OK…it’s a NEW YEAR, and time for a sewing “catch 22.” The catch has to do with the method of getting the thread off the spool and into your sewing machine, in a condition to give you the best possible stitch. Home sewing machines have basically two methods of accomplishing this seemingly minor task.
Method one: spool horizontal, with the thread coming off the end of the spool.
Method two: spool vertical, with the thread coming off the side of the spool.
Some machines give you a choice as to which method you use; most do not. If the spool is mounted horizontally, as in method one, the thread comes off the spool and gets a twist each revolution around the end of the spool. The thread comes off evenly, in spite of the twist, and most manufacturers use this method. Because the thread does come off evenly, top tension is not affected and the stitch quality is even and uniform. However, especially with fine threads, such as embroidery thread, the twist can result in a tangle, which will result in an occasional knot in the thread, which will jam in the tension mechanism, causing bad stitches and/or broken needles. Whew! The cure, for those of you who suffer from this problem, is the use of a thread net or a thread stand. (Or both, in extreme cases)
For those of you whose machine employs a vertical spool, (method two) the problem of twist is eliminated, but, guesses what; there is a different problem associated with this arrangement! The thread will accelerate the rotation of the spool, releasing a loose loop of thread. When the loop is suddenly taken up, the spool is jerked into motion, causing a momentary sudden increase in top thread tension. This cyclical action will show up on your stitch as bobbin thread peeking out on the top in a regular pattern. If you are experiencing this particular phenomenon, the cure is the afore-mentioned thread stand. (You can always adjust tension to hide this effect, but the problem is still there; it’s just masked)
This is why industrial sewing machines, virtually all sergers, and some home machines, employ a built-in thread stand.