Troubleshooting the Zig-Zag Stitch

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The zig-zag stitch is a fun stitch. For me, it evokes memories of little girls and doll clothes. It’s a great stitch to use for topstitching, embellishment, and to strengthen seams. It was the second stitch I learned to sew and it’s included with the straight stitch in my free online sewing class, Starting to Sew.

I’d never had trouble with the zig-zag stitch until I was making the bean bags.

When I made a swatch of zig-zag stitches, I couldn’t figure out what was going on and had to do some troubleshooting.

Note: Post first published May 3, 2019. Last update: August 15, 2020.

The Zig-Zag Swatch

The width and length of zig-zag stitches vary. You can make them as wide and long as your sewing machine allows. When I want to use a zig-zag stitch, sometimes I create a swatch to try out different widths and lengths to get the look I want.

My plan was to reinforce the seam on each bean bag so it would be less likely to split open when we played with them. To do this, I was going to use the straight stitch to sew the seam then use the zig-zag stitch between the seam and the fabric’s raw edge.

The seam allowance on the bean bags was 1/2-inch. The zig-zag had to fit in that 1/2-inch space. So I wanted to create a swatch with zig-zags of different widths. Once I had several widths on the swatch, my plan was to use the sewing gauge to determine which width was the one I needed to reinforce the seam on the bean bags.

However, after I sewed different widths of zig-zag stitches on the swatch, three different problems popped up.

The correct zig-zag width was no longer my priority. I needed to figure out why there were loose stitches, puckered fabric, and deformed zig-zags on the back of the fabric.

three problems with the zig-zag stitch
The problems with the zig-zag stitches were evident on both the front and back of the fabric.

Troubleshooting Zig-Zag Stitch Problems

Loose Stitches

Problem: One line of zig-zags on the swatch had a few stitches that were loose on the front of the fabric. However, almost all the stitches were loose on the back (in addition to being deformed looking).

zig-zag stitches are loose on the back
The middle row of stitches on the swatch is very loose in addition to not looking right.

Solution: Rethread the machine. If that doesn’t work, adjust the tension.

Explanation: When the thread loops on the backside of the fabric, that’s an indication the upper thread is not threaded correctly. The thread is not receiving the tension it needs. This could be because it was not threaded correctly or the tension needs to be adjusted.

What Worked for Me: Rethreading the machine was the easiest solution so I did that first. This fixed the loose stitches on both the front and back of the fabric. The tension didn’t have to be adjusted (at least for this problem).

Puckered Fabric

Problem: When using a shorter stitch width, the fabric puckered under the zig-zag forming a little tunnel.

puckered fabric forms a tunnel
The tunnel is easily seen on the top row of zig-zag stitches. While not as noticeable in the picture, the fabric puckered on the last row, too.

Solution: Use a stabilizer for support or sew a heavier weight fabric.

Explanation: The fabric I was using for the swatch was one layer of light-weight cotton. It wasn’t heavy enough to support the density of the stitches on its own.

What Worked for Me: I was making two different size bean bags. One was going to be for the game Cornhole and the other was for juggling and a 3-D version of Tic-Tac-Toe.

For the Cornhole bean bags, I used Sunbrella fabric scraps I had left over from an outdoor cushion project. It has a very tight weave and feels like duck or canvas.

For the other bean bags, I used light-weight gingham and lined it with muslin. Each bean bag was 4 layers of fabric.

When sewing the zig-zag stitch on scrap layers from both types of bean bags, I didn’t get the puckering and tunnel effect. Evidently, the thickness of the Sunbrella and the 4 fabric layers were enough to support the density of the stitches without adding a stabilizer.

Deformed Stitches

Problem: The zig-zag looked liked Y’s on the back of the fabric. The zig-zag stitch should look the same on the top of the fabric as it does on the back. (Like in row 3 below.)

zig-zag stitches are deformed on the back
The tension on row 2 stitches was set on about 3.5. Row one was around 5. Row 3 looks the way I want with the tension on 6.5. The fabric puckered but I knew that would happen because of the fabric weight.

