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The quality of your stitch is heavily dependent on the tension of your thread. A sewing machine is comprised of two thread sources, both of which have their own tension setting. These tensions are often referred to as "Top" and "Bottom" or bobbin tensions.
The first step to ensuring correct tension is to review your bobbin, or "Bottom" tension. Once this is set correctly, it becomes the base line to which the "Top" tension will be set. (see below).
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To Check the Bobbin Tension
To check the bobbin tension, hold the thread in one hand while allowing the bobbin case (with threaded bobbin) to slide down with slight resistance into your other hand.
• The Bobbin Case should slide down with slight drag on the thread.
• The Bobbin Case should not hang in the air like a pendulum, fall freely, or stop mid-slide.
• Tighten or loosen the tension screw (Screw 1 in the picture below), until you have attained the optimal bobbin tension.
NOTE: The adjustments to the tension arm are slight. Over-adjusting will make it more difficult to reach the best tension.
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If you are still having bobbin problems check the following:
•Bent tabs on the No Backlash Spring
•Bent Tension Arm.
•Bent Bobbing Case Ears |
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Check your No Backlash Spring tabs. If they are bent up, then the spring must be replaced with a new one. Their are two types of No Backlash Springs: Solid and Non-Solid. Match the new one with the one in your bobbin case. |
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The bobbin No Backlash Spring fits into slots along the edge of the Bobbin Case. |
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The other slot is behind the Tension Arm on the Bobbin Case |
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To replace the spring, place tab into Slot 1, then bow the spring backwards with tweezers so that the spring is smaller, then relax the spring so the other tab moves into Slot 2. |
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If the Tension Arm (or Spring) is damaged or bent unnaturally, replace. Loosen Screw 2, which will allow the arm to be removed.
Replace with the new arm, and finger, then tighten Screw 2.
Screw 1 is used to adjust the bobbin thread tension. |
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Once you have correctly set your bobbin tension, move to the Top Thread Tension...
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