My zig zag stitch is puckering fabric. I even went to the multiple zig zag, same problem. I decreased tension. What should I have double. Note: this was on single layer, along edge of fabric so I could laundry before cutting quilt pieces.

It sounds like maybe the bobbin tension is too tight. It is pulling the top thread down to the bottom of the fabric. If you tighten the top tension it causes the fabric to pucker. If you loosen the top tension, more of the top thread will show on the bottom. Correct tension is when the top and bobbin threads meet in the middle of the fabric.

Understanding Thread Tension on Your Sewing Machine

Tension will not fix the problem you are having. When sewing stretch fabric with a sewing machine, use a zig-zag or stretch stitch. Test on a swatch of scrap fabric and then pull on the seam. If the seam pops, you need to increase the size of the zig-zag stitch to allow for the amount of stretch in the fabric.

Be sure you are using a ball-point needle. Try setting the upper tension looser. You also may need to increase the presser foot pressure on your machine (consult your owner's manual if you don't know how to do this). Using a closed-toe presser foot (vs an open-toe embroidery foot) may help control the fabric and prevent it from puckering under the needle. Also, reducing the width of the zig-zag may be helpful.

Some sewing machines have an overlock presser foot. Effectively, there is a thin piece of metal in the center of the presser foot. The needle will straddle that piece of metal in a zig-zag so the upper thread has a little bit of slack in each stitch that will let the fabric lie flat. It is a very nice tool to have especially when zig-zag finishing raw edges too.
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C9store overlock presser foot how to video

Some sewists will increase the fabric's "body" by inserting a layer of wash-away or tear-away stabilizer. If it is only a small project, a piece of paper added to the seam (like adding machine paper) will help stabilize the fabric.

One last thing to try would be loosening the bobbin tension. However, there is a reason it is the last effort, because most sewists are uncertain about messing with the bobbin and it is also requires "minute" adjustments to effect a big change.

How can properly adjust my tension

Understanding Bobbin Tension

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Most sewing machines will cause puckering when zig-zaging, especially when sewing light-weight fabric like chiffon, etc. Try a brand new needle. You can try narrowing the zig-zag so there is not such a large gap between the left & right swing. Can also try loosening the tension a bit so the thread is not pulling so tightly. Another possibility (if your machine has the capability) is to increase the presser foot pressure so there is more pressure applied between the presser foot and the feed dogs. Or, try using a layer of wash-away stabilizer or clean (unused) newsprint paper with the fabric to help give it some stability.

How to Adjust Sewing Machine Tension on Craftsy

How to Prevent Your Sewing Machine from Puckering Fabric Howcast

https://groups.google.com/forum/#!topic/alt.sewing/AOhNY36JOa0

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this kind of sewing macines have a digital reset option
once you,ve done taste it again
make sure is well lubricated the main head gear

Yes, because a zig zag stitch is creating a wide stitch and the tension on the thread is going to pull the fabric within the seam together, you can't seam thin fabric with a wide zig zag. It will "tunnel together". If you are using this stitch to neaten a raw edge, then try using the serpentine or three step zig zag where the needle pierces the fabric 3 times in each leg of the zig zag, this will give better results.

When zig zagging over a raw edge, the tension on the thread will pull in the fabric, especially in lightweight cottons or even lighter organza. Its not the best edging method for very light weight fabrics. You can try using a smaller zig zag, loosening off the top tension a little bit. Or if your machine has it, use the triple zig zag or serpentine stitch, where the needle goes through the fabric three times to make up each zig stitch, this stitch is better for edging most fabrics and is my preferred stitch.

a wide zig-zag on a light weight fabric single layer is almost guaranteed to pucker up, just because the thread is under tension and this is often stronger than the fabric being pulled together by the stitches.

However, if a straight seam is puckering, this could be caused by a blunt needle, too big needle, or too tight tension or too long stitch length. You should be able to vary some of these variables to reduce the puckering and improve the stitch appearance. Other things to check might be the top thread being caught up somewhere in the thread path and pulling on the stitching.

If I am finishing the cut edge of aa single layer of light weight fabric I would use a three step zigzag to hold the fabric firmly and neatly.

Hope this helps a little?

Check the threading and tension on the top thread. It is the one that affects the stitch on the bottom. It may be hung up somewhere if it's not threaded correctly or the tension might be too tight. Also double check the size of your needle and make sure it is correct for the type of fabric. Most likely it is the tension. Double check the tension by sewing a wide zig zag stitch and examining the top and under side to see if they look identical and not puckered or too loose.

Most likely the fabric is too light weight to sustain the thread tension using a wide zig-zag stitch. Tunneling will occur in this case.

Loosening the tension (top & bobbin) could also be beneficial.

Sometimes the machine has a special foot (sometimes called overlock) that will help. However, using something to add more body to the fabric, like a wash-away or tear-away fabric stabilizer to the seam or even adding paper will help limit tunneling. Sometimes heavy starch applied to the seamline before stitching will be helpful.

tunneling when zigzagging Threads Magazine Gatherings Forum Sewing...

zigzag stitch troubleshoot