Solution: Adjust the tension

Explanation: When stitches form, the upper thread interlocks with the bobbin thread. Thread tension is good when the needle, or top, thread appears on the top of the fabric and the bobbin thread appears on the bottom.

What Worked for Me: When I did my initial swatch, the top and bobbin threads were the same color. I couldn’t tell exactly what was going on with the stitches and determine what was the top thread and what was the bobbin thread.

So, I used two different colors of thread. (As shown in the picture above.) One for the top thread which is on the right side of the fabric and another color for the bobbin thread.

The thread tension information in my sewing machine instruction manual said, “It [tension] can be adjusted to a lower number for less tension on the upper thread, if the bobbin thread seems to be showing on the top side of the fabric.”

My problem was the opposite of this. I was seeing the upper thread on the bottom side of the fabric. So, I adjusted to a higher number for more tension on the upper thread until hardly any of the top thread was visible on the wrong side and the zig-zags no longer looked like Y’s.

Top Thread Breaking

This happened to me when I decided to use the zig-zag stitch on straps for a face mask for my niece. I started a swatch to determine the stitch width and length I would need.

Problem: After taking a couple of stitches there was a crunching sound, the fabric gathered, and the top thread broke.

Front and back of a swatch showing messed up stitches
Left – front of swatch Right – back of swatch

Right before the swatch, I had just finished sewing with the straight stitch and didn’t have a problem. So, I rethreaded the machine, put the swatch back in, and took several straight stitches. No problem.

Making sure the needle was out of the fabric, I adjusted the stitch width to try out a zig-zag stitch. A couple of stitches in, the crunching sound happened again, the fabric gathered, and the thread broke.

Solution: Change the needle

Explanation: Prior to sewing the zig-zag stitch, I had just finished making face masks for family and friends. Each mask was a double layer of 100% cotton and flannel, and both sides of the mask had 3 pleats that I pinned prior to sewing.

I was making so many masks, I stopped taking the pins out (not the safest practice) to reduce the amount of time for each mask. The needle did hit pins occasionally but never broke.

As a result of sewing through thick layers and over the pins, the needle became bent and developed a burr on the end. (Which I didn’t know until I started troubleshooting.)

That bent needle must have pulled the thread too taut as it tried to zig-zag causing the top thread to break. I’m assuming the crunching sound was the needle hitting the bobbin case as it went up and down.

What Worked for Me: Prior to changing the needle, I tried other things one at a time:

  • rethreading the upper thread
  • using the horizontal spool pin instead of the vertical one
  • lowering the tension
  • rethreading the bobbin
  • using a different thread on the spool and in the bobbin.

None of these stopped the crunching sound or the top thread from breaking.

I pulled out the sewing machine instruction manual to make sure I was following their recommendations for stitch number, width, length, and thread tension on zig-zag stitches. (I was.)

Then I went to the back of the manual and looked at the general troubleshooting. Changing the needle was one of the suggestions. As soon as I removed the needle, I could see it was bent. I’m lucky it didn’t break and get lodged in the bobbin area.

Replacing the needle with a new one solved the problem!

Two rows of stitches - the left side is with an old needle and the right side is a new needle.
The new needle made the stitches on the right side of the swatch.

Troubleshooting Tips

If you have to make adjustments to tension for the zig-zag stitch, write down the tension dial number for a quick reference in the future.

Make one adjustment at a time. That way when you troubleshoot you’ll know exactly what causes the change.

Troubleshooting Sewing Problems

When confronted with a sewing problem that I don’t know how to solve, my preference is to talk to someone about it. Thank goodness my mother lives across the street from me! She has been sewing since she was a little girl and has a wealth of knowledge and experience.

When my zig-zag issues first happened with the bean bags, I took the swatch over to her to get her input on what happened and how I could solve the problems. She provided a lot of insight and several suggestions on how I could fix the zig-zag stitches.

