Sewing Machine Tension
I rand across this great article on sewing machine tension in Threads Magazine and wanted to share it. When you tension is out of control it’s a nightmare and sometimes it’s very hard to get it readjusted.
by Claire Shaeffer
excerpted from Threads #78, pp. 39-41
Many sewers avoid the tension dials on their machines like the plague, certain they’ll only make matters worse if they make adjustments. In fact, there’s nothing very mysterious about setting and adjusting thread tensions on your sewing machine, whatever its make and model. What’s potentially more confusing is that many apparently tension-related problems are caused by factors other than misadjusted tension dials. Let’s look closely at how to identify and correct “tension” problems, both with and without touching the tension settings.
Meet your tension tools
In order to form a row of stitches that looks the same on both sides of the fabric, the same amount of thread needs to flow from the spool and the bobbin simultaneously. This is accomplished by running the threads through various tension devices, including the thread guides, tension discs, and tension regulator on the machine head for the upper thread(s), and the bobbin-case spring for the bobbin thread (see “Tension devices and proper threading”-right). Some sewing machines also include a small hole in the bobbin-case finger, through which to feed the bobbin thread to increase the tension for improved stitch definition when topstitching, satin-stitching, and embroidering, without touching your tension settings.
The tension discs and tension regulator together are called the tension assembly. The tension discs squeeze the thread as it passes between them, while the tension regulator controls the amount of pressure on the discs. On older machines there are only two tension discs, controlled by a screw or knob. On newer models there are three discs controlled by a dial or key pad on the front of the machine, which can regulate two threads at once.
In either case, the tension regulator is elementary: When adjusted to a higher number (turned clockwise), the discs move closer together, increasing the amount of pressure. Turned to a lower number (counterclockwise), the discs move apart, decreasing the pressure. Using a thicker thread without resetting the dial will increase the pressure and cause the upper thread flow to decrease, unless you’ve got a newer machine that makes automatic upper-tension adjustments. Since the bobbin tension is not self-adjusting, the lower tension may need to be adjusted manually to match. (photos from Threads Magazine)