Serger Tension Settings

I had an email asking about my serger, and in the process of trying to explain how I find tension settings I thought "this would make a great blog post".   I use a scientific-ish method, typically changing one setting at a time.  The test results are written down on scratch paper, then the final settings are noted along with the fabric type, number of layers, and other information.

Recently I serged cotton jersey, 2 layers, with a 3 thread stitch and 2mm stitch length.  I usually make note of the stitch width as well.

My notes looked like this, x representing the unused needle:

                                  L R UL LL  [left, right needles, upper looper, lower looper]
2 layer jersey, 3thr 2ℓ    x  4  5½  5     lower looper tight; upper looper wraps under
                                             x  4  5½ 3½   upper very loose
                                             x  4  6½ 3½   skips stitches
                                             x  4  4    4      upper loose
                                             x  4  5    4      Final setting


Next time I need to serge cotton jersey I'll save a great deal of time testing settings.  Some tweaking is usually required, especially when changing stitch length or width, and that is also noted.  I keep very close watch on these notes as you can imagine!  Cotton jersey may work close to 4-4-4-4 base settings but muslin and poly satin have quite different characteristics.  That's not even getting into rolled hems!