How to properly thread bobbin - Sewing Machines

needle thread tension is not adjusted up properly tighten the setting until you have resistance when you pull the thread to thread the needle

bunching of thread under the material is an indication of insufficient tension of the needle thread
increase the needle tension until the threads meet at the center of the materialbeing sewn

Check that it is actually the bobbin thread that is nesting. Generally, bobbin thread issues appear on the top of the fabric and upper thread issues appear on the underside of the fabric.

If it is in fact the bobbin thread, the bobbin thread tension may be off or malfunctioning.

If it is the upper thread nesting under the fabric:
1. Remove the thread
2. Install a brand new needle
3. ALWAYS RAISE the presser foot. This releases the thread tension so the thread will seat properly.
4. Rethread from the beginning and check the thread path is correct.
5. Set the upper tension at the midway point.
6. Check that the bobbin thread is loaded properly
7. Retest the machine.

If it continues to create thread nests under the fabric, tighten the upper tension.

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The symptoms sound like it could be the incorrect bobbin. Even if it is tiny bit different, it may not work properly. If it is not an authentic bobbin for your machine, but rather a clone from another source, it may not be suitable. Some machines are very finicky.

If it is in fact the correct bobbin, then there may be a problem with how the thread is wound on the bobbin or how the bobbin has been inserted and threaded in the bobbin case. Be sure the thread is wound very smoothly on the bobbin and that the thread does not extend beyond the outer edge of the bobbin or that no loose threads are poking out from the bobbin. Also verify that it is inserted (and turns the right direction) in the bobbin case and that the bobbin case is threaded properly.

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Make sure the bobbin is wound so the thread is smooth and even. (When winding a bobbin, use a slower speed to prevent problems.) The wound thread should never extend beyond the outer edge of the bobbin and there should be no thread pieces outside the bobbin. The bobbins do have a direction of travel when unwinding in the machine so be sure the bobbin is inserted correctly into the bobbin case and the bobbin case tension is threaded properly.

Make sure you have threaded the machine properly--which usually involves removing the thread and rethread from the beginning. Make sure to RAISE the presser foot before threading the upper thread. Check that the bobbin is loaded in the bobbin case and it is threaded properly.

sewing machine loose bobbin thread Google Search
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The needle thread breaks
1. The needle thread is not threaded properly
2. The needle thread tension is too tight
3.the needle is bent or blunt
4. The needle is incorrectly inserted into the needle holder
5. The needle thread and the bobbin thread are not set under the presser foot when starting sewing
6. The threads were not drawn to the rear after sewing
7. The thread is either too heavy or too fine for the needle
Bobbin thread breaks
1. The bobbin thread is not threaded properly in the bobbin holder
2. Lint has collected in the bobbin holder
3. The bobbin is damaged and doesn't turn smoothly

ENSURE you have threaded the bobbin properly and at the right tension. Also, ensure that you have routed the bobbin thread properly in the bobbin case.

Ensure the bobbin case has been installed properly.

Setting bobbin case tension:
Put wound bobbin in bobbin case. Thread it in case. Hold the thread and carefully let go of the case only holding bobbin thread. The case should NOT move. Quickly let your hand drop 2-3 inches to let the bobbin case free fall for 2-3 inches, the bobbin case should move slightly then stop. It moves because it let’s a little thread off the bobbin. It should then stop .5"- 2" of thread should release. If so, your bobbin case tension is right. If it’s right then begin to look at your top thread tension. Always Always start with a properly adjusted bobbin case, then adjust your top tension accordingly.