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  1. #1
    Senior Member SteelToe's Avatar
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    Lightbulb UCH Version 2.0 Prototype Hammock Mockup

    That's "Unnecessarily Complicated Hammock," and I've finally got the initial setup pinned together for test fitting and reinforcement. It at least looks a lot cooler than the first prototype

    I'm an engineer, by trade, so generally I hate unecessarily complicated designs. But as a home-tinkerer, I find them an endless source of amusement . I came up with this idea a couple years ago, and even made an initial prototype when I was getting out of college, but got distracted for a few years . The idea is to get a hammock with two support points to approximate the "lay" of a Lay-z-boy recliner

    Prototype 1


    The first design was totally functional, and comfortable once inside. But, it was too snug in the shoulder openings, which made getting in/out a bit of a gymnastics challenge; you can only get out by doing a sit up while pulling your arms back . This time, I left the shoulder-relief cutouts much larger and I''ve incorporated a "bottom entry" type opening that doubles as a support for the seperate foot/leg boxes. I also reworked the suspension/load paths a bunch from the original design (which was basically a convoluted bridge hammock). Before, the tension supporting the upper spine went right through the "head basket" to the support cables, and squeezed my head annoyingly.

    Now, one load path goes from the support point, along the spine, splits at the torso, and ends at the support cables on either side of the waist. Meanwhile, another load path starts at the other support point, splits just before the inseam (at the doorway), and ends at the support cables above the user's armpits. The place where these two paths cross forms a diamond shape beneath the torso, which should dissipate the load enough that the user won't feel like they're sleeping on a rope bridge . Complicated to describe, but I'll be reinforcing these high-stress load paths with webbing (once my order arrives) that will really make it obvious how the weight is carried .

    Prototype 2

    It's cold outside, so no, I'm not doing this on my patio, now . I apologize for the black-on-black color scheme of the hammock and dummy, which makes things less clear than they could be

    It's kinda creepy, but the mannequin is a reasonably accurate form, being made of laundry stuffed into other laundry (), and gives a decent idea of how the lay is supposed to work. The user is supported by panels at the torso (just below shoulders), waist, thigh, and calves (heels and head, too, but the model doesn't have these yet). Between these areas, there is no support pressing on the user (joints, small of back, shoulders). Two cables/straps pulling up below the inseam (not at the inseam ) to the ridgeline serve to separate the legs and knees, and make for an easy/fast doorway to roll forward through (sort of like a vertical Hennessey door).

    Right now, the shoulder-blades are painfully unsupported, but there will ultimately be two stirrups riding "sidecar" for the user to lay their arms in, taking most of the load off the shoulders. Some taut, stretchy fabric gussets beneath the shoulder blades themselves should then be able to support them comfortably, without sucking in tension from adjacent load paths.


    I have the doorway held open with a pencil in this shot--you can see how it is tensioned closed by the user's weight

    The purpose of the mannequin, for now, is to simply check that load is concentrating where I expected it, and to adjust shapes and angles to get what I'm looking for. So far it looks fairly good, but I think I'll have to rework the panel that supports the waist, as I'd expected, since I don't think it's wide enough (no jokes, now ) for my keester. There is a lot going on at that panel (splits and joins door opening, while carrying a lot of load), so I could only make a rough guess at what shape was needed. Another 2" or so of "web" and it should be perfect. The head and foot holsters are fairly straight forward, so I'll fit them last once the rest is finished enough for me to lay on (read: not held together with pins and twine )

    I'll update this thread as I get everything attached to real suspension lines (and I become the test pilot ). If I don't get dumped on my rear, and the hammock appears to function as intended, I'll put up the patterns for the various shapes that make up the design, in case anyone else wants to practice putting grosgrain on convoluted edges. So far, construction hasn't been harder than my two Hex-Cat tarps, because all fabric pieces are so small and easy to work with.

    TCB
    (Okay, I must confess the amount of "engineering" in the design so far is something of a myth. At this point it's mostly a geometry experiment since I don't really know how strong the Joann's fabric I'm using is; some kind of light polyester taffeta called "silkessence")
    Last edited by SteelToe; 01-03-2013 at 23:19.
    www.hammockforums.net --I get it!

