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  1. #1
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    straight stich Vs. Zig Zag

    A question for all those out there who have been making Hammocks for a while. When sewing the channels why use straight stitch instead of a Zig Zag? I was always taught that Zig Zag worked better in aeas where the forces pulled perpendicular to the stitch?

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    Senior Member Ramblinrev's Avatar
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    Quote Originally Posted by docmusolf View Post
    A question for all those out there who have been making Hammocks for a while. When sewing the channels why use straight stitch instead of a Zig Zag? I was always taught that Zig Zag worked better in aeas where the forces pulled perpendicular to the stitch?
    My concern with zig-zag in high stress areas is the zig zag is a poor man's stretch stitch. It is a bias based stitch which would allow tension to be absorbed into the stitching. For high stress areas like pocket bar tacks that might be fine. But otherwise, it subjects the thread to greater load forces and could potentially cause the stitch to fail.

    That's my story... and I'm sticking to it.
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  3. #3
    Senior Member Oper8or's Avatar
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    Quote Originally Posted by Ramblinrev View Post
    My concern with zig-zag in high stress areas is the zig zag is a poor man's stretch stitch. It is a bias based stitch which would allow tension to be absorbed into the stitching. For high stress areas like pocket bar tacks that might be fine. But otherwise, it subjects the thread to greater load forces and could potentially cause the stitch to fail.

    That's my story... and I'm sticking to it.
    That is dang good to know. I was considering this stitch when I make my dual layer bed. Not to highjack this thread but if we were to make a dual layer hammock should straight stitching be used? I noticed a few vendors use a zig zag stitch on the running edges, not the head and foot ends of the hammock.

    How can we allow the stretch without zig zag stitching? Is there a better/stronger method than straight stitching? I hope I'm not coming off as being the tail end of mule here. I'm really curious and want to make my hammock correctly. I realize its one of those YMMV situations and there is a lot that comes into play, all things considered.
    Last edited by Oper8or; 08-09-2012 at 09:17. Reason: remove vendor names
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    Senior Member Ramblinrev's Avatar
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    The longer the stitch the greater it's flexibility. In other words, short stitches are more likely to snap under sudden loads. But the longer the stitch, the less stable it is. In other words, long stitches will slide around more than short ones. There is no mathematical formula for the best stitch length. It is one of those intangibles that you pick up through practice and experience. But by and large it is probably not a critical distinction. Use the stitch length that "seems" right and you will probably be okay.
    I may be slow... But I sure am gimpy.

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    This seems to be a more complex question than I originally thought it would be. I googled this and have come up with a number of different results from various gear manufactures and their thoughts on the question of straight vs zig zag. It seems to come down to the combination of thread and material and shock loading. Below is a synopsis of some of what I found.:

    1. On long seams, such as a tent or tarp: if the thread has lower stretch than the fabric, i.e. polyester thread on nylon, a zigzag stitch will keep the thread from snapping when the stronger nylon fabric stretches. And it will prevent the thread from sawing against the fabric until one or the other fails. The zigsag does not have to be deep, just enough to give some slack when the long seams stretch.
    2. Sailmakers use a zigzag - which is also called the "sailmakers' stitch" partly because sails are subject to a lot of wind shock causing the seams of bias cut fabric to stretch, and partly because it is easy to rip out zigzag stitches when a seam needs adjustment during manufacture as it often does.
    3. If the thread has the same stretch as the fabric or more streth than the fabric, a straight stitch is stronger.
    4. Consider whether the seams are square or on the bias. Even polyester sailcloth strethes when pulled on the bias. For bias seams, the stretch of nylon thread makes the seam stronger.
    5. Tests reported on this site have shown that parallel lines of straight stitches are stronger for reinforcements in ultralight fabric than are zigzags or bar stitches.
    6. Gear manufacturers (including sail makers) usually just learn from experience like everyone else and apply rules of thumb. In general outdoor gear, the tendency has been to use long stitches with strong, stretchy thread. It works and long stitches are easier to remove when (not 'if') a mistake is made. General purpose polyester thread is strong enough for almost all DIY projects except perhaps sails. Lightweight nylon upholstery thread is good for DIY sailmaking and when sewing heavier fabrics such as 10 oz or heavier Cordura.
    7. Things get tricky with climbing gear because of shock loading versus static loading. Improper over-stitching can weaken webbing, for example. You just have to know. And test. Carefully.


