Why is my thread looping underneath?
A: Looping on the underside, or back of the fabric, means the top tension is too loose compared to the bobbin tension, so the bobbin thread is pulling too much top thread underneath. By tightening the top tension, the loops will stop, but the added tension may cause breakage, especially with sensitive threads.
How do you fix sewing tension?
Changing Bobbin Tension
You should see a small screw on the flat/closed side of the bobbin case. Turning the screw a tiny bit counterclockwise will loosen the bobbin tension; turning it clockwise will tighten the tension.
The tension could be too tight or too loose. Set the tension to the basic thread tension setting or adjust the tension manually. The combination of the needle size, thread size and fabric is incorrect. Be sure to use the correct size needle and thread for the type of fabric that you are sewing.
How do you adjust bobbin tension?
To tighten your bobbin tension, turn the tiny screw on the bobbin case a smidgen clockwise. To loosen bobbin tension, turn the screw counterclockwise. A quarter turn or less is a good place to start.