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  1. #1
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    My first DIY bridge hammock

    So it has begun... I've got the DIY bug, my first thread injector, and a pile of raw materials.

    I recently purchased a JRB bridge hammock and slept in it for about a week. It's a great hammock, but I wanted to fiddle around with the design (longer spreader bars, different cut, different end caps, etc) but didn't want to cut up a $200 hammock, so I decided to make my own. Looked simple enough, how hard could it be? (Answer: not hard at all.) Friday I purchased my first thread injector, Saturday I made my first DIY hammock and slept in it that night. And wouldn't you know it, I woke up Sunday morning the same height off the floor as when I had gone to sleep, and with a bunch of ideas for my next version.

    First off, a big thanks to Grizz, TeeDee, and all the other folks that shared their experience. Because of your help, I didn't have to do any experimenting and I was able to make a good prototype on the first try. I still have some fine tuning to do, but thankfully the materials are fairly cheap, and it doesn't take long to sew one up, so I'll probably end up with a few prototypes before I pick a winner.

    My main inspiration for making my own hammock was that I wanted something a bit wider than the JRB (I'm a big guy and roll around at night, so I could use some extra space). Also, I had some ideas for a zipperless bug net and wanted to make some on-board storage under the suspension triangle, like the Eureka Chrysalis. I also had the idea to using one piece of fabric for everything and save myself some sewing. This also meant that I didn't have to mess around with creating end caps, which look like they require a certain amount of accuracy and planning, two things I haven't developed yet. The storage areas (or "canoe ends" as I call them) are quite large if you just fold the material in half, so I sewed it at an angle and then folded in a bit to create a flat bottom, which you can see in the pictures.

    The local fabric store (yes, there's just one) didn't have any appropriate materials, so I had to improvise. At Walmart, I found a "sunwall" made by Coleman for their 12x12 canopy that is basically a 6'x12' sheet of some kind of fabric. I don't know what it is, but it seems OK as a hammock material. It's not waterproof or a vapor barrier, it seems to be holding, and doesn't seem to stretch much. It's about 3 oz/sq yd, but I'm a car camper, so weight is not a priority for me. I also improvised the side suspension: ratchet straps for the webbing, eye-bolts for the rings, and PVC spreader bars. One note, my weight is enough to cause the 3/4" PVC to flex slightly, and while it seems OK for now, I'm worried that it will continue to deform under extended use, so will switch to wood dowels on future versions.

    The finished dimensions (at the moment) are:
    Length between spreader bars: 72"
    Width: 50"
    Spreader bars: 36"
    Center width: 36"
    Cut: 7" (made a nice little excel spreadsheet to calculate the parabola)

    So here it is hanging in my back yard, not bad for a few hour's work.


    Detail of the "canoe end", you can see how I folded in the material, and how the suspension runs through a channel. Future versions will probably have the straps run all the way to the end.


    Detail of the suspension/spreader bar connection, I got the idea from a tent I had when I was a kid. I also have a 2x2 spreader bar that I drilled a few holes in, and I can adjust the length of the bar by sticking the eye bolt in different holes.



    Interesting anecdote: I remember doing some arts 'n' crafts on my Mom's sewing machine as a kid, and even though I haven't touched it in 20 years, I still have muscle memory and keep reaching for the presser foot lever in the wrong spot. (After browsing Google images, I found out it was a Singer 503, I have no idea whatever happened to it.)

  2. #2
    Senior Member mbcruzin's Avatar
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    Very nice hammock. Can you give me a link to the spreadsheet?
    Life looks better from a BIAS hammock.

  3. #3
    Senior Member BrianWillan's Avatar
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    Good job on your bridge hammock. Here is more proof that doing a bridge hammock is not that hard for the newbie gear maker.

    Cheers

    Brian
    Good judgment comes from experience, and often experience comes from bad judgment. - Unknown

  4. #4
    Senior Member Oper8or's Avatar
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    Very nice hammock man! That is a slick idea. I may just have to try that.
    I am me and no one else can be me without my permission.

    My Youtube page.

  5. #5
    Senior Member raiffnuke's Avatar
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    Nice looking hammock!

  6. #6
    New Member
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    Quote Originally Posted by mbcruzin View Post
    Very nice hammock. Can you give me a link to the spreadsheet?
    I used a parabolic curve, and while it's not the cat curve, it's close enough for me, and easier to work with.

    Here's the spreadsheet I made, I've never used Google Docs, so hopefully the formulas will survive.
    https://docs.google.com/open?id=0BzY...WFBd01QV0d1NEE

    If not, the formula is:

    y = D*(1-4(x/L)^2)

    where:
    D = Cut depth
    L = Length between spreader bars
    x = Distance from center
    y = Cut depth at this location

    To double check your work, you should get y=D at x=0, and y=0 at x=(L/2).

  7. #7
    New Member
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    So now a question about structural integrity of fabric:

    I noticed that the fabric appears to be trying to pull itself apart:

    You can see how each stitch is pulling apart the weave, leaving only the vertical strands to support my weight.
    But after thinking about it, isn't that how it normally works anyways? Should I be worried? Is there some way to reinforce this? It's only a prototype, and my next version will be double layer, so I'm just curious for future reference.

    At first I did not have the bottom row of stitches, and when I tested the hammock, the strap tried to fold in half, as all my weight was supported by the straight row in the middle of the strap. I added this last row of stitching because I wanted to engage the entire strap, but I guess I didn't pull the material tight enough and this is just evidence of it taking up the slack and engaging both rows of stitches. Next time I'll use much finer stitches (probably a straight row right next to the edge) so the stress is more evenly distributed instead of being concentrated at individual points.

  8. #8
    Senior Member gargoyle's Avatar
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    Zig zag is a poor choice. But its a little late now.
    ZZ allows for the material to flex because of the wider pattern vs a straight stitch.
    You may be able to add a row or two of straight stitch to help stabilize what fabric you have left. But with the zz stitch already zippering (the dotted holes in your pic) the fabric, it might a mute point.
    Keep the stitches in the webbing (3/8" or so) and not on the edge, this allows the two pieces of fabric to share the load.

    Some fabrics perform better for weight support. Not sure how well the sun panel will do??

  9. #9
    Senior Member more's Avatar
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    Huh. My BMBH looks exactly like this when I'm hanging in it.
    My Flickr photos Outdoors collection

  10. #10
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    Quote Originally Posted by gargoyle View Post
    Zig zag is a poor choice. But its a little late now.
    ZZ allows for the material to flex because of the wider pattern vs a straight stitch.
    You may be able to add a row or two of straight stitch to help stabilize what fabric you have left. But with the zz stitch already zippering (the dotted holes in your pic) the fabric, it might a mute point.
    Keep the stitches in the webbing (3/8" or so) and not on the edge, this allows the two pieces of fabric to share the load.

    Some fabrics perform better for weight support. Not sure how well the sun panel will do??
    Thanks for the insight, I hadn't seen anything explaining the difference between various stitches, or what to use where, so I guessed. Thankfully it is just an experiment and will be soon replaced with version 2.

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