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Ultra-Light External Frame Pack


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  • #1356656
    BPL Subscriber
    Member

    @bobone

    I’d suggest you might want to skip the joint at the vertebra in the initial build, maybe building it light enough to maybe flex just a little there. This could let you try most of the concepts with little more than a layup with some padding, straps, and bag added, and a little devising to keep the packbag from flopping forward where it’s not wanted.

    My guess is that a well-fit girdle will show its fit value in this context, but that as the fit improves with the rigid structure around the hips, it will start to feel like you want that vertebra moving more in order to feel less restricted.

    A step up in complexity over a solid vertebra could be to a rubbery-resilient connector in there, with spectra limiting the crunch and de-crunch motion.

    The full complexity version could be the double-hinged structure we already discussed (the 2/3-gimballed vertebra), or the spectra-limited ball-joint version.

    #1356682
    Bill Fornshell
    BPL Member

    @bfornshell

    Locale: Southern Texas

    I enlarged the EXODUS pack pictures in the catalog on a copy machine and then scanned them. I am posting the pictures along with what MH says about each feature.
    -0-
    Mountain Hardwear EXODUS Pack Series:
    Two EXODUS Frames.
    (NOTE: Most of the following was taken from MH information.)

    1. Motive Frame:
    The Motive frame is designed for active backcountry and off-trail use. Motive’s free-floating design allows unrestricted mobility for technical activities. For use with medium loads.

    2. Cruiser Frame:
    The Cruiser frame is designed for traditional backpacking and trail-oriented use. The Cruiser’s center stay provides excellent stability and support for heavier loads.



    NOTE – (From Bill):
    1. I think the only difference between the two frames are the lower part of the frame sheet area. It looks like the lower cross piece on the Motive connects to the upper part of the frame the same way the lower part of the Cruiser does. If you had one of the frames you might be able to get the parts to change the frames from one to the other and back. That would give you one frame that could work both ways with a quick parts change.
    2. Notice the points on the far sides of the top of the frames. This is what the pack bag slips over when you put it on the frame. Straps on both sides of the bottom of the bag pull it down and the pressure holds it. The lower straps then attach to the bottom of the frame.
    3. If you could buy other size pack bags you could swap out a larger bag for a smaller bag or the other way around.
    4. I would just sew me a new SUL pack bag out of some Cuben Fiber.
    5. I weighed the Maestro – med. The frame alone was 3 pounds 12 ounces. The bag alone was just at 2 pounds. Total weight was just as MH lists it – 5 pounds 12 ounces. Being that close to a pack that was that heavy empty made my blood pressure go up.
    6. There is a lot of room to lighten the pack/frame system. I would really like to have one to put on a diet if I could get it free or at a really good discount.



    Pack Detail:

    The Mini Frame:
    This piece of molded polycarbonate is the backbone of the EXODUS system. It is engineered to have great vertical stiffness (keeping the loaded pack bag under control) while having torsional flexibility (allowing it to move with you when you twist your torso). Also built in to the Mini Frame is the ability to adjust the pack’s torso length. You can either custom-fit the length to one lockable setting or allow the adjustment to ride free so the frame can adjust to your movements on the fly.



    The U-Bar:
    The U-Bar connects the yoke of the harness to the main frame. This does two things: it holds the yoke in its correct, load-bearing shape, and it allows you to adjust the upper body-to-pack geometry. What’s more, it lets you do the adjusting on the fly.



    The Fit-Lock Harness:
    You can mold our yoke-and-belt system so that it fits the contours of your neck, collar, shoulders, hips, and waist. Then lock that fit into place. The harness stays in that setting until you decide to readjust it. High density foam and polycarbonate overlay hold this body-fitting shape, so load is transferred evenly. Think of how hard it would be to hold a cup of coffee if the handle were a floppy piece of fabric. That’s what packs with non-structural shoulder straps are asking you to do.




    Scandium Tubes:
    Heat-treated Yunan Scandium tubes attach to the Mini-Frame and transfer load to the waist belt. These advanced alloy tubes are very light and have high compression strength combined with just the right amount of flexibility to absorb a bit of shock and to allow the aforementioned torsional flex.



    The Pivoting Waist Belt:
    While wearing most packs, bending over to tie your shoes is virtually impossible. That’s because you are strapped in to a structure that does not bend where you do. Our pivoting waist belt changes that. Its two pivoting joints leave the belt free to tilt forward or back when your hips do. Now you can bend forward to tie your shoes or bend back to reach for a hand hold without having your pack fight you all the way.


    #1356690
    BPL Subscriber
    Member

    @bobone

    Thanks Bill…I can see a lot better on those pics.

