatar
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    very very clever!

    while I understand that the integrity of your structure is ingeniously, yet critically dependent on load balance, I'm with @lazy river road in wanting some sort of portability option. such the conundrum to create a getup that finds the sweet spot within the strength vs. weight vs. compactness vs. height vs. cost factors.

  5. #5
    MacEntyre's Avatar
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    Quote Originally Posted by lazy river road View Post
    What are the chances or possibilities that a tensegrity stand could be made with folding poles with a hinge in the middle...? ... man that would be cool. Thanks for the vid. Mac.
    You are entyrely welcome!

    My next one will use 9' sectional poles. I'm working on it!
    Quote Originally Posted by Detail Man View Post
    The last failure Mac refers to had two piece struts that joined in the middle, and was the location of the failure.
    Au contraire, DM... they were three section poles, and the failure was in the middle of one section, between two unions. It was due to bending, from the asymmetrical load. I plan to put together that very same tensegrity, with the poles bound together, to show that the key is to have each pole buttress the others.
    Quote Originally Posted by peteypk View Post
    I'm with @lazy river road in wanting some sort of portability option.
    Absolutely! I'm working on it!

    First I will use the sectional mil surplus poles I have on hand. They will work fine for car camping. Then, I will develop a lighter sectional pole, aiming toward something that can be carried.

    I'm also going to put color coded rings on all the ends, so there are no lines to connect, just rings with the lines already on them.

    Lastly, I will either replace the fence winder with a ratchet winch, or use something even simpler. The Bob Dustrade folding saw comes to mind...

    Thanks for the kind words!

    - MacEntyre
    "We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin
    www.MollyMacGear.com

  6. #6
    WV's Avatar
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    Quite a collection of testers at Trail Days, Mac. Considerable idea-power there. Did you learn a lot?

  7. #7
    Rikall's Avatar
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    Nice work MacEntyre.

    I came up with the same design about 12 months ago and made it on a small scale with some dowel and some cord. It was a pain in the butt to get it all together and I figured that it wasn't going to be practical based on the problems I had getting the pole lengths right and getting the tension where it needs to be to support a reasonable weight.

    It is great to see that you managed to overcome these problems and create a working stand. Well done!

  8. #8
    Senior Member Wise Old Owl's Avatar
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    Why would a sleave of aluminum say 6" and brazed so one half slides into another?
    There was an Old Man with a owl,
    Who continued to bother and howl;
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    Which refreshed that Old Man and his owl
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  9. #9
    MacEntyre's Avatar
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    Quote Originally Posted by WV View Post
    Quite a collection of testers at Trail Days, Mac. Considerable idea-power there. Did you learn a lot?
    Yep! Someone suggested a hard joint device, but TZ nixed it because it would create a hot spot for failure. The best idea was from LDCakes, who suggested adding two pockets to the Survival Hammock! Dutch did not say much...

    Quote Originally Posted by Rikall View Post
    I came up with the same design about 12 months ago and made it on a small scale with some dowel and some cord.
    How about that! That's right after I realized the X Tensegrity could be tilted like a jack and used to support a single hammock! It has taken me a while to get around to making it...
    Quote Originally Posted by Rikall View Post
    It was a pain in the butt to get it all together...
    That's an attribute of tensegrity structures.

    Quote Originally Posted by Rikall View Post
    I figured that it wasn't going to be practical based on the problems I had getting the pole lengths right and getting the tension where it needs to be to support a reasonable weight.
    Making it practical is a huge challenge. It will never be idiot proof. When I realized that rings would work for attaching the tendons, the IQ required to assemble one fell considerably!

    Quote Originally Posted by Rikall View Post
    It is great to see that you managed to overcome these problems and create a working stand. Well done!
    Thank you very much! The key is to bind the crossings. That way the struts that have a bending moment, from directly carrying the load, are reinforced by the other struts.

    Quote Originally Posted by Wise Old Owl View Post
    Why would a sleave of aluminum say 6" and brazed so one half slides into another?
    Yes, unions are no trouble. I prefer inside joints.
    "We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin
    www.MollyMacGear.com

  10. #10
    richtorfla's Avatar
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    Really nice job figuring this thing out. Nice and compact. Interseted in seeing one at the 9 foot sections. So I have to ask: what is the set up time the way it is now and how is it going to be when you use the rings? I like how you figured out the ratcheting system. Like I said Nice Job!

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