Why is my sewing machine bobbin thread bunching up?

Why is my bobbin 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 keep fabric from bunching when sewing?


  1. Reduce the tension applied to the thread while it is being wound onto the lock stitch bobbin.
  2. Set the needle thread tension to be as light as possible while achieving a balanced stitch at the same time. …
  3. Use a high-quality sewing thread with a low-friction lubricant applied to it.

How do you fix the bottom tension on a sewing machine?

If the tension isn’t perfect, fix it by adjusting the bobbin spring; tighter if the bobbin thread shows on the upper layer, and looser if the needle thread shows on the underlayer. Make another test seam, and examine the stitches, repeating until the stitch is balanced.

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