Creating the Perfect Stitch

The tension controls on a serger are actually stitch selectors. Each thread has its own tension control. Changing one or more tension settings affects the character of the stitch, because it changes how the threads loop together. With tension adjustments, the serger can stitch a wick range of threads, fabrics, seams, hems, and decorative treatments.

A good way to become comfortable with serger tension adjustments is to thread each looper and needle with a contrasting thread color. Copy the color code used for the machine’s threading diagram. Make several stitch samples, tightening and loosening the tensions in sequence. You will see the effect of each tension adjustment and learn how to use the tension controls to create a balanced stitch. Most of the stitch samples shown below and opposite were made on a 3-thread serger; stitch samples made on other models look similar and are adjusted in the same way.

Correctly Balanced Tensions

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(left) 3-thread stitch is formed by two loopers and one needle. Upper (orange) and lower (yellow) looper threads form neat, smooth chain at raw edge. Needle thread (green) forms flat stitches without puckers. (center) 4/3-thread stitch is formed by two loopers and two needles. Upper (orange) and lower (yellow) looper threads chain neatly at raw edge. Both needle threads (blue, green) form flat stitches that interlock with looper threads. (right) 4/2-thread stitch makes double row of stitches with two loopers and two needles. Left needle thread (blue) interlocks with lower looper thread (yellow) to make neat, pucker-free chainstitch. Upper looper thread (orange) and right needle thread (green) interlock over raw edge.

Common Tension Adjustments

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(left) Upper looper too tight. Upper looper thread (orange) pulls lower looper thread (yellow) to top side of fabric. Loosen upper looper tension so threads interlock at raw edge. (right) Lower looper too loose. Lower looper thread (yellow) rides loosely on top of fabric. Tighten lower looper tension until stitches lie flat and smooth on fabric.

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(left) Upper looper too loose. Upper looper thread (orange) interlocks with lower looper thread (yellow) underneath fabric. Tighten upper looper tension so threads interlock at raw edge. (right) Lower looper too tight. Lower looper thread (yellow) pulls upper looper thread (orange), causing stitches to interlock under fabric. Loosen lower looper tension so threads interlock at raw edge.

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(left) Upper and lower loopers too tight. Fabric bunches and puckers within stitches. Loosen upper and lower tensions until fabric relaxes. (right) Upper and lower loopers too loose. Lower (yellow) and upper (orange) looper threads interlock beyond raw edge and form loose loops. Tighten both looper tensions so stitches hug raw edge.

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(left) Needle too tight. Fabric puckers or draws up lengthwise when needle thread (green) is too tight (a). Loosen needle tension until fabric relaxes. Test knits for thread breakage, loosening needle thread if necessary. On 4/3-thread machine (b), adjust each needle thread (blue, green) individually. (right) Needle too loose. Needle thread (green) forms loose loops underneath fabric (a). Tighten needle tension for flat, smooth stitches. On 4/3-thread serger (b), adjust each needle thread (blue, green) individually.