How to thread a sewing machine correctly

Threading a sewing machine correctly comes down to three things. The upper thread must follow the machine's marked path with the presser foot raised, so it seats properly in the tension discs. The bobbin must be wound evenly and placed in its case in the right direction. And the bobbin thread must be brought up through the needle plate before you start sewing. Many threading problems, including loops, nests and broken thread, come from skipping one of these steps or doing them out of order.

Most machines print a threading diagram on the body, with numbered guides, and the manual shows the same path. Follow the numbers in order and treat the diagram as the reference. A missed guide is one of the most common reasons a machine seems to sew but produces loose or uneven stitches.

Winding the bobbin

Place the spool on the spool pin, using the spool cap or felt pad that came with the machine so the thread feeds off smoothly. Lead the thread through the guide on the bobbin winder, wrap it a few times around the bobbin by hand, then push the bobbin winder into position. Press the foot pedal or start control and let the bobbin fill evenly. Stop before it is overfilled, usually when it reaches just below the rim, because an overfilled bobbin may not sit correctly in the case.

Wind with a little tension on the thread. Too little tension produces a soft, bulging bobbin that can wobble in the case, while too much can deform the bobbin. If the wound thread looks uneven, unwind it and start again. A firm, neat bobbin gives consistent stitches, and a poor one is a frequent cause of uneven tension on the underside of the seam.

Threading the upper path

Raise the needle to its highest position by turning the handwheel toward you. Raise the presser foot as well. Lifting the foot opens the tension discs so the thread can slide between them, and lowering it later clamps the thread in place. Then follow the numbered guides in order: from the spool pin, through the first guide, down into the tension discs, up through the take-up lever, down through the needle bar guide, and finally to the needle.

Thread the needle from front to back, or use the needle threader if your machine has one. Leave a tail of about 10 cm (4 inches) of thread hanging free. If the thread pops out of a guide as you pull it through, stop and start the path again. Do not force the thread past resistance, because resistance usually means it is in the wrong place or caught on something.

Seating the bobbin and bringing up the thread

Hold the bobbin so the thread unwinds in the direction shown in the manual, which is often counterclockwise for drop-in bobbins. Place it in the bobbin case, then draw the thread into the slot in the case and under the tension spring, leaving a tail of about 15 cm (6 inches). Drop the case into the bobbin area, or latch it into place, according to your machine's design.

Hold the upper thread tail lightly with one hand. Turn the handwheel toward you one full rotation, which lowers the needle and raises it again while the hook picks up a loop of bobbin thread. Pull the upper thread gently, and the bobbin loop should rise through the needle plate. Draw both tails behind the presser foot, lower the foot, and begin sewing. Lowering the foot matters because the tension discs only grip the thread when it is down.

Fixing loops, nests and broken threads

Loops on the underside of the fabric usually mean the upper thread did not pass through the tension discs. Raise the presser foot and rethread from the spool. A nest of tangled thread beneath the plate often means the upper thread slipped out of the take-up lever, or the bobbin thread was not seated under the tension spring. Clear the nest, rethread both threads, and try a short test seam.

Broken thread often points to a missed guide, a burr on the needle or throat plate, a damaged spool, or thread that is too old or too thin for the job. Check the path first, then the needle, then the bobbin. If the bobbin thread runs freely when you pull it, with no resistance at all, the bobbin was probably placed backward or is not under the spring.

After any rethreading, sew a short line of stitches on scrap before you start the project. Check both sides for even stitches, and confirm that the stitches lock in the middle of the fabric. Doing this takes less time than stopping partway through a seam to find a threading fault.

Threading gets quick with practice, and the sequence stays largely the same from one machine to the next. Raise the needle and the foot, follow the guides, wind an even bobbin, seat it correctly and bring the bobbin thread up before you sew. If a problem returns after a clean rethread, check the needle next, since a damaged needle can cause problems that look like threading errors.