Will you adjust tension on bobbin thread?
As shown in the illustration, hold the bobbin case against a smooth vertical surface. If the thread with the weight attached is slowly pulled out, the thread tension is correct. Use the included standard screwdriver to turn the tension-adjusting screw and adjust the thread tension.
Why is my thread bunching 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 tighten thread 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.
What tension should I use for cotton?
Cotton requires a moderate tension setting, usually between three and four.