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  1. #1
    Member Leifo5343's Avatar
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    Hiking pole spreader bar failure.

    So, the pole snapped under the compression. I thought it would be okay because I saw others doing the same.

    I was thinking of using a dowel or something. I've spent the last 5 hours scouring all the threads I could and I have seen dozens of ideas floating around, but I'll just come out and say it.... what is a best, light, surefire way to not have it break on me again. The hammock is Grizz's DIY Bridge.

    Oh, and I ordered this tarp today. I think I might have screwed myself over, but I'm a student, and I'm poor (funny how those both coincide). http://www.amazon.com/gp/product/B00..._ya_oh_product

    Thanks for the help.
    "The nuclear generator of brain sludge is television." By Dave Barry

  2. #2
    Senior Member
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    I'm bumping this so that someone with more engineering experience can chime in. My only thought: there is no way that the spreader bar wasn't exactly perpendicular to the hang of the hammock, was there? Also, it's hard to resist temptation, but the poles shouldn't be used as pull-up bars to adjust your position within the hammock. I've seen some poles with offset handles - it seems like the force of a load could bend those outward.

    I've never seen any stress in my poles, but they are old clunky things. What material was the pole that broke?

  3. #3
    GrizzlyAdams's Avatar
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    well huh. I wrote out a reply this morning but I guess I hadn't had my cupa strong tea yet because it seems I missed pushing "submit" or something.

    Well then, first, sorry about that pole. You don't give any other information about your setup so I'll just run down the important things.

    1. Really important to keep the forces focused down the center of the pole. That can be a little tricky, but a number of folks have pulled that off in various ways. It is nearly impossible if the pole handle is a sort of bent thing like they often are.

    2. I would not use a carbon pole. From what I've read they have considerably less strength in the lateral direction than an aluminum tube. That means that the smallest deviation from having the force centered will stress the pole where you don't want it stressed.

    3. The length of one side of your suspension triangle should be at least 75% the length of the spreader bar. I normally have it as long as I can and still have all of both triangles under a tarp with an 11' length, which means for me 30-32 inches for a 36 inch spreader bar...more like 85%.

    Grizz

  4. #4
    GrizzlyAdams's Avatar
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    Quote Originally Posted by vitamaltz View Post
    ...Also, it's hard to resist temptation, but the poles shouldn't be used as pull-up bars to adjust your position within the hammock. ...
    Forgot this one, it's good. Grab the middle of those bars and pull yourself along, well the main direction you'll go is down 'cause that pole is history. You're directing all that force to deliberately go off center. Power of physics takes over.

    Grizz

  5. #5
    Member Leifo5343's Avatar
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    Hey,

    I would not use a carbon pole.
    The trekking poles I used were aluminum. When I got in the hammock for the first time, the pole bowed out and snapped the tip right off.

    The length of one side of your suspension triangle should be at least 75% the length of the spreader bar.
    I have my length of the triangle at 28" and the spreader bar at 36" just like your tutorial said. Oh well. I decided to get a couple 32" pieces of metal conduit and use those as spreader bars. They aren't light, but they are sure strong. Grizz, the rest of the hammock is built using your specs for an 80" hammock. That's the info on the hammock.

    I haven't tested it yet, but I will as soon as I can.

    Thanks!
    "The nuclear generator of brain sludge is television." By Dave Barry

  6. #6
    GrizzlyAdams's Avatar
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    Quote Originally Posted by Leifo5343 View Post
    Hey,



    The trekking poles I used were aluminum. When I got in the hammock for the first time, the pole bowed out and snapped the tip right off.



    I have my length of the triangle at 28" and the spreader bar at 36" just like your tutorial said.
    28/36 = 77.77%, so there you're good.

    Dowel rods in the pole help.

    Gotta have the force centered.

    With these specs I've used 1/2" ID PVC pipe with oak dowel rod
    inserts and had it work. PVC is surely more susceptible to bending
    than aluminum.

    Gotta have the force centered.

    there's an echo in here.

    Oh well. I decided to get a couple 32" pieces of metal conduit and use those as spreader bars. They aren't light, but they are sure strong. Grizz, the rest of the hammock is built using your specs for an 80" hammock.
    I haven't tested it yet, but I will as soon as I can.

    Thanks!
    good luck...

    Grizz

  7. #7
    Senior Member pisanodc's Avatar
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    Anyone have any luck using a trekking pole for their jacks r better bmbh spreader bar? If so, how'd ya do it?

    Thx,
    pisanodc

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