One solution my mom gave was related to the thread tension. I’ve never had to adjust thread tension before so I used the sewing machine instruction manual to figure out what to do. This is a great resource for basic sewing issues.

While I was in the manual, I happened to come across the troubleshooting tips listed toward the end of the booklet. Several of the problems I was experiencing were described in the troubleshooting section. They weren’t specific to zig-zag stitches but more general in nature.

It was exciting to notice the advice my mother provided were the same recommendations given by the sewing machine company.

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16 Comments

    1. Paul,
      I’m not familiar with the elna contessa sewing machine, but these are the thoughts I had when I read your comment and how I would troubleshoot:
      Are the stitches loose on the top thread, bottom thread, or both?
      Are the stitches loose when you do the straight stitch?
      Depending on the answers to the questions, try rethreading the machine (both top spool and bottom) and change the needle. I would do one of these things at a time and see if it fixes the problem.
      Next, I would work on adjusting the tension. Some machines allow you to adjust tension on both the top thread as well as the bobbin thread. Refer to the sewing machine manual on tension adjustment. If you don’t have the manual, you can do a search online and more than likely find one.
      Depending on the fabric I use and the sewing machine, I need to make tension adjustments when I do the zig-zag stitch and then change it back for the straight stitch.
      My last suggestion would be to have your sewing machine professionally cleaned and serviced if it has been a while since it was last done.
      I hope that helps. Good luck!
      Nicki

  1. Hello,
    I just got my new Singer 4432 sewing machine a couple of days ago. I tried a couple of stitches. I used contrasting threads to see what happens with each of them. The problem is, that the top thread is always visible on the backside, especially on zigzag stitch. Is that normal or not? I tried making a tension higher, it looks a little better but the thread is still a little bit visible.
    I got a picture of it as an example: on the right is the upside and on the left is the backside. https://ibb.co/26rvTY2

    Thanks a lot.

    1. If the tension and pressure of the zigzag stitch is correct, the interlocking link of thread at the corner of each stitch would be midway between the fabric layers. That being said, when I use contrasting threads to troubleshoot my zigzag stitch problems, I always see the top thread on the backside in the stitch corner as pictured in your photo. As long as the fabric doesn’t pucker and the stitches are an even length, it’s a success in my opinion.

  2. You are the only site that had true hep for the pucker in my zig zag stiching. I am an experienced sewer of uncomplicated things; but I did not know about the dotted line zig zag icon. I perused your site and I love it. I signed up, but did not get a confirmation either in my in box or junk mail. I love all the pictures. Thanks for sharing the knowledge.

    1. Michele, I’m so happy you were able to find the help you needed for the pucker, and thank you for the compliments on my site and the pictures! For the sign-up confirmation issue, I sent an email to the address you provided with the comment that will hopefully allow you to get signed up. If you don’t get it, please email me directly at nicki@theruffledpurse.com.

  3. I just bought a refurbished Brother CS7205 to make masks, but everytime I go to sew through the pleats with a zig zag, it always misses the stitch on the right side of the zag (or zig 🙂 I’ve tried almost everything from re-threading, needle changing (stronger needle) to adjusting the tension to every setting. I’ve read the manual a few times and I can’t figure it out.
    🙁 Any ideas? I’m wondering if when it was refurbished, something was got messed up internally? I don’t know. Any advice would be GREATLY appreciated!

    1. By missing the stitch do you mean it’s skipping a stitch on the right and not catching the thread to form the z? Have you tried sewing the zig-zag on a non-pleated piece of fabric to see if you get the same missed stitch? If not, I would try that. If it happens on the flat fabric, it seems like it would be something with the machine. Other things I would try (one at a time) is a different type of thread on the top spool, a different type of thread on the bottom spool, adjusting the needle to the left or right, adjusting the stitch length and width. Hope that helps!

