A nest of thread under the fabric — usually at the very start of a seam — has two common causes, and neither is the bobbin.
The top thread is not in the tension discs. With no top tension, the hook pulls through far more thread than the stitch needs and it piles up underneath. Re-thread with the presser foot up, so the discs are open and the thread drops into the channel.
The thread tails were not held. At the start of a seam, if both thread tails are loose, the first stitch can pull the top thread down into the bobbin area instead of forming a loop. Hold both tails gently behind the foot for the first three or four stitches.
Two more contributors.
Starting at the very edge of the fabric, where the feed dogs have nothing to grip. Start a few millimetres in, or begin on a small scrap and run onto the piece.
Take-up lever not at its highest point when you began, so there was no slack for the first stitch.
If a nest forms mid-seam rather than at the start, that is different — check for lint in the bobbin race and a bobbin that is the correct class and wound evenly.
Questions people actually ask
Do I need to hold the threads every time?
It is a good habit and it costs nothing. On some machines it is essential; on others only at the start of fine fabric.
My machine jams and the wheel will not turn.
Thread jammed in the race. Remove the needle, plate and bobbin case, clear it by hand, and never force the handwheel.
Last reviewed 2026-08-11