Episode 902

Serger Success

Serger Success by Sarai Mitnick & Alyson Clair

Get the most out of your serger with tips and techniques from the pros.

Troubleshooting with the Serger

Sergers are specialty sewing machines designed to sew knits, and to finish edges on both knit and woven fabrics. When using a serger to create knit garments, there are some common issues that crop up. We'll walk you through those issues and how to avoid them - before you sew your whole garment.

Start by taking a look at your machine manual and learning to identify each part of the serger, particularly the needles and the upper and lower looper. We recommend threading your serger with 4 different colors of thread and sewing some test stitches. Notice the role each thread plays in the stitch.

Before you begin sewing, test your stitching on a sample of your fabric. Here's what to look for.

Testing needle tension

testing tension

If you already have your desired project fabric selected, use it for tensioning exercises. If you don't have your fabric yet, start with a stable cotton woven to give yourself a baseline for the machine.

Testing on actual fabric is something I cannot stress the importance of enough. Not only will it tell you if the tensioning on the machine is correct, but that tensioning can differ from fabric to fabric.


To test, stitch at least 4 inches. First, make sure that the threading is creating a proper stitch and thread chain. If not, open up your machine and make sure everything is threaded correctly.

Each thread can create its own issue if the tension is off. Below are some examples for quick identification of issues and how to correct them. We'll begin with 2 tests to help you test your needle tension. We'll then look at the symptoms of improper upper or lower looper tension.

Needle tension test 1: Popping stitches


Needle threads can look like fine to the naked eye, while they actually have performance issues later when they're worn. There are two quick tests to make sure your project will work. First, stretch your stitch, like you would if you were testing out your fabric. If your tension is correct you should get the same resistance from all threads of the stitch.


If you have any popping, it is almost always your needle thread. You should be able to feel and hear this. If one or both of your needle threads has popped, this means that your needle tension is too tight. Loosen one number at a time, and keep stitching until you are able to stretch your stitching without breaking. Nothing is worse than thread popping along the waistline of a garment!

Needle tension test 2: Seam stretch and grin through

The second thing to test is your tension for holding the garment together. Always check this after the first test.


For this test, use 2 layers of fabric to simulate a seam. Sew a few inches, then take a look at the stitching. It may look fine when coming off the machine, but you still always want to check this.

grin t hrough

On the right sides, grab each side of the fabric and pull to what you think is a reasonable amount of stretch. Think about how much you anticipate stretching the garment in wearing. If you see the stitches obviously, this is called grin through and your needle thread tension is too loose. If you encounter this issue, try tightening your thread tension dials in small amounts until you a can get this to stop happening. If you do a large jump to a higher tension, you may develop the first problem of tight needle threads and stitches popping.

Checking looper tension

Upper looper

upper too tight

upper too tight back

When the upper looper is too tight, you'll notice the upper looper threads (red) look too narrow, and are pulling on the lower looper (blue) threads. Try lowering the upper looper tension dial and test again.

upper too loose

upper too loose back

If the upper looper is too loose, the upper looper threads (red) wrap around to the underside of the fabric. The stitches appear loose. Try raising the upper looper tension.

lower too tight

lower too tight back

If the lower looper is too tight, the lower looper threads (blue) pull the upper looper threads (red) to the underside. The stitches appear tight, and may pull on the edge of the fabric. Try lowering your lower looper tension.

lower loose

lower loose back

If the lower looper is too loose, the lower looper threads (blue) wrap around to the top side of the fabric. The stitches appear loose. Try raising the lower looper tension.

Trouble shooting

Sometimes even all the correct threading and tensioning in the world cannot help if you have something mechanically out of whack with your machine. If you're frustrated by trying to tension or sew, these identifiers may help.

Compressed air

compressed air

Machine crankiness can often be solved by removing any fiber build up in the machine. It is amazing how much fiber from both thread and fabric ends up in the feeddogs, loopers and cutting knife.  Compressed air is used in industry settings, though some machine manufacturers recommend lint brushes or small vacuums.

Issue 1: Not enough tension

grin through

If you tighten the tension disc and still having grin through problems, the cause could be your tension discs themselves. Sometimes tension discs can lose tension over time. To test if this is an issue, make sure your thread is inserted properly through the tension dials and turn the dial to the highest setting. If you have no difference in resistance, your tension discs are having issues.

cleaning with denim

First, clear away any fibers that may have built up in this area. Then take a piece of dense fabric, such as denim or heavy twill. Trim the edge so you have a clean straight line without and threads hanging. Insert the fabric like you would the thread into the tension disks and move up and down. This will dislodge any other fibers or build up that are left. After cleaning, try rethreading the offending tension disc. If you are still having the same problem without any improvement, it is time to take your machine in for servicing.

Issue 2: Timing is off with loopers

poor stitch formation

This problem can be pesky to identify. If the timing of one looper is off, it can mess up the stitch and thread chain. The result is that you may be able to sew, but when you take your seam out of the machine, it has garbled rows of stitching and the loopy part of the stitch is not forming correctly. If you feel confident that you have your machine threaded correctly but you cannot get a chain to form, take it in. If the timing is off, a tune up from a mechanic will take care of that.

Issue 3: Metal on metal

Just like your car breaks, the sound of metal grinding on metal is the worst thing to hear in your machine. I have joked that not only am I "The Chainsaw", but also "Home Serger Godzilla". I borrowed a friends machine one time and was able to break a looper in half in under 60 seconds. That is a much more costly repair than a tune up! If you hear clicking, grinding or metal noises, that is the cue to stop sewing and get your machine to the hospital as soon as possible.

Issue 4: Old needles

replace needle

If you are sure you have your machine threaded correctly, the tensions are all correct, the machine is stitching, and you are still having trouble forming a stitch, there is one more possible culprit: your needles. Be sure to change your needles frequently. A worn out needle can cause all sorts of problems with your fabric and your stitching.

How to get your serger serviced

If you do take your machine for any type of service, make sure to take an example of the stitching problem on fabric with you to show the technician. It is amazing how many ways you can explain and describe something, but one sample is worth 1,000 words.

Also, when you pick your machine up, make sure that you take the time to test it in person at the shop. Nothing is worse than getting a machine home, only to find it is still having problems. 

Products used in this episode:

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