Why will my sewing machine not pick up the bobbin thread?

This is a setup fault, not a mechanical one, in almost every case. The machine picks the bobbin thread up by hooking the top thread right around the bobbin, so anything that stops the loop forming or stops the bobbin thread being free to be caught produces exactly the same symptom.

Step by step

1. Turn the handwheel towards you, never away.One full revolution, slowly, with the presser foot up and the top thread held loosely in your left hand. Turning it backwards runs the mechanism out of sequence and will not produce a loop.
2. Check the bobbin turns the right way.There is a small diagram beside a drop-in bobbin, or an arrow on the case. On most drop-in machines the thread should come off the bobbin anticlockwise, forming a shape like a lower-case letter p or q depending on the model. A bobbin in the wrong way round is the commonest single cause.
3. Check the bobbin thread is under the tension spring.Pull the thread through the slot in the case or plate and along until it clicks under the flat metal finger. If it is simply lying loose in the well, the hook has nothing tensioned to catch and the thread will not come up.
4. Check the needle is fully home and the right way round.Push it right up into the clamp until it stops, with the flat of the shank towards the back on most domestic machines. A needle sitting even a millimetre low puts the loop out of the hook's reach.
5. Check the top thread goes through the eye front to back.Threaded back to front, the loop forms on the wrong side of the needle and the hook sweeps past it. Some machines are threaded left to right instead — check the diagram on the machine.
6. Check the bobbin is the correct class for the machine.Bobbins that look identical are often a fraction of a millimetre different in height or diameter. A slightly wrong one sits at the wrong depth in the case, wobbles, and is picked up unreliably or not at all. Buy bobbins by the model number, not by eye.
7. Check for thread jammed in the race.Remove the bobbin and the needle plate if it comes off without tools, and look for a wrapped tangle of old thread around the hook. Lift it out with tweezers. A single trapped strand is enough to stop the hook cleanly.
8. Rethread the top completely, foot up.A top thread not seated in the tension discs sometimes will not form a loop tight enough to be caught. Rethreading costs a minute and eliminates it.
9. Then test again and draw both threads back.Once the bobbin loop comes up, pull it through with a pin or your fingers, and lay both tails back behind the presser foot before you start sewing. Starting with the tails forward drags them down into the race and makes a tangle.

Tips

• Some modern machines have a needle-threader and a thread cutter and are designed to be started without drawing the bobbin thread up at all. If yours is one of them, the manual will say so — but drawing it up manually never hurts.
• If it picks up only sometimes, suspect the bobbin class or a burr on the hook rather than your technique.
• A bobbin wound on a different machine, or wound too fast, can be uneven enough to sit badly. Rewind it slowly and evenly.

Common mistakes

• Turning the handwheel away from you — The loop only forms as the needle rises after bottom dead centre, and the hook timing follows that. Backwards, the sequence is wrong and the thread tangles round the hook instead.
• Forcing the machine with the foot pedal to make it catch — If the loop is not forming, running the machine only wraps thread round the race and can strike the needle against the hook, which damages both.

If it doesn't work

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