  2. #2
    Senior Member Brute1100's Avatar
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    Tagged to follow the insanity!!! Looks awesome, hammock of the future!!!
    Live, Laugh, Love, if that doesn't work. Load, Aim and Fire, repeat as necessary...

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  3. #3
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    I'm guessing your speed of progress on this "outside the box" project would increase dramatically if you got a new partner. The one you have now seems to be such a stuffed shirt.

    Looking forward to future installments.

  4. #4
    Senior Member Fish<><'s Avatar
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    Also subbing into the insanity. I am not an engineer, so any paper I can cheat off of in class, I will. Thanks for posting and I look forward to future developments.
    "We do not go to the green woods and crystal waters to rough it, we go to smooth it."- G. W. Sears

    My forum name is Fish<><; I'm in the navy; and I hate sleeping on the ground. If I didn't need ground to walk on or measure resistance to, I think I could happily give it up.

  5. #5
    Senior Member SteelToe's Avatar
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    It...could...work!!!



    With some great input from folks here, the suspension loop at the head end of the floor* is on and is stronger than Zeus--no worries there. I tied off the tail-end straps (which are 11ft long since I haven't cut them) to the hammock stand, and added a continuous loop which I threaded through the edge channels of the torso section of the hammock. I then carefully...carefully... ...carefully laid my weight down into it (over a pilow ) and... ...stayed aloft!!

    Comfortably, in fact . Aside from an obvious lack of support for the arms and legs for the time being, there were no hard or pinch points to speak of. I'll have to toy with the suspension geometry as I go since the lay isn't where it needs to be just yet, but progress is finally tangible. I'll have an even better idea of where the utility of this setup stands once I get the thigh support/doorway panels attached.

    After those are attached the hard part is going to be nailing down the suspension shape. Everything is adjustable right now, so I'm not sure where to being fixing lengths. My game plan for now is to get a comfortable position with as little tension as possible, but that still holds me off the ground in my 12ft steel hammock stand. The theory is that such a setup will be very compact, and will allow for extensive indoor testing during the hot Texas summer

    Oh, I've attached a shot of the "concept drawing" I've been working towards. I think I drew that about two years ago . In the top view, the cross-marked lines indicate the webbing sewn into the floor that carries most of the load. As you can see, it's roughly a diamond shape, with the small of the back near the middle. Two of the diamond "points" are at the head and inseam, and will be attached to the ridgeline.

    TCB

    *Amsteel Experts' Advice Needed!
    Attached Images Attached Images
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  6. #6
    Senior Member SteelToe's Avatar
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    Alright, finally some pictures!

    Progress update:

    The major suspension elements are done, and the major fabric panels are fully installed. I can lay in the thing almost comfortably, and now need to focus on getting the arm slings and foot pockets attached so I can lay in the thing truly comfortably. I also need to work on finishing the entryway closure. I will try adding a spreader bar at the shoulders eventually, though it is not needed for anything other than making entry/exit easier. The head basket will go on soon as well, though resting my head on the narrow end of the strap is comfortable (though not very stable )

    Right now, it's a skeleton that has proven out the concept (to me, at least). I've tried to take some pictures that demonstrate how everything works, hopefully clearer than I've been able to describe in the past.

    But first, because all this is worthless without proof



    The suspension works as a hybrid between a gathered-end and a bridge hammock. Two rails carry the sides of the user, and keep them from rolling out side to side as in a bridge hammock. But cables pulling down the length of the floor at the spine support some of the user's weight as well, as in a gathered end. The combination of both these suspensions allows for a flat lay (as in a bridge) with little to no squeeze (as in a gathered end). The "rails" are at a fixed length, and (for now) all lay adjustment is done with the ridgeline and Shear line. The shear line is what keeps the cable loop running from spine, to ridgeline, to inseam from sliding the center of mass towards the middle. It also pulls up on the straps between the legs, keeping them from rolling inward uncomfortably. Because Amsteel is so rigid, very small (1") changes to the shear strap have huge impact on the angle your upper back lays at, and the delicate balance between too much squeeze, and too much floor tension (feels like lying on top of Snoopy's doghouse )


    View from the head position showing the entry way (spread open by a white thimble for visibility). It's like a Hennessey door, only elevated, with the legs resting on either side.


