Pack frame

Discussion in 'DIY & MYOG' started by Clare, Nov 4, 2019.

  1. Clare

    Clare Thru Hiker

    How do you make a frame? I know how to do an arc blast type frame. But what about internal ones. I get that you set up retaining pockets internally but I don’t understand:
    (1) how it connects to waist belt to transfer weight to hip

    (2) what you do to connect two side stays at the top. Delrin loop, yes okay, but how do you actually make/bend such a thing?

    (3). If you have fitted internal loops against inside of rear facing panel to hold the stays, how do you fit foam or hdpe between the stays and rear panel?

    pics welcome. And comments on weight transfer/comfort success.
  2. Lempo

    Lempo Thru Hiker

    Here's Flex Capacitor Y frame. Top pockets have velcro to open them up and that allows to lift out the frame.

  3. Jamess

    Jamess Ultralighter

    What pack are you trying to add the frame to?

    Attaching the frame into a hipbelt that wasn't intended to take a frame... I'm not trying to put you off, but I'm not sure how successful you will be.

    I have successfully used carbon rods to stiffen a frameless pack to improve the carry but without a decent hipbelt it wouldn't really carry much more weight.

    I found that I didn't need spacers at the top having experimented with coat hanger wire. YMMV.
  4. Teepee

    Teepee Thru Hiker

    Thiis is a question that needs a lengthy essay to answer. :)

    I'll try and be brief;

    1: you can pass the stays through the pack and into the belt for maximum transfer. However, this isn't needed in our typical weights (up to 30kg odd). My stays attach to the velcro pad inside the pack (Delrin/Alu/Carbon) , and then that pad transfers the weight to the belt. It's all stuck together with Velcro, held together by the tension of the hipbelt. All the pockets for the ends of the stays need to be made from reinfrced materials, PP webbing isnt strong enough. Nylon or Vectran webbing is what U use. Allt ypes sit in a channel that is sewn to the inside pack back.
    FWIW, I didn't like my T or Y frame packs I made as much as the double stay designs and have reverted (looks similar to Lempo's picture).

    2. They don't actually need connecting; the stays only need to stop the pack from collapsing ; thus preventing pulling the shoulders down and causing shoulder fatigue. I use a U shape/T shape or Delrin. Delrin bends on its own, it 's flexible. Alu rod can be bent by hand quite easily into a U, and then a spine shape. Delrin will follow the shape of your back without needing to be bent.

    3. I use a sit pad to cushion them, held in a pocket or shock cord cradle. You can also sew thin foam behind the channel to avoid abrasion issues. I prefer a sit pad because it's dual use and allows my back to stay dry.
    As for the weight transfer, Delrin type is as good as Alu on my packs. I've quite a few identical that only have the frame type variation and I much prefer the entrained plastic rod packs. Routinely, they all carry 30kg, far beyond what most of us carry on here and most of that weight is transfered very well to the hips
    Last edited: Nov 5, 2019
  5. Clare

    Clare Thru Hiker

    @Teepee thanks for the precis of the essay. I've been a bit busy and haven't digested this yet, in practical ways. Are you saying your belt is only attached to the pack by velcro?? I had a look for Delrin rod on eBay and the diameter seemed quite thick, the narrowest I saw was 4mm. I would imagine that to be as flexible as you say, it would have to be 2mm?

    @Jamess I'm not modifying a pack. I'm thinking of making another pack as I have left over 2.92 oz cuben from the last one I made, which was sadly not as PERFECT as I'd like. I thought I'd try something simpler than the very complicated set up for the z-packs suspension system that I used last time. I thought I'd set the hip belt right at the very bottom of the pack, there was a bit of underhang on my last pack, which in motion felt bad. There should be no underhang and the curve at the bottom of the pack should be greater, to reduce that downward pull. Then I thought I'd do a better race harness than my last one, which also had some less than ideal behaviours on trial. Trail, not trial. Or trail trial.*

    @Lempo thanks for the pic. Looks weird to me having it down the middle. Doesn't it hit your spine? I think I'm after the delrin loop solution. And as I understand @Teepee it doesn't need to actually fix into the hip belt structure in order to transfer the weight to hips, it just needs to go top to bottom to create rigidity.

    *Although my love of alliteration has been spoiled by Jacob Rees-Mog giving a very alliterated speech and thinking it very clever when it wasn't, and nor is mine. A great/not so great english language device dropped down the drain.
    Last edited: Nov 5, 2019
  6. Lempo

    Lempo Thru Hiker

    The belt is inside the belt and then the frame is inserted in it. On the outside of the pack where the bottom of the frame is, there's a thick pad. I think Flex's padding is very well thought out. As a therapist I work with movement and the Flex has pancake sized pads over sacrum and scapulas, so there's plenty of space with no contact to the body. This not only helps with ventilation, but also with movement. Single prod of the frame in the bottom allows rotation of the lower spine and Y prods on top follow the rotation of the thoracic spine. It's a great pack, and apparently the new version is almost as good, but it's just too short for me even the longest version. This means that either the pack is hanging off my back or hitching the belt up in the back.
    Clare likes this.
  7. Clare

    Clare Thru Hiker

    @Lempo that's very interesting although it seems counter intuitive. I take your point about allowing rotation of the lower spine, but .. I don't think I want my pack to rotate around my lower spine, I want it snug tight and not rotating. Have I misunderstood?
  8. Lempo

    Lempo Thru Hiker

    The pack doesn't rotate on its own, it's attached to the body and rotates with the body. When you walk, your upper body rotates to the opposite direction to the lower body. This creates tension/release effect on the fascial (connective tissue) loading and unloading energy like a rubber band. When this effect is optimal, it can produce 30-40% of the required energy to walk reducing the work of muscles.

