Loading ...
Sorry, an error occurred while loading the content.

Re: [Hammock Camping] Zigzag stitch - good or not?

Expand Messages
  • Rick
    ... I tried the zigzag stitch after I saw that it was used along the length of some elastic in a piece of clothing. It allows the elastic to stretch. I am
    Message 1 of 6 , May 9, 2006
    • 0 Attachment
      jwj32542 wrote:
      > In an email a while back, Youngblood questioned the usefulness of
      > the zigzag stitch in an insulated hammock. He said that as it
      > stretches in one direction, it necessarily contracts in the
      > orthogonal direction. So if you stretch it vertically, it will
      > contract horizontally and therefore stress the material.
      >
      > Admitting that this is how the zigzag stitch works, I've been trying
      > to apply it to insulated hammocks. I have two ideas on how it
      > should work...here's what I came up with:
      >
      > - Start with an insulated hammock just like Risk described in the
      > recent post - basically, a large rectangle with a smaller rectangle
      > sewn to its center...whip it into a hammock.
      > - That means you have four seams _inside the hammock body_ that
      > might cause structural failure. I'll call the ones running across
      > the width of the hammock near the user's head and
      > foot "perpendicular seams" and the ones running down the length of
      > the hammock "parallel seams".
      > - When you lay in the hammock, most of the stress is along the
      > centerline, or the ridgeline, as evidenced by the hammock stretching
      > in length more than it stretches in width (actually, that's an
      > assumption I'm making b/c it seems to makes sense). That's why I
      > chose parallel seams - the seams are parallel to the force vector.
      >
      > Why zigzag seams work better than straight seams:
      > - If most of the force is along the centerline, the seam will
      > stretch along the hammock's length and compress along the width.
      > - However, since the hammock's ends are whipped, the material at the
      > perpendicular seam is already bunched up. That means that the seam
      > compressing perpendicularly to the force WON'T stress the material
      > in that direction.
      > - That means that zigzag seams do indeed reduce the stress on an
      > insulated hammock better than a straight seam.
      >
      > Why zigzag seams are no better than straight seams:
      > - Just use a longer stitch length
      > - Then, for the perpendicular seam at least, it won't matter if the
      > hammock stretches - the seam can't expand in the parallel direction,
      > and the material isn't stressed in the perpendicular direction.
      > - Using a longer stitch length means fewer holes per inch...to about
      > the same number of holes as a zigzag stitch...which reduces the
      > impact of the seam whether it's straight or zigzag.
      >
      > - One problem I see with this is that the hammock's material will be
      > stretched in the middle of the perpendicular seam more than at the
      > ends of that seam - which may pull the thread tighter, which will
      > stress the fabric.
      >
      > - It also doesn't address the stretch in the parallel seams, but
      > since these are near the hammock's sides they don't get a lot of
      > stress, either.
      >
      > So which one is right? I'm leaning more towards the "zigzags are
      > useful" side because of the problems I noted with the straight
      > seams. Anyone see anything wrong with this analysis? Any other
      > issues I didn't include? Dave? Bueller? Anyone? :)
      >
      > Jeff
      >
      I tried the zigzag stitch after I saw that it was used along the length
      of some elastic in a piece of clothing. It allows the elastic to stretch.

      I am generally only interested in the stress imposed by the material
      stretching along a line of stitching and the stitches not stretching as
      much, pulling into the occupied hammock and away from the plane of the
      material.

      I am going into my second year of testing this sort of stitch. It
      should still be considered experimental.

      Rick
    Your message has been successfully submitted and would be delivered to recipients shortly.