Why is tension adjustment important? A balanced stitch doesn't just look better, but it actually makes for a stronger seam. Once you get your tension right you won't have to reinforce a serged seam with the sewing machine.
So grab a scrap of mid-weight fabric (like quilting cotton), click the link below and I'll meet you by your machine!
This tutorial covers tension adjustments for the 3 or 4 thread overlock stitch.
Just as a reference, here is a picture with the serger's tension dials labeled. The higher the number, the harder the tension disks will squeeze the thread and and the tighter the thread will be.
I've threaded the machine with 4 different colors of thread:
Left Needle: Green
Right Needle: Red
Upper Looper: Black
Lower Looper: Sky Blue
Just like with our sewing machines, it's best to adjust tension using a similar weight fabric to our project fabric. This is a scrap of quilting cotton that I sent through the machine right side (pretty side) up.
If you are starting from scratch, start by setting all the tension dials at 4.
First, lets look at what we want. A balanced stitch is one where the looper threads (the black and blue threads in the picture) meet right at the edge of fabric and the needle threads do not pucker or gape.
For 4 thread stitching you will need to adjust both needle thread tensions; in 3 thread stitching there is only one needle thread tension to adjust.
Tight Needle Tension:
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.
Loose Needle Tension:
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.
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.
If the upper looper thread is being pulled to the bottom of the fabric...
In these pictures, the black thread is being pulled to the bottom (wrong side of the fabric). The upper looper tension could be too loose or the lower looper tension could be too tight. Here you have to make a judgment call about which to adjust first.
Try looking at the thread-- in this picture the threads look pulled tight, so I would loosen the lower looper tension.
In this picture the threads look loose and gappy, so I'd tighten the upper looper tension.
If the lower looper thread is being pulled to the top of the fabric...
In this picture, the blue thread has been pulled to the top (right side) of the fabric. This means the upper looper tension could be too tight or the lower looper tension could be too loose.
Again, if the threads look loose and gappy, tighten the lower looper tension. If the threads look pulled taut loosen the upper looper tension.
Tricks and Tips:
1) If you aren't sure what's wrong, start by adjusting the needle tensions, and then work on the looper tensions.
2) Try using a slightly different color thread in one of your loopers so you can easily tell which looper thread is misbehaving. For example, 90% of the time I use cream colored thread in my needles and upper looper, and white in my lower looper. I can tell the difference when I'm trying to adjust the tension, but it's not noticeable on my finished project.
3) You can use the same scrap of fabric over and over when you are adjusting--simply position the fabric so the serger trims off the old serging.
Once you've figured out the settings for a balanced stitch you should just need to make minor adjustments to accommodate different types/thicknesses of fabric.
If you have any questions or tips of your own, leave a comment below or use the contact form on the menu above. I'd love to hear from you!
Hope to see you back here next week for the next serger 'Relationship Rescue' post!