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  1. #1

    UQ, differential cut sewn through baffles?

    For an UQ, wouldn't sewn through baffles with enough differential between outer shell and inner shell work almost as good as with inner baffles but with much less work? I.e if we think of the channel as a box, the outer shell forms three sides of it.

    Diff cut uq.jpg

  2. #2
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    My custom quilt was made this way. This is called a Chocolate Baffle or Gravity Baffle. It does work better than something like a Costco blanket. I dont think it works as well as a full on box baffle. I have been tempted many times to put a blind stitch on mine to close it up. So yes it does work for far less effort but if you want 100% efficiency then go the extra mile and make the box Baffle.

  3. #3
    Quote Originally Posted by leiavoia View Post
    My custom quilt was made this way. This is called a Chocolate Baffle or Gravity Baffle. It does work better than something like a Costco blanket. I don’t think it works as well as a full on box baffle. I have been tempted many times to put a blind stitch on mine to close it up. So yes it does work for far less effort but if you want 100% efficiency then go the extra mile and make the box Baffle.
    I'm not surprised it has a name or that it's a thing already. It's hard to imagine exactly how it behaves without actually making one but my guess is you really need a thin outer shell that won't be too stiff for it to really get to close up against neighboring channels considering how light down is. Maybe even some overstuffing.

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    Senior Member WV's Avatar
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    It's also going to be somewhat heavier, even without overstuffing. It's worth using real baffles, which can be made from very light fabric or mesh. With a "gravity baffle" the bottom layer could require up to 3 times as much fabric.

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    Quote Originally Posted by WV View Post
    It's also going to be somewhat heavier, even without overstuffing. It's worth using real baffles, which can be made from very light fabric or mesh. With a "gravity baffle" the bottom layer could require up to 3 times as much fabric.
    While I agree with your basic premise, I think you have overstated the weight.

    My quilt is sewn with each chamber being 6 across the topside and 9 across the bottom. If you square that up it would give you the box-baffled equivalent of 1.5 height. The bottom side uses 50% more fabric than the top, not 300%. It consumes slightly more material than a box baffled quilt using mesh, but not much.

    I think its decent way to make a quilt especially for beginning seamsters. It is much easier to make.




  6. #6
    Quote Originally Posted by WV View Post
    It's also going to be somewhat heavier, even without overstuffing. It's worth using real baffles, which can be made from very light fabric or mesh. With a "gravity baffle" the bottom layer could require up to 3 times as much fabric.
    The lightest mesh I could find right now was about 30g/sqm (maybe there are lighter) and that's about the same weight as a light ripstop nylon. With gravity baffles the total theoretical weight of the baffles will double but the total weight of the baffles will still be pretty small.

    How much the bottom layer will increase depends on loft/baffle height, if the cross section of each channel is a perfect square, yes the bottom layer will be three times the length of the top layer. But that's mostly not the case.

    I'm not saying this would be better than real baffles, more an option to consider and have in one's toolchest when deciding on a design. Because I think it has its merits in the right situation and circumstances.

  7. #7
    Thinking about this some more I think the problem is that it will be hard to get the sides of each baffle to actually touch and close. With gravity the fabric will form catenary curves with no sides being really parallel.

    Still probably a good option in some situations.

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    Senior Member WV's Avatar
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    Valid points, all. It depends on the materials available and the dimensions you choose. I strive for uniform thickness, which means narrower tubes and taller baffles. I have some cuben fiber on hand that was deemed not strong enough for tarp construction, so I got it cheap. It's about 1/3 oz. per sq. yd. (11.24 gm/sqm, if I calculated correctly) That's what I use for baffles. I think the most important dimension of an under quilt is the minimum thickness. That's what determines warmth.
    Last edited by WV; 07-26-2021 at 19:19.

  9. #9
    Senior Member Cruiser51's Avatar
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    Quote Originally Posted by Kalle Mandelstam View Post
    Thinking about this some more I think the problem is that it will be hard to get the sides of each baffle to actually touch and close. With gravity the fabric will form catenary curves with no sides being really parallel.

    Still probably a good option in some situations.

    I didn't notice this thread till now ... but I will chime in anyway.

    The sewn through is a good option for warmer weather use, using a differential will extend that temp range some ... the only issue with the extension though , is that you will likely start to feel the cold stripes created at the seams.

    I suspect the "installed"cavity shape will be a product more of the amount and type of insulation used and the loaded hammock shape employed, than following a regular catenary shape .... under load it is still doubtful those baffles will close up, as you stated.

    I would think the "limit" for this design extension would be around the 50F mark, this being a general comment, fully realizing that individuals and gear can make a significant difference in perceived comfort. If you wanted to push the design a bit more, a light weight underquilt protector could probably get you down another 5 - 10 F, at the cost of a little more weight.




    Brian

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