Serger Tension

balanced lower looper (red) and upper looper (blue) thread

This weekend I took another sewing class at Stone Mountain and Daughter from Terry McClintock. This one was focused on the Serger. And let me recommend to you: if you are struggling with tension on your serger, I recommend setting aside a few hours some afternoon to just play with the tension on your serger. Of course, it helped to take a class under Terry's guidance, but having a whole afternoon to work on tension without having to worry about completing a garment was a huge bonus. Lest I forget what I learned, here are some serger tension adjusting techniques.

First, some serger basics before you even mess with thread tension:

1. Make sure that the telescoping thread loops are all the way extended.

2. Purchase quality thread like Tru-Lock.

2. Thread the machine in the correct order: usually upper looper, lower looper, right needle, left needle.

3. Make sure the thread is securely in the machine, running through the tension spots.

4. Before sewing, make sure to lower the presser foot.

OK, now let's look at thread tension issues. The thread tension should remain the same no matter what fabric you use, but will need to be adjusted for different types of stitches (3-thread, 4-thread, rolled hem, flatlock, etc.).

Looper Thread Problems:

lower looper (red) goes up and over
the raw edge towards the top.

-->Lower looper thread goes over the raw edge towards the top.

Solution: The upper looper is too tight; lower the upper looper tension.

-->Upper looper thread goes over the raw edge towards the bottom.

Solution: The lower looper is too tight; lower the lower looper tension.

Needle Thread Problems:

large "railroad tracks" are visible on
the right side of the garment

-->On the right side of the seam, railroad track stitches show through.

Solution: Tighten the left needle thread (4-thread) or the single needle thread (3-thread).

--> Fabric puckers when seam is opened.

Solution: Loosen the needle thread.


Correct Tension:
It is important to take your serger in for a tune up about every year so that serger tensions can run smoothly around 4-4-4-4 (left needle - right needle - upper looper - lower looper). My serger is was waay out of whack (think 7-4-0-3) before my tune-up. Post-tune-up, here's what works for me:

4-thread: 4-4-4-4, stitch length 3
3-thread: X-4-4-4, stitch length 3
3-thread rolled hem (non-stretch): X-4-3-10, stitch length 2
3-thread rolled hem (stretch): 7-4-3.5-3.5 ??
3-thread flatlock: 0-0-0-7 ??
4-thread flatlock: 0-0-0-7 ??

To find out how to do these different stitches, check out the Serger Stitch Dictionary.