    A look at the back rest. This area tapers inward from the rails just after the points of the hips, but below the ribs, so there is little to no squeeze from the edge of the fabric (there is a little squeeze at present because I cut the catenary here too shallow, but it will be cut back if it comes to bother me).


    You can also see where the floor splits at the entry way, and how the legs would continue to lay horizontally on either side. The split occurs about 5" below the inseam, so there is no "wedgie." This is the most complicated area on the hammock, mostly because of poor planning and prototype improvisation on my part. There was originally a gap between the two panels, but that was barely too long for my torso. Were I to do this again, I would also lay the two straps that form the split atop eachother, instead of placing them side-by-side. Because I couldn't bar tack them to keep the door from tearing at the corner, I had to sew in a 2" piece of webbing between them to carry the tension. For reference, the point of the user's hips sit where the two webbing straps cross halfway down the sides of the larger panel (you can see the stitching if you look close)

    Here's a picture of the outside of the hammock when loaded (pardon my keester) showing the load-carrying straps beneath the torso section. They cross on both sides and meet at the ends of the floor, forming the platform you sit in. The sides of the diamond are supported by the rails, and the ends by the ends of the ridgeline. You can also see how flat the lay is. My upper body is at more of an incline, which I find comfortable.



    Next Steps (so I can keep track of them):
    1) Attach foot rests, so I can finish nailing down the lay for the legs
    2) Attach arm rests, to determine if I'll be needing some support behind the shoulder blades after all
    3) Attach head basket, so I can try sleeping in it, and see if a spreader bar makes it easier to lay back into
    4) Settle on a shear line configuration, and sew it in place (currently basted in place). At this point, attach ridgeline to rings via larksheads so it can no longer slide, and to fix structural ridgeline length.
    5) Attach panels enclosing entryway
    6) Outdoor testing with my Hex-Cat tarp to see if it can be used (fingers crossed)
    7) Figure out how I want to enclose the hammock with netting or insulation
    8) Enclose hammock with netting and insulation (I'm sure it'll be a snap )

    Hopefully I can have this thing ready and tested by my trip in the Maroon Bells of Colorado. Fortunately, these late snowfalls mean the passes won't open until August (or next year! )

    TCB
    www.hammockforums.net --I get it!

  7. #7
    Member kafer4life's Avatar
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    Looks like a fun project, thanks for sharing.
    The Sluggard's craving will be the death of him, for his hands refuse to work.

  8. #8
    Senior Member Rikall's Avatar
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    I love the concept. Excited to see where this goes.

  9. #9
    Senior Member SteelToe's Avatar
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    Got the calf supports reworked, so I've basically finished the main structural portion of this project. I think I figured out how I'll do the arm rests. I'll have two wide straps (slings) wrapping around (loosely) from behind the shoulder blades to the rails above the waist. This will function like a shoulder-sling to support the elbows, and keep the forearm against the body (wrists over the navel) which should be very comfortable when it's cold and I have insulation on the hammock.

    A second strap will split off at the elbow and attach to the rails further down, which will allow my arms to lie more horizontally, and away from my body somewhat--much better when I'm trying to stay cool in the summer with only a bug net.

    I am still undecided how I want to go about enclosing the hammock. My original thought was to use mesh/loose knit fabric to close out all the openings, but I'm starting to wonder if I should leave everything open, and have the detachable nets/quilts close the openings instead--seems like that could be lighter. The taffeta-stuff ("silkessence" ) the hammock is made of is nowhere near mosquito proof (and I don't want to test that theory), so a wraparound net will be needed regardless.

    Unless they prove as elusive to nail down comfortably as the leg supports, the arm slings should go on quickly tomorrow, and I can move onto the head basket (I'm contemplating a minor change to that design as well which will be less confining). I'm making okay progress, I'd hoped to have the hammock body done by the 1st and be working on a quilt by now, but I'm not doing too bad at a week behind.

    TCB
    www.hammockforums.net --I get it!

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