Serger Sewing Machines

Serger sewing machines like the Juki MO-644D serger are great machines to have if you sew a lot of clothing or like to use knit fabrics. They make stitching strong, professional-looking seams a breeze. Yet when sergers stop stitching correctly due to tension problems, they can become aggravating to deal with. Fortunately, you can easily correct various thread tension issues by using the methods below.

Serger Thread Tension Basics

Sergers can create a large number of stitches used to make consistent and attractive garment seams. Many of these stitches require you to adjust the thread tension on the machine. Therefore, it is not uncommon to find that the tension needs adjusting at some point.

Generally speaking, serger machine manuals recommend loosening the tension when sewing with heavier fabrics and tightening the tension when stitching on lighter fabrics. Your manual should include instructions on how to adjust the machine for each type of stitch it can produce.

Always refer to your users manual when initially setting the tension. If you make adjustments, do so one thread or knob at a time. Make sure to test the stitching after each change. Whenever you adjust the tension on one of these machines that uses multiple threads, it should be done gradually.

Correcting Common Thread Tension Problems

When serger sewing machines have stitching problems, it usually means there is a tension issue. Depending on the symptoms you see, the correction will differ as well:

  • Fabric Puckers Under Stitched Edge - When you see fabric puckering together at the stitch line at the front and back of the seam, it means the thread tension is too tight. Slowly loosen the tension until the fabric no longer puckers.
  • Thread Loops on Underside of Stitching - If you see loops or "v’s" made from the top thread on the underside of your seam and the seam easily pulls apart, the thread tension on your Juki MO-644D serger is too loose. Slowly tighten the tension until you only see a tiny bit of the top thread and the seam feels tight and secure.
  • Lower Thread Pulled Through to The Top - When you start seeing the lower looper thread pulled all the way through the fabric so it is visible on top of the seam, the thread tension is out of balance. You can either tighten the tension of the lower looper or loosen the tension of the upper looper to correct this. Adjust slowly until tension balance is restored.
  • Upper Thread Pulled Through to Bottom - When the upper thread is pulled all the way through the fabric and you see it on the underside of the seam, the tension of each of the threads is again out of balance. In this case, you should either tighten the tension of the upper looper or loosen the tension of the lower looper. Adjust slowly until the balance is fixed and the machine is stitching normally again.

Before deciding to throw in the towel if you experience stitching problems with sergers like the Juki MO-644D serger, calm down and breathe before you tackle the issue. As problematic as thread tension issues can be, they are easily corrected on most sergers. Simply inspect the stitches to determine where the problem lies, then make the necessary adjustment to get things working correctly again. In no time, you'll be back to appreciating the great qualities that serger sewing machines bring to your projects!

Juki MO-644D Garnet Series Serger

Serger Sewing Machines