    Looks like you ran the wands farther forward on your “clone”, right? It looks to me from the pictures like the MH would be more out of the way, behind the hips, but would primarily not provide as much triangulation. It also looks like the MH packs would be prone to pulling backwards at the shoulders and would be suited only to moderate loads…which is fine, but not at the weight of those packs. For that sort of weight it seems to me that one ought to be able to easily get the benefits of a metal external frame with at least semi-cantilevered wings to keep the pack from pulling backwards as much. My Stephenson with large bag runs 54oz. vs. the 92oz of the big MH pack. The Stephenson gets by nicely with those ephemeral mesh shoulder pieces due to the lack of backwards pull, and doesn’t require the giant puffy insulated girdle of the MH.

    Seems to me there’s merit for parts of the MH design, but that the layout is really best for fairly light loads in a situation where it’s desirable to maintain lots of flexibility, but it seems that for that usage, a pack ought to weigh a whole lot less. That also looks like quite a hot pack to wear.

    I’m curious about how light a load a modern external frame might be ideal for with on-trail use. Someone recently reported on this thread that they were experimenting successfully with externals for quite light loads, if I recall correctly. It seems to me that if one even just built on the Stephenson pattern with CF and Cuben but for the same load capacity, the pack would weigh quite a bit less than the Stephenson. If the structure were optimized to take advantage of the ability of CF layups to run where they need to rather than where fairly simple ladder construction with tubes dictates, a lighter pack should result.

    If such a pack was then built to only handle lighter loads than the Stephenson is capable of, the resultant pack should be lighter still, and we might then find out at what minimum pack-contents weight (how many days’ on-trail range) the external might become preferable to the simple SUL packbag.

    #1356692
    Bill Fornshell
    BPL Member

    @bfornshell

    Locale: Southern Texas

    The “wands” on the “clone” were to close to my body and I removed them. My Wands also were to stiff to bend – they had almost no flex. One of the changes I have made on that frame has been to use a longer “frame sheet” thing. I know a lot more now than I did when I made it and I think if I made another one I would make a lot of changes. If I made it wider at the top I might have space for the wands. If I can find something that will flex like MH uses I would try that. Now that I know what the MH wands are made out of I discovered that they also use that same stuff for some of their tent poles. I am going to call monday and ask about buying a set of tent poles if any are long enough to work on the frame.

    If all the Exodus packs had not been recalled I would have been able to get more pictures and would have had time to study the pack at the local store here a lot more. I will check back with them and see if they are going to get them back when the problem is fixed. The packs are very heavy and I am sure they would be very hot in warm weather. The fittings are all 1″ or bigger and there are a bunch of them. The hip belt webbing is 2″ and the buckle for it is a monster. Lots of places to drop some weight. The hip belt is thick and heavy and the shoulder straps could be also lighter. I was shocked at how heavy the frame was when we took the bag off of it.

    I have learned a lot just by enlarging the pictures and typing the data about each picture. I also think there are parts of the frame that might work on what we are after. For me this last week has all been a lot like Frame Design 101. It was nice of MH to go into so much detail and all your input has also taught me a lot. Dale, you fit in here also even if you forgot about my Cuben Water Filter.

    I have made an external frame (stripped) as light under 7 oz that was full size and my Cuben pack bag for it was only 2.10 ounces. 1.28 ounces on that pack bag was for the full side and front mesh pockets. The pack bag is a little larger than the G6. For a light load of 12 to 15 pounds or less it is easy to make a external frame and bag under 1 pound.

    I think I could do a long AT Hike with that under 1 pound frame/pack. I would plan a resupply cycle of every 3 or 4 days. With my SUL/Hyper-Light Gear I am sure it would work. This would be for a typical start time of April and end on or before mid-Sept. This would put me in mild to warm to hot weather much of the hike. Cooler weather at the start or at the end would be no problem as I would just add a light extra layer or remove one from my gear. If I added some Thermo Plastic pillows to the frame and hip belt for a cooler pack the weight might go up an extra pound.

    If you wanted to extend your range it would be mostly just be more food weight. You might even be able to push 6 to 8 days with that pack. With a little more weight I would add a better hip belt than what I was using. My hip belt, which was almost nothing, failed at 22 pounds. That is when I started playing with the “wing” to help support a light hip belt. My next wing was going to be made out of Titanium. It was going to be a little wider and longer.

    I might work on a new version of a light “wing” frame while I wait for the Composite stuff and books. I would only use Titanium for the wings and keep the frame simple, maybe. I have some new foam stuff to try for the padding on shoulder straps and hip belts. It would be a good test to see how it is going to work.

