Updated: March 31, 2020
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.
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.
Troubleshooting Zig-Zag Stitch Problems
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).
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).
Problem: When using a shorter stitch width, the fabric puckered under the zig-zag forming a little tunnel.
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 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.
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.)
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.
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!
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.
My main goals are to support, empower, and inspire you to discover the joy of sewing.
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