I have a serger that does Cover Hem…but I find it actually quicker & easier to do my knit hems with a twin stretch needle on my machine…Even, parallel rows of stitching on top and zigzag o bottom give a good-looking, stretchy yet stable hem.
Londa’s Steps for Success
1. Insure side seams are stitched so that the lower edge is plenty snug around the hip – knowing that the operation of stitching the hem is going to stretch the fabric to some degree… Be careful on sleeve hems – making sure you can still get your hand through!
2. Establish hem allowance and gently press up into place. At fold, clip into seams so that you can press the seam allowance of the hem in the opposite direction that you've pressed the seam allowance on the garment - thus 'balancing' the bulk'. (This assumes vertical side garment seams are serged together, not pressed open.)
3. Using approx 1 1/4" wide cross grain strips of knit fusible interfacing, or Knit Fusible Tape* and NOT stretching it as you work, fuse to the inside of the hem allowance - (for Tape - place approximately at the depth where you will be stitching.) This will add stability and also prevents the ‘bump often obtained with twin needle stitching (desired for narrow pin tucks, NOT for knit hems). If you still get a ‘bump’, consider lowering the upper tension a bit.
4. Thread machine for twin needle stitching. I find using either 2 spools of thread (with identical spool caps) OR 2 identical bobbins assures even, identical feeding of the thread. Having the threads unwind in opposition from the thread source is helpful. If possible, have both spools riding either vertical or horizontal. Experiment regarding the tension disc, as your machine may do better with the threads separated at the tension disc (keeping left side thread to left needle, etc.) OR, it might do better with both threads on the same side of the tension disc (try both threads on the left or right sides of the disc). Experts differ here – so experiment on your machine. Different threads might react differently.
5. Stitch equidistant from the folded edge – right side of garment up at the machine. Make use of the Quilt Guide, a Post Note, Tape, etc. on the machine bed for a physical guide along which to guide the hem fold. Top threads may be pulled to the wrong side, threaded on a hand needle and buried in the hem allowance – this is preferable to tying a knot. (For a creative hem, do a subtle ‘wave’ as you stitch.)
6. Holding hem and garment so that you can SEE garment, trim any excess hem allowance that is wider than the stitching up close TO the stitching. Gently STEAM before judging your results!