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  1. #1
    Senior Member Albert Skye's Avatar
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    Question destructive testing

    It seems useful to do some destructive testing. As I understand it, Dyneema/Spectra (Amsteel) cordage is proportionally weakened by knots (loaded bends) much more than is nylon, for instance.

    Some forum members appear to have lots of cordage and the inclination to sacrifice it for experiments, so I offer the suggestion to perform some tests (which I'm not prepared to do myself).

    Obviously, very strong anchors are necessary. Pulleys can be used to multiply forces and water can be used to apply a measured load. I suggest testing the Garda hitch and the marlinspike hitch (especially with small-diameter pins), because those are so popular.

    It should also prove interesting to test D:d strength, if nothing else, and discover how much the plot differs from that for wire rope.
    Last edited by Albert Skye; 11-25-2009 at 14:16. Reason: added link about mechanical advantage of pulleys

  2. #2
    Running Feather's Avatar
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    There is a lot to digest here. Very interesting.
    "If you find yourself in a hole, the first thing you should do is STOP DIGGING "

  3. #3
    Knotty's Avatar
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    If I had the gear I'd give it a try, just to satisfy my curiosity. Creating the load isn't the hard part. But how do you measure the load?
    Knotty
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  4. #4
    Senior Member angrysparrow's Avatar
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    Quote Originally Posted by Knotty View Post
    But how do you measure the load?
    I think that's why he suggested using water. The weight of it is known for the given quantity you add.
    I think that when the lies are all told and forgot the truth will be there yet. It dont move about from place to place and it dont change from time to time. You cant corrupt it any more than you can salt salt. - Cormac McCarthy

  5. #5
    in it for the naps oldgringo's Avatar
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    Assuming the line will fail somewhere north of 1000#, that's a lot of water.

    Maybe some sort of rig that employs a known mechanical advantage would work.
    Dave

    http://www.uark.edu/misc/xtimber/rna/pattonsbluff.html

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  6. #6
    MacEntyre's Avatar
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    Quote Originally Posted by oldgringo View Post
    Assuming the line will fail somewhere north of 1000#, that's a lot of water.
    Only 125 gallons.

    Two 155 gal drums would probably do the trick. Each one, when full, would weigh about 1250 lbs.

    - MacEntyre
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  7. #7
    Dutch's Avatar
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    What I do is this;
    I have a pallet scale that goes 2000+ and I also have molds that are around 2000 pounds at work. So I put the mold on the scale and lift using the towmotor. If I can lift it so there is 1000 left on the scale I guess it is around 1000. I watch the scale and see when it breaks. It isn't perfect science but it is a good representation. Don't tell my employer I am lifting his $80,000 molds up by webbing and rope.

    So all you have to do is find someone with a similar set up and convince them to do it for you.
    Peace Dutch
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  8. #8
    in it for the naps oldgringo's Avatar
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    Quote Originally Posted by MacEntyre View Post
    Only 125 gallons.

    Two 155 gal drums would probably do the trick. Each one, when full, would weigh about 1250 lbs.

    - MacEntyre
    Don't guess I've ever seen 155 gal drums.
    Dave

    http://www.uark.edu/misc/xtimber/rna/pattonsbluff.html

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  9. #9
    MacEntyre's Avatar
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    Quote Originally Posted by oldgringo View Post
    Don't guess I've ever seen 155 gal drums.
    That's a test, to see if anyone reads posts with numbers in them.

    "We must, indeed, all hang together or, most assuredly, we shall all hang separately." - Ben Franklin
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  10. #10
    Senior Member JerryW's Avatar
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    Quote Originally Posted by MacEntyre View Post
    Two 155 gal drums would probably do the trick. Each one, when full, would weigh about 1250 lbs.
    - MacEntyre
    Quote Originally Posted by oldgringo View Post
    Don't guess I've ever seen 155 gal drums.
    Quote Originally Posted by MacEntyre View Post
    That's a test, to see if anyone reads posts with numbers in them.
    I was looking at your numbers, too...it would only be 1240 lbs.

    Quote Originally Posted by Dutch View Post
    What I do is this;
    I have a pallet scale that goes 2000+ and I also have molds that are around 2000 pounds at work. So I put the mold on the scale and lift using the towmotor. If I can lift it so there is 1000 left on the scale I guess it is around 1000. I watch the scale and see when it breaks. It isn't perfect science but it is a good representation. Don't tell my employer I am lifting his $80,000 molds up by webbing and rope.

    So all you have to do is find someone with a similar set up and convince them to do it for you.
    Dutch, since you already have this neat set-up...
    The "Search" function is your friend!

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