Bobbin Tension Calibration

Download the 7x30mm test file here.

This tutorial will help you properly calibrate your bobbin tension. After loading and completing this test file, you will notice the good side (top side) will look identical, this does not mean they are all the same.

Flipping it over will reveal the difference, it is very important to have the bobbin tension set correctly, as it may cause thread breaks or other issues. It is recommend that you calibrate all your new bobbins, the settings may change if you change threads that are significant different in weight.

1. Bobbin too tight/top thread too loose (Tension screw all the way in)

2. Bobbin too tight/top thread too loose (Half turn counter clockwise)

3. Perfect top thread and bobbin tension (One turn counter clockwise)

4. Bobbin too loose/top thread too tight (Almost not tension at all)

Please read our tutorial on top thread tension adjustment here.

Please read our tutorial on bobbin threading here.

Ideally you want the test file outcome like #3. 1/3 thread, 1/3 bobbin thread and 1/3 thread.

Please adjust bobbin tension accordingly to get proper tension, the tension is adjusted with the small flat head screw on the bobbin case. To loosen tension turn screw anti-clockwise, to add tension turn screw clockwise.

You will see two screw, please adjust the larger one. ONLY do small adjustments, half a turn would make a significant difference. Go half/quarter turn at a time until ideal tension.