Backpack questions

Discussion in 'DIY & MYOG' started by gamemaster84, Jun 21, 2020.

  1. gamemaster84

    gamemaster84 Trail Blazer

    Hi All,

    I'm thinking on doing another backpack. The design will be roughly a atompacks atom+
    Propabaly this one is going for sale or I might make 2 ;)

    I might try the dyneema gridstop from Adxpert. Does anyone has experience with this fabric? Do you have to bind the edges to keep it from fraying? I usually just stitch the seems twice. Otherwise I'll just go with xpac21.

    And for shoulder straps, does anyone have a favorite pattern? The last ones I made work but they are a bit to wide and brush against the arms when walking.
    Any help is greatly appreciated!
  2. Enzo

    Enzo Thru Hiker

    I like dxg and x21rc xpac, I like to sew the seam, roll and stitch the seam down when I make packs but others prefer to bind the edges. Pros and cons to both. If using x21 you can tape the seams with cuben tape the way I do it.
    Straps are personal, but these work for me
    15927391542338203347435620011480.jpg
    Cranston and gamemaster84 like this.
  3. Dave V

    Dave V Moderator Staff Member

    Grid is one of my favourite fabrics to work with, especially if/when the grid is straight without curvature. I currently cut either with a roller of tailoring scissors that require sharpening after about 4 meters of cutting. I always heat treat the edges with a lighter, I do this with most woven fabrics tbh. I am hoping to turn the two jobs one soon by investing in a hot knife setup.

    For the straps, are you using a straight seam or angled one for attaching them? You could lay a bit of paper or card under your last pack and trace the attachment angle. Then use something like wonder clips or pins to test out the angle on the back panel before attaching them. Once you're happy, make another tracing and you then have the angles worked out for any future packs you make.
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  4. Whiteburn

    Whiteburn Thru Hiker

    I usually cut fabric with a hot knife (old kitchen knife & gas stove) it saves a lot of faffing melting the edges with a lighter or binding edges; it also provides a use for all the part used gas canisters I collect around the bothies in the 'gorms.
  5. gamemaster84

    gamemaster84 Trail Blazer

    The shoulders straps I used on my zpack clone are attached with webbing to the pack. Advantage I found it can angle out freely. So it's a bit more adaptive to the user I think. But it takes al lot of time to create a pack like that. I want to try out a more cinvential design now.

    My straps were 52cm long and 10cm wide with 1cm seam allowance.

    Good idea about he hit knife. I was looking into buying one. But this suggestion is more cost effective :).

    @Enzo do I understand correctly that you fold the seam over and create a felled seam? How do you do that with the side pockets and attachments that are worked into the seam? Don't run a seam over that?

    @Dave V I came across this angle design. Does that work do you think as a base to test with? [​IMG]

    Thanks for the tips everyone!!!! :)
    Cranston and Dave V like this.
  6. Dave V

    Dave V Moderator Staff Member

    Looks very similar to what I do. @theoctagon first introduced me to this probably three years ago. I started off with a 3.5cm offset from the top centre. I then took the angle of slope and cut the foam inside the strap to this same angle. That allowed me to measure a known distance from the foam, I used 3cm, mark that our, chalk or something and that gave me the stitch line.

    I found, after one or two packs, I got the correct angle and have in a way used it ever since but with a few tweaks when making packs for kids and more recently a lady who asked female strap design to be used.

    Creating card templates as you go really helps, it may seem wasteful but I have reused the card for smaller templates when I have made changes.
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  7. gamemaster84

    gamemaster84 Trail Blazer

    Thanks Dave!
  8. Dave V

    Dave V Moderator Staff Member

    No worries, I am on nights but when I wake up fully I will grab one of my original templates and photograph it on my cutting board so you can get an idea of scale. I'll try and find a strap template too.
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  9. gamemaster84

    gamemaster84 Trail Blazer

    That would be great!
  10. Teepee

    Teepee Thru Hiker

    I've tried all the strap build methods and prefer to triple sew inside out, then stuff with foam afterwards and sew through the straps and webbing to stabilise the foam.

    As for shape, J straps are nice and easy. There are plans online from the Gossamer Gear G4 build. They can be quite comfy, I've got a great feeling J strapped MYOG pack. If your unsure, I recommend sewing buckles into the pack so you can change the straps if they are uncomfortable. Cutting straps off and resewing a new set onto the old ones is frustrating.
    A good shortcut is to copy the straps on a pack you find comfy. Just trace round them.

    Personally, I made 10 different S shaped straps until I hit 'strap Nirvana' with the last set. I carry more weight than most (regularly over 20kg, sometimes over 30kg) and so I find the strap shape to be critical for all day comfort. Like Dave says, make card templates.

