Now that you’ve met your serger and have a basic understanding of each feature’s function, it’s time to talk about the tension. This won’t seem important until you start sewing, but you will come back to your tension test all the time!
Having the correct tension will not only make your project look better, but it will make for a stronger seam.
This Tension Test tutorial covers tension adjustments for the 3 or 4 thread overlock stitch. The pictures are of my machine; I use the Brother 1034D.
Keep in mind that the higher the number, the harder the tension discs will squeeze the thread therefore the tighter the thread will be. Here is a picture with the tension dials labeled as a reminder.
For this tension test, it’s important to have different color thread. If your machine is new, it will come pre-threaded with four colors. Keep them that way while you are creating your tension test. I color coordinated my thread to the colors on the machine – to eliminate confusion.
Left Needle: Yellow
Right Needle: Red
Upper Looper: Green
Lower Looper: Blue
To start, cut out 4 long pieces of fabric, preferably around 30″ long by 6″ wide. I used white fabric to show the contrast difference in thread color.
Fold your fabric in half, hot-dog-style. Divide your fabric into ten sections of 3″. Label each with the numbers 0 – 9. Then label each of the four strips of fabric coordinating with one of your tension dials (Left needle, right needle, upper looper, and lower looper).
Now, start each of your tension dials at “home” or wherever your particular machine recommends the tension to sit. For my Brother 1034D, it’s at the number 4.
Tension Test for the Left Needle:
1. Start with your piece of fabric at your serger. Turn your tension dail to 0, leaving the remaining three tension dials at 4. Begin serging until you hit your first line.
2. Turn your tension dial to 1, and continue serging.
3. Repeat until you have gone through all the corresponding numbers.
Now, Repeat this tension test technique for the Right Needle, the Upper Looper, and the Lower Looper.
When completed you will have something that looks like this:
Take a minute to look at all of the numbers. You will notice which sections look like they have a balanced stitch. This is what you are looking for. A balanced stitch is one where the looper threads (the green and blue threads) meet right at the edge of fabric and the needle threads do not pucker or gape.
Compare these three sections for the upper looper tension test. The #3 is too loose. #4 is a balanced stitch. #5 is too tight.
Do you see how the blue thread is either being pulled too much or not enough? It’s being pulled by the green thread.
As you look over the tension test do you see any sections that pucker? If the needle tension is too tight, the fabric will start to pucker and ripple. This is great for ruffles, but not for regular serging. If you see this, loosen the needle tension until the fabric doesn’t bunch up.
Let’s take a look at this picture below for a minute. They are both of the right needle. The picture on the left is the front side, the picture on the right is the back side of the tension test strip. Do you see on the left picture how the blue thread is showing through? It is not supposed to do that. Look at the picture on the right, see how towards the top you can see the red thread poke through, but towards the bottom it’s the green thread. That is wrong. Both of these are signs your thread is too tight.
Do you see any sections in your tension test that seem to be too loose? If the needle tension is too loose, there will be loops on the back of the fabric. If you see this, tighten the needle thread tensions until the needle thread just barely shows on the wrong side of the fabric.
In the picture below, notice the blue thread. It is supposed to be sitting on top (or the edge) of the fabric. This indicates that it is too loose.
Now look at your looper threads on your tension test. The loopers are a bit tricky since they effect each other. If the looper threads aren’t meeting at the very edge of the fabric, take note of which thread is being pulled to the incorrect side.
Remember– the upper looper thread should be on top of the fabric, and the lower looper should be on the bottom of the fabric.
Other thoughts…
Now that you’ve created your tension tests, you can keep these around to refer back to them. When serging, if you notice something doesn’t look right, refer back to your tension test. You can match up to the section to see if you notice one of the four dials are too tight or too loose.
If you aren’t sure what is wrong, start with the needle tensions, then work to the looper tensions. Just take the same piece of fabric and serge little strips over and over until you feel the tension is meeting correctly on the fabric. If that troubleshooting still doesn’t work, check the side of your machine. Is the stitch length, stitch width, and differential feed set to the correct numbers? For a review on when to change those check here.
Once you’ve figured out the settings for a balanced stitch you should only need to make minor adjustments to accommodate different types/thicknesses of fabric. For the most part I keep the 1034D‘s tension setting on or right around the ‘4’s’ unless I’m sewing something very thick or stretchy. Before each project you should test a small piece of that fabric in your serger to make sure the tension is correct for that project.
If you have any questions or tips of your own, leave a comment below or feel free to email me. I’d love to hear from you!
Since the Learn to Serge Series has been so popular, I have put all of the lessons in one easy-to-read ebook.
Click here to download your copy. 
