Why is my bobbin thread Birdnesting?

Why is my bobbin bird nesting?

Bird nests occur when thread bunches up underneath the needle plate, causing broken threads, skipped stitches, or uneven tension. This is typically caused by the top thread not being threaded correctly or a sewing machine tension issue.

What tension should I use for thin fabric?

Use size 70/10 for really thin cotton like voile, size 80/12 for light to medium weight cotton, and 90/14 for thick cotton like denim.

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