    Basically there's a small twist of the body and the pack twists slightly with it, not massively, but enough to ease the movement. If you take a sponge and grab the top and the bottom and rotate them opposite directions, that's pretty much what happens in the middle of the body.
  9. Teepee

    Teepee Thru Hiker

    Yes, only attached by Velcro and the load control straps. Most of my packs are, including bought ones. Sewn on belts just aren't as good IME and don't allow the hips to move as much (Rising and falling, as well as twisting).
    50mm wide and as thick as the hipbelt, on both sides of the belt, inside a Velcro lined sleeve will carry me inside a pack without slipping. It's 'sandwiched' and pushed together. In fact, it doesn't even need collar to feed the hipbelt into. One of the y-stay pack just uses a wrap of 50mm over the hipbelt.

    4mm is fine, tons of flexibility with it. I wouldn't go thinner for your first pack. 2mm is like strimmer wire. :)

    Those load control packs are essential for me. Without them, the packs barrel about more; especially on more technical ground. These straps obviously negate the effect of the packs that Lempo's design pack does, but packs carry far better with them and I find are less energy sapping.

    FWIW, the single stay design above digs into my spine a little when I bend forward, I don't get that with the U or Delrin. It only saved 30g on the Alu frame over the U frame, and wasn't as supportive. Delrin not only provides this flexibilty, but is lighter, cheaper and needs no engineering.
    Last edited: Nov 9, 2019
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  10. Baldy

    Baldy Thru Hiker

    Have you thought of trying to get hold of an old Golite or Podsacs bag and take the frame out?
    Last edited: Nov 6, 2019
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  11. Lempo

    Lempo Thru Hiker

  12. Balagan

    Balagan Thru Hiker

    You can buy Gossamer Gear replacement stays although postage might make it unattractive. It fits into two grosgrain channels reinforced at top and bottom with webbing. It's only been available in medium for a while now.


    I added one to my KS pack and it is so much better.

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  13. Shewie

    Shewie Administrator Staff Member

    This seller on ebay gets random bits of GG stuff occasionally, only got a x small stay at the moment though
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  14. Clare

    Clare Thru Hiker

    Good idea. I wonder what the economy international shipping would be. Might not be horrendous. Possibly. I’m not in a hurry. Was thinking of it for that, hopefully quietishbperiod between Christmas and new year.
  15. Teepee

    Teepee Thru Hiker

    @Clare. Do you want me to send you some Alu rod the same as GG stays? It's not hard to bend, you should be able to do it by hand; I've done plenty of them. Just go slow and they shape up fine. Cut to length, file the ends to a round, sand them and they are good to go.

    You can put a flexicurve against your back and copy the shape. When I do this it comes out very close to the GG ones. FWIW, the earlier versions came with straight stays and folk often didn't even bother bending them.

    I'd send one of mine, but I take a big frame and it wont be right.
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  16. Clare

    Clare Thru Hiker

    @Teepee yes please I’d like to try that. Today I ordered some 4mm delrin rod from eBay and wrote to gossamer gear to find out what economy postage would be.

    to bend it, should I make a template to bend it around or can I just clamp it into my black n decker workmate and apply biceps? Gently of course.

    I was also looking at the GG description of their belt which, like yours, apparently connects with Velcro AND the stays lodge into the belt itself. Is the Velcro on the belt outer face and then the belt slides through a wide retaining loop, which is actually simultaneously the lumbar pad? If so, difficult to see how the stays could slide into the belt unless they are external.
  17. craige

    craige Thru Hiker

    There are holes in the gg backpanel where the frame comes out and slides into webbing channels on the belt.
  18. Balagan

    Balagan Thru Hiker

    I modified my old Mariposa to have the stays exit the back and connect to the belt (thread here) so here are a couple of pics that might make it clearer:

    Bottom of bag's back with large square piece of velcro. This is hidden by the bottom of the pad holding sleeve which is currently folded around the front the pack. In the old style bags like mine, the stays just went into the bottom of the bag hence the holes.


    Added webbing "tubes" to the belt. this is the side resting against your back but the back pad goes over it.


    This video explains how the frame fits into the belt pretty clearly:

    Last edited: Nov 14, 2019
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  19. Teepee

    Teepee Thru Hiker

    @Clare .. A workmate should be fine.

    Sequence; mark up where you want to need to form the 2 right angles. Form them first, then start on the curves. Once you have bent it, then you can mark exactly where the channels need to go. It's often a bit tight for me, as the channels are close to the straps and side seam, but I usually have 20mm odd either side.

    Ping me your addy and I'll send you some. The same length as the final back panel will be plenty, It'll give you plenty to play with. Thinking about it, I think I'll need to bend the U first though to get it in the post. :D 150mm-160mm wide is what I use. Is that cool?

    I work it into shape with my hands, it'll just bend between 2 hands and you can mirror one to the other by eye very well.

    @craige ..The first generations didn't go though, they stayed inside. GG made this mod on future builds. (Beaten to it by Balagan)
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  20. Clare

    Clare Thru Hiker

    OMG outdoor station make that seem complicated. Will review tomorrow. Thanks for the v useful video @Balagan -or it will be once I get past the biro instructions part. And @Teepee, yes, I think you will definitely need to bend it to post it. I’ll work out the ideal postage dimensions tomorrow :whistling:
  21. Balagan

    Balagan Thru Hiker

    Yes, the biro bit makes it look more complicated than it needs.
  22. ZenTrekker

    ZenTrekker Section Hiker

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  23. Clare

    Clare Thru Hiker

  24. ZenTrekker

    ZenTrekker Section Hiker

    You're welcome :)
  25. Lempo

    Lempo Thru Hiker

    Lots of frame detail in this video

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