    so it also appears that the number of stiches per inch are critical as well. I will have to run a test seam and count the stiches.

    I have only ever worked with heavy fabrics so will need to find some thinner thread and smaller needles for work on a hammock.

    Ohhhhhhh so much to learn.

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    It's a thought provoking discussion, but keep in mind that all of us hammock making hacks have been making hundreds+++ of hammocks with a wide variety of miss-matched fabrics, threads and straight stitch lengths and while I'm sure someone has had a stitch break, I don't recall it ever being reported. Don't get too caught up in the details of a low failure rate non-critical side hem.

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    Senior Member Oper8or's Avatar
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    Quote Originally Posted by gmcttr View Post
    It's a thought provoking discussion, but keep in mind that all of us hammock making hacks have been making hundreds+++ of hammocks with a wide variety of miss-matched fabrics, threads and straight stitch lengths and while I'm sure someone has had a stitch break, I don't recall it ever being reported. Don't get too caught up in the details of a low failure rate non-critical side hem.
    No no. I completely understand what you are saying. I'm not taking it to seriously. For instance: I've learned that a straight stitch that is to tight (short stitch length) makes for a terrible edge on a hammock! It can act like a saw if you run your arm up and down the edge in the middle of the night. A longer stitch works great. I was just considering a zig zag on the outside edges if I put two pieces of material on top of one another. Now I will always use a straight stitch on the head and foot end, its just stronger and can take the stress better with my suspension.

    I love this place. It can be so thought prevoking.
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    Senior Member Pag's Avatar
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    If you're really wanting to get into it you could look up a local cut and sew shop. Take a peek at their stitch setup books. Most shops keep track of what they have done for future reference and if you ask nicely they might show what they've learned in the millions of pieces they've made. At the shop I work at we have it broken down into applications and then seam type, fabric weight, fiber, weave/knit type, yarn count, stitch type, stitch length, thread type, thread size, needle size, and several others that are application specific.

    One of my teachers once told me that you could make a 1000 sq ft banner hold up in 100 MPH winds using embroidery floss with the right stitching, and you might get it right on the 50th try if you're lucky.

    A true stretch stitch isn't a zig zag either, just had to throw that in here. Zig zag is really useful for shocks on either thin or really thick fabrics. On thin fabrics it reduces the risks of running tear failures (fatigue induced failures) and on thick fabrics it helps avoid only catching the weft yarns. For real stretchy situations a chain type stitch is king (there's plenty chain stitches to choose from).
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    Senior Member Ramblinrev's Avatar
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    Quote Originally Posted by Pag View Post
    A true stretch stitch isn't a zig zag either, just had to throw that in here.
    That's why I called it a "poor man's stretch stitch". Home machines started featuring it when the knits became widely available during the Stretch and Sew era. Zig zag was all the home machine had at that point. But you are correct... stretch has moved far beyond that now.
    I may be slow... But I sure am gimpy.

    "Bless you child, when you set out to thread a needle don't hold the thread still and fetch the needle up to it; hold the needle still and poke the thread at it; that's the way a woman most always does, but a man always does t'other way."
    Mrs. Loftus to Huck Finn

    We Don't Sew... We Make Gear! video series

    Important thread injector guidelines especially for Newbies

    Bobbin Tension - A Personal Viewpoint

  10. #10
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    Thanks for all the insight. This has all cleared the murky water a bit.

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