    You can sew the straps straight or at an angle, as long as you make sure they allow for an 11 degree slope of the shoulders it's good.
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  11. gamemaster84

    gamemaster84 Trail Blazer

    Thanks Teepee!
    The slope is it determined also by the torso length?
    That was 1 of the things why I made a zpacks arc so I can dial in a good torso height.
    That will be my next problem. Calculating a good torso height :(
    Teepee likes this.
  12. Dave V

    Dave V Moderator Staff Member

    These are two strap versions I've used previously for packs with hipbelts 40ltr and above.

    Similar but slight variations, the white card design worked better, the angled top is the foam cut I used as mentioned above.

    IMG_20200621_180338.jpg

    Here is a back panel template I use for a 24ltr internal pack. Obviously scale as needed but the top angles match the straps above.

    IMG_20200621_180529.jpg

    When doing the folded seam, attaching the straps and any other components, you may want to cut the bottom panel a little wider the first few times.

    This is the but of pack making I dislike the most. Getting the fold to look neat, with everything in the right place and aligned correctly. I have messed it up so many times when trying to rush. I go slow and gripple check everything now hah.
    Cranston likes this.
  13. Teepee

    Teepee Thru Hiker

    Measure your torso. :)

    No, the slope is the angle of the shoulders from horizontal.

    If I'm making a new style of pack, I personally make the hip belt height adjustable so I can dial out an inch of variance.
    Cranston likes this.
  14. gamemaster84

    gamemaster84 Trail Blazer

    I was thinking the same thing. I think I'll add velcro so I can adjust the height of the belt a bit.

    My torso is 48cm, on what height should I attach the shoulder straps?
    Sorry for all the questions ;)
  15. gamemaster84

    gamemaster84 Trail Blazer

    @Dave V Thanks for the photos! That a great help!!
  16. Dave V

    Dave V Moderator Staff Member

    I think of the back panel as two separate parts. The Strap panel and the extension. The Strap panel is the back length of the individual and then I work the extension height after. To simplify construction. I made the last two sets of straps and the backs together, a small batch. The panels are longer and shorter than needed so I can adjust and chop off the excess depending on back length. I will continue to do this as it will speed things up for me and the material cut off can he used for the webbing triangles and/or the top webbing closure on my packs.

    I would cut the back panel at 52cm for you (pack with a belt), that would give 2.5cm seam allowance at the top for the folded seam with the straps. I allow a little more here to allow for two rows of stitch after the seam fold and the bartacks. I also give 2cm seam allowance at the bottom so I can double roll that seam as it will have a lot of weight/stress on it, leaving your 48cm back length from the start of the straps to the bottom of the pack.
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  17. gamemaster84

    gamemaster84 Trail Blazer

    Great advise thanks!
  18. gamemaster84

    gamemaster84 Trail Blazer

    I created a illustrator pattern of you're design @Dave V
    Are these correct in sizes?
    [​IMG]
    [​IMG]
    Dave V likes this.
  19. gamemaster84

    gamemaster84 Trail Blazer

    On a side note, how do you add images directly in a post? I only can insert with a link so i use snipboard.io
  20. Dave V

    Dave V Moderator Staff Member

    Those look correct, obviously the lengths for both increase as required. What application are you using for that, looks very handy.

    Ref the picture, forum supporters get a few perks for the subscription. Being able to directly upload is one of them.
  21. gamemaster84

    gamemaster84 Trail Blazer

    Ah that sounds logical :)

    I use adobe illustator to create patterns. Very precise and easy to add seam allowence.


    For the straps, what seam allowence do you use? And is it included in the image?
    Dave V likes this.
  22. Dave V

    Dave V Moderator Staff Member

    Thanks, I've never though of using illustrator for that. That will help me justify the CC subscription a bit more moving forward :)

    The pencil lines on the template I uploaded are my seam allowance, that is an older template and I now use 2.5cm for the fold seam with the straps and 2cm at the bottom.
  23. gamemaster84

    gamemaster84 Trail Blazer

    Great thanks!!
    I use illustrator for all my patterns. This is a quick sample of a backpack pattern made to fit on 1m of dyneema
    [​IMG]
    I just make a drawboard of the size of the fabric and started drawing. Then with shift path you can specify a seam allowance
    Dave V likes this.
  24. gamemaster84

    gamemaster84 Trail Blazer

    And on the straps? I don't see any lines there.
  25. Dave V

    Dave V Moderator Staff Member

    Thats really cool :)

    I use some of the other CC apps quite a bit and it never crossed my mind to use it :)

    Thanks

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