    #1356694
    BPL Subscriber
    Member

    @bobone

    I’m not sure when I might be able to dig this out, but I think I must have some letters from Jack Stephenson somewhere. I remember him telling me his thinking about his waistband and wings, how, iirc, it wasn’t intended to wrap and squeeze like the typical waistband, but was trying to tie into the shelves on the sides of the hips with the wings and that it didn’t work for everyone but if I had any exposed hip bone it should. He may have said it better than I have.

    Indeed that’s what it felt like, which is like your thermoplastic setup, and like what I was trying to get at with a fiberglass hip shell close to my body.

    When Stephenson proved the bracing to the hips idea, I became confident that my old idea with the fiberglass would work out best and be lighter if it was well-fitted to one’s body and the pads were well-placed…and it could distribute the weight onto the hips more ideally than the Stephenson too. And after the advent of carbon fiber, reading Carroll Smith’s seat-making procedure, and your doing the thermoplastic work, it seems like an even better idea.

    Something like the wand idea could be added in later if more bracing for side-to-side floppiness of the top of the pack bag is needed, if the wands are resilient enough not to restrict the hip motion too much. They might also help in keeping the packbag away from the back, but I was also thinking a few horizontal floating ribs that follow the shape of your back might the light way to hold the pack bag back exactly where it’s wanted.

    #1356763
    Dale Wambaugh
    BPL Member

    @dwambaugh

    Locale: Pacific Northwest

    Hey, Bill– how about a kind of thermo-plastic vest? I guess the idea is to put the frame sheet outside the pack.

    I could see this light plastic shell that wraps over the shoulders with some padding and blend into a couple shoulder straps. The back would continue down the spine and wrap aound the hips with a belt and some pads under. The pack could strap/snap/Velcro/glue onto the frame sheet. If you got is all right, you might be able to get away with just a sternum strap. I could see it looking a little bit like a football player’s shoulder pads.

    I’m thinking of plastic a little thicker than a milk jug and LOTS of holes for ventilation and weight reduction. The pads could help with ventilation and stiffening too.

    Even with conventional shoulder straps, this could be cut out with a pair of scissors or snips.

    Add a cuben fiber bag and shake. Bake at 70F in a remote place for as long as you can :)

    #1356772
    Bill Fornshell
    BPL Member

    @bfornshell

    Locale: Southern Texas

    Dale,
    This idea has several parts that are worth pushing. The Thermo-plastic comes in several “hole” patterns but may cost more than some other material. I have some other thinner plastic material that might work if it was doubled that is real cheap, as in recycled free.

    I have two sheets of the Thermo-plastic that are 2′ by 3′ if the idea got far enought along to really make one. The Thermo-plastic I have is mold-able at 150 degrees F. It was 95 degrees in My TEXAS Village this afternoon.

    The vest idea takes us back to a “fishing/military vest” type set-up of sorts. I could see something like stunt men used to hid a parachute in when it looks like they get pushed or something out of an airplane. Like a “James Bond’ movie piece of equipment. I may still have one of my old ones packed away in my “Q” room.

    I got my Composite Practic Kit this evening. I was getting ready to open it and see what all it has in it. It comes with a book that is said to be very good.

    I will post a comment later after I have a look in the box.

    I also got a few things from an early Dillion Patagonia Memorial Day Special sales notice I got last week. I got a Micro Puff Pullover and will put a full 2-way seperating zipper on it. When I cut it for the zipper I want to have a close look at how they sew in the insulation. It fits nice but I had to turn my AC lower as I was getting to warm. Now that my house is about 50 degrees the Micro Puff really feels good. Life is so good.

    #1358251
    Dale Wambaugh
    BPL Member

    @dwambaugh

    Locale: Pacific Northwest

    I came across an old Jansport kid’s external frame pack at a thrift store this weekend and I’ve started dissecting it. I’ll get some pictures together and post them soon.

    These packs were mini versions of the adult packs with small diameter aluminum tubing and an adjustable top bar for torso length. Of couse the pack bag is heavier PU coated nylon. The hip belt is like an old seatbelt– two straps bolted to the frame and a big steel buckle.

    I stripped the bag and the hip belt off the rig and with just shoulder straps and the two padded back bands it weighs 18.5oz. I think that is promising. With some Ti tubing, mesh back band(s) and a Spartan hip belt, the weight could at least stay the same (we’re adding the hip belt). A big silnylon pack liner could be strapped to the frame I have and would still be under 24oz.

    #1459111
    Paul Tree
    Member

    @paul_tree

    Locale: Wowwww

    how about this for your satellite Bill, UCO Compact Firebowl from REI:fowl

Viewing 9 posts - 76 through 84 (of 84 total)
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