      1. I have this same issue, but only with an athletic material (relatively thin wicking jersey). I sewed using the balpoint/jersey needle just fine on a thicker material that was spandex, and wovens are fine too. Is this a needle issue? Rethreading, cleanning, oiling, tension, width etc all fine and checked.

        1. Hi Natty, I wonder if the issue is because the fabric is thin since you aren’t having the same problem with thicker material. If you have some scraps, try doubling the fabric to see if that makes a difference. Or if you have some tear-away stabilizer that works with knits, you could try that, too.

  4. I just got a vintage Kenmore Sears sewing Machine gifted to me from my boyfriends mother. It’s a 1303 Model. I can sew a straight stitch just fine but when I try to do a zig zag it’s not catching the bobbin thread. It’s probably something I’m doing wrong because this is the first sewing machine I’ve ever used. I dusted and oiled the machine per instruction manual details, I changed the needle, adjusted the upper thread tension, adjusted feed dog tension, rethreaded 100x times(lol), and even rewound my bobbin. What am I missing?

    1. Hi Ember,
      Congratulations on your new-to-you sewing machine!

      It sounds like a timing issue. Timing is the synchronization of the hook and needle and controls the stitching. It’s not unusual for the straight stitch to work but not the zig-zag or other stitches.

      When that happens to my machine, I take it to a sewing machine repair person to be adjusted. However, I did a quick search online and found a video that may be helpful. https://youtu.be/TukHI2Nb4MQ

      With all the things you’ve already tried, look at the following troubleshooting suggestions to see if any of them fixes the problem before looking at the timing.

      1. Make sure the needle is inserted correctly. Check the sewing machine manual to see which way the flat side of the needle should be facing.
      2. Check how your bobbin is inserted into the case. It should say in the manual if the bobbin should turn clockwise or counterclockwise when the thread is pulled.
      3. What type of fabric are you sewing? If the zig-zag stitches look correct on woven fabric but not on a knit, you may need to try a stretch needle. This type of needle has a rounded point and deep scarf to prevent skipped stitches.

      Hope that helps and good luck!
      Nicki

  5. Hi Nicki
    I have a very old but hearty Janome. I’m stitching a zigzag on some faux fur and after about 8 stitches there is a weird sound and the stitch just goes straight. When I turn the machine off it starts off well and then the same thing happens. I tried the zigzag on a piece of plain cotton and the same thing happened so it doesn’t seem to be about the fabric. Any thoughts?

    1. Hi Marion,
      First, I would try changing the needle and sew on a couple of layers of cotton to see if that results in a normal zig-zag stitch. If it does then I would try it on the faux fur and see if you continue to get the same result. If changing the needle doesn’t make a difference, try out the straight stitch and see if it is working properly. Email me at nicki@theruffledpurse.com if you need further troubleshooting ideas. Good luck, Nicki

  6. NIcki, I have an old Singer and have never used anything but straight stitches. I’ve followed all the manual instructions for zigzag settings but it’s still sewing straight–no back and forth at all. Any ideas of what I might be missing?

    Thanks.

    Carol

    1. Hi Carol,

      My first go-to troubleshooting steps are always to change the needle and rethread the top thread and bobbin. If you haven’t done these things, I suggest trying just to make sure.

      Based on your description, it could be a timing issue. Timing is the synchronization of the hook and needle. It controls the stitching. It’s not unusual for the straight stitch to work but not the zig-zag or other stitches. When this happens to me, I take it to my sewing machine repair person to be adjusted. However, there might be some resources online to diy timing.

      Another thought is the type of fabric you’re sewing. Are you trying the zig-zag on woven fabric or a knit? If it’s a knit, see if the zig-zag works on a woven. If you get the zig-zag on the woven, you may need to get a ballpoint or stretch needle to sew zig-zag on the knit. The ballpoint needles have rounded points for sewing with knits. Stretch needles have rounded points and deep scarf to prevent skipped stitches.

      Hope that helps,
      Nicki

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