What causes thread to loop?
Looped stitches are usually caused by improper tension. If the loop is on the upper side, it may be corrected by loosening the top tension or by tightening the lower tension. … Looping of stitches is sometimes caused by placing the bobbin in the bobbin case the wrong way.
If your thread is pulled tight on the underside and not forming an even stitch then (counter-intuitively) it’s usually the top thread tension that’s wrong. Sometimes very lightweight fabrics such as sheers can get dragged down into the machine so it’s a good idea to use a straight stitch plate.
What setting should my sewing machine be on?
Most sewing is done in the 2.0 to 2.5 range. If you are foundation paper piecing, you may want to decrease your stitch length so that the paper tears away easier. Top stitching and quilting are usually done in the 3.0 to 3.5 range.