Few machine stitching problems vex quilters as much as thread tension troubles. Skipped stitches, loops forming on the top or bottom of the stitch line, puckering always seem to arise at an inconvenient time. (Not that there's a good time for a tension crisis.)
Sometimes problems with tension can be anticipated, such as when you're stitching on slippery, thin fabric or thick or uneven textiles. But sometimes, tension issues just seem to "happen." When they do, relax and try these trouble-shooting tips from machine quilting expert Susan Brubaker Knapp:
Tension Troubleshooting Tips
Machine stitching tension problems are tricky to resolve because there are so many variables. Here are some things to try:
1. Completely remove the top thread and the bobbin thread, and re-thread the machine. Always thread your machine with the presser foot up. It sounds too simple a solution to work, but sometimes that's all it takes.
2. Make sure the innards of your machine are clean and oiled (if recommended by your machine manufacturer).
3. Change the bobbin thread. Try a different kind of thread (polyester or monofilament), or a finer (higher number) thread.
4. Try a different type or weight of top thread. Discard old, brittle thread.
5. Use the correct spool pin. Cross-wound thread should be placed on a horizontal spool pin. Parallel-wound (also called "stacked") thread should be placed on a vertical spool pin.
6. Make sure your bobbin is wound correctly. It should be wound at medium speed, and, when done, should be firm and snug on the bobbin.
7. Seeing bobbin thread on the top? Bobbin tension could be too loose, or top thread tension could be too tight. Tighten bobbin tension first. If you have a Bernina, try threading it through the little hole in the bobbin case "finger" first. Turn the bobbin case screw clockwise to tighten. Move it a tiny amount at a time. (Caution: Always note the position of the bobbin case screw before you change it. You can make a drawing, take a digital photo, or mark it with a fine-tip permanent marker on the case itself. Some people prefer to purchase a second bobbin case for tension adjustments.)
NOTE: I've had people tell me I should never, ever change my bobbin tension by messing with the screw. To them, I reply, "If you were never meant to change the bobbin tension, why did the manufacturer put that screw there?"
8. If problems persist on the top, loosen the top thread tension (move it to a lower number, one number at a time until the tension is right).
9. Seeing top thread on the underside? The top thread tension could be too loose, or bobbin tension could be too tight. First, tighten the top thread tension (move it to a higher number, one number at a time).
10. If problems persist on the underside, loosen bobbin tension. Turn the bobbin case screw counter-clockwise to loosen. (See cautions in tip 7.)
Susan offers many more tips tricks, and advice on her video tutorials, Master Machine Stitching and Master Machine Quilting.
P.S. Do you have tension trouble-shooting advice? Share it below.