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  1. #1
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    Pull Testing Stitching in Webbing

    I decided to do some testing on the strength of different stitches in webbing.

    I built a simple fixture to hold the come-along, scale and test piece. The come-along is rated to 2,000 lbs and the scale is rated to 10,000 lbs and in calibration. The load was always steadily applied, not shock loaded
    Pic 1

    All the test pieces were 1.25 inch light weight polypropylene from Strapworks rated at 600 lbs. All the thread is Synthetic TEX 30, 3.5 breaking strength from Speer Hammocks. The box stitch was 1 inch square with an X in the center, 11 stitches per inch. For the bar tack I set the machine to Zig Zag, .2 inch wide and 34 stitches per inch. The box and bar tack were both double stitched. I tried a single stitch but it failed under very light loads.

    The first test was a single bar tack. It failed at a light load by the webbing pulling out of the stitching.
    Pic 2

    The second test was 2 bar tacks.
    Pic 3
    It failed at 200 lbs. Again it failed by the webbing pulling out of the stitching
    Pic 4

    The third test was 3 bar tacks.
    Pic 5
    This test the stitching held at 600 lbs.
    Pic 6
    Failure didnít occur until about 700 lbs and then it was a slow tearing of the webbing.
    Pic 7

    The box stitch held at 600 lbs.
    Pic 9
    Again the webbing failed a about 700 lbs and it was with a slow tearing of the webbing.
    Pic 10

    I now have a much more easy feeling laying in my hammock.
    Let me know what you think.

    Unknown
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  2. #2
    once again, very cool test, interesting the stitched webbing bar tack and box stitch failed at or ver the breaking strength of the webbing. just thought of something. all polypropelyene webbing i have seen is rated per inch of width. for example, 1.5" polypro rated to 500 # would really be rated to 750, due to it's extra width. ithink that would make your webbing 750# strong (if my math is right) still, failure occured at close to the limit of the webbing with both stitch patterns.

    great test.

  3. #3
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    Great test. I thought my webbing was the strongest link in my chain.
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  4. #4
    so it was the webbing that failed, not the stitches right? stronger webbing stitched the same way should take more force? is that what it seems? lots of folks use polyester b/c it is so much stronger for it's weight. avail at www.owfinc.com

    it's the 1" woodland polyester webbing, rated to 2000# do you think it would hold more than 700#?

  5. #5
    Senior Member FanaticFringer's Avatar
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    Quote Originally Posted by warbonnetguy View Post
    so it was the webbing that failed, not the stitches right? stronger webbing stitched the same way should take more force? is that what it seems? lots of folks use polyester b/c it is so much stronger for it's weight. avail at www.owfinc.com

    it's the 1" woodland polyester webbing, rated to 2000# do you think it would hold more than 700#?
    That's real nice webbing he mentioned. Been using it for awhile now. Weighs the same as Speer 1" polypropylene webbing and much stronger.
    Last edited by FanaticFringer; 02-09-2008 at 19:37.
    "Every day above ground is a good day"

  6. #6
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    Round turn and two half hitches

    I got a request from TiredFeet to test a Round turn and two half hitches knot because of it's greater strength. I was able to get to 900 lbs before failure. Again it failed with a snap and failed right at the knot.

    unknown
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  7. #7
    Senior Member TiredFeet's Avatar
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    Quote Originally Posted by unknown View Post
    I got a request from TiredFeet to test a Round turn and two half hitches knot because of it's greater strength. I was able to get to 900 lbs before failure. Again it failed with a snap and failed right at the knot.

    unknown
    Thanks - I see it did a little better than the bowline.

  8. #8
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    I cannot remember the right link, I think it was animated knots. They did a test of rope breaking strength vs the knot. To simulate the non-knot side I think they wrapped the rope around the attachment point a few times. If you try that it might take the knot out of the equation.

    In the end I think we should go back to the climbers theory that if you are worried about the rope breaking at half strength (caused by the knot), then you are not using strong enough rope.
    Is that too much to ask? Girls with frikkin' lasers on their heads?
    The hanger formly known as "hammock engineer".

  9. #9
    That's cool, but I test the traditional way: I bounce up and down in the hammock and if my I don't hit the ground, it'll do!

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