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First myog backpack test (thanks to David Chenault)


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Home Forums Gear Forums Make Your Own Gear First myog backpack test (thanks to David Chenault)

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #1330981
    Ivo Vanmontfort
    BPL Member

    @ivo

    I would like to thank David for his insights.
    I used his experience to make my own prototype
    of a backpack.
    backpack
    Cheap material is used for this first test.
    myog
    For the frame, I used laminated oak.
    laminated oak
    Strong and not as heavy as aluminum.
    His last myog backpack article was the basis for my design.
    Supplemented with the article "Contoured side panels for improved load carry in frameless packs"
    contoured
    Some thoughts in dutch on my blog

    #2216395
    Nathan Meyerson
    BPL Member

    @nathanmeyerson

    Locale: Southwest

    Looks great! And for your first, it looks very well made.

    Cheers!

    p.S. What kind of sewing machine do you use?

    #2216471
    Ivo Vanmontfort
    BPL Member

    @ivo

    I work with a singer samba 4 machine

    #2216514
    Nathan Meyerson
    BPL Member

    @nathanmeyerson

    Locale: Southwest

    No way! That's the first sewing machine I ever called my own. I pulled mine out of a dumpster my freshman year of College.

    Treated me well for years. Struggled sewing through more than a couple layers of heavy fabric and working with Foam was a pain, but there are ways around those issues.

    Exciting to see that same machine Again. Mine was given to a friend a couple years subsequent when I picked up a Pfaff 130.

    Nowadays I can't imagine using anything non-industrial short of a sail rite.

    But I still remember the good old days…

    #2216533
    David Thomas
    BPL Member

    @davidinkenai

    Locale: North Woods. Far North.

    Great job! I've always like the laminated wood stays when people go that route.

    Making the thin layers of oak is quick enough on a table saw (although you make more sawdust than veneers). But here are a few other ideas:

    Other, lighter density woods will give you the same stiffness in only a little more thickness and, overall, save weight. No one uses oak in an airplane, right? For highest strength to weight, they use spruce (specifically Sitka Spruce).

    A layer of fiberglass on each side of the wooden stay really leverages the strengths of each materials – wood and FG.

    An easy source of wood veneers without sawing your own is 1/8" plywood. I keep a sheet or two of it around at all times for various projects, but another, potentially free source of veneers are any interior doors or closet doors – they are all hollow-core with thin veneers glued to some cardboard blocking on the inside. I dumpster-dive for those, made easier because our trash transfer station lets you put useable stuff to the side for others to salvage. I've made foam-core ladders (every light weight) and BIG fishing nets (we're allowed to catch salmon in a 5-foot-diameter net) by laminating strips of that very thin plywood. Usually, it is 3-ply and 2mm, 3mm or 1/8" in thickness.

    #2216648
    Ed T
    BPL Member

    @peyotezen

    Really nice looking work!
    Ditto on the selection of wood.
    Best strength/weight ratio is found in softwoods.
    Western Red Cedar could be a good choice for resisting rot.
    It's generally not as strong as spruce though.
    With the softwoods the selection of the piece itself and how it is sawed is critical.
    You want quartersawn with tight grain for highest strength.

    #2216678
    David Chenault
    BPL Member

    @davec

    Locale: Queen City, MT

    Briljant!

    #2216717
    Ivo Vanmontfort
    BPL Member

    @ivo

    I

    Thanks for the comments

    I like how kifaru makes his stays (wood+carbon)

    kifaru

    I was thinking about using plywood
    but I had my doubts about it.
    In plywood, the veneer is crosswise bonded and not in the same direction.
    What is the impact on the strength?
    I soak the wood a short time in water to give it shape.
    Sometimes the glue they use for plywood is not very water-resistant
    But maybe I should giving it a try.

    #2216750
    Ken Thompson
    BPL Member

    @here

    Locale: Right there

    Fjallraven uses laminated birch stays. Lighter and better carbon footprint than aluminum they say.

    #2216795
    [ Drew ]
    BPL Member

    @43ten

    Locale: Central Valley CA

    Whoa, those Kifaru stays look fantastic. Available for purchase?

    #2216817
    Ivo Vanmontfort
    BPL Member

    @ivo

    I do not know.
    but when myog, then it's adjusted to my back.
    You can not curve a Kifaru stay.

    #2216818
    David Thomas
    BPL Member

    @davidinkenai

    Locale: North Woods. Far North.

    >"In plywood, the veneer is crosswise bonded and not in the same direction.
    What is the impact on the strength?"

    The thin plywood is usually 3-ply, so the outer layers are going lengthwise, while the inner layer is going crosswise. That does help reduce the chance of it splitting (if you haven't bonded it to FG or CF). It would reduce the longitudinal strength a bit compared to all grain going lengthwise, but the inner layer's effect as a spacer – getting your outer layers further apart – is a huge help in strength and stiffness.

    >"I soak the wood a short time in water to give it shape.
    Sometimes the glue they use for plywood is not very water-resistant"

    The really nice stuff is knot-free, BS-1088 Marine Okoume as is sold for constructing boats (I've made four).

    But I've had no problems with "door skins" during the assembly process nor in extended outdoor use (some bits have been out in the sun and rain for 5 years now), if I coat it thoroughly with a decent quality finish. Stepping up to a "spar varnish" and those pieces and boats look fine now, 15-20 years later.

    But my best answer is: experiment. Slap together a stay from solid wood and another one from glued-up plywood strips. Quick & dirty. Weigh them and then test them to destruction on a bathroom scale. PM me with dimensions if you want some plywood strips mailed to you.

    #3417433
    Ivo Vanmontfort
    BPL Member

    @ivo

    Recent new attempt
    Thanks David, 3x 3mm Plywood strips were the way to go.
    They are not much lighter than oak (240gr/for two 650x10x25 mm stay’s)
    took the easy way: no carbon fiber inside
    Some pictures and a link to some (dutch) thoughts

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