Threading a bobbin is a two-step process: winding thread onto the bobbin itself, then inserting the wound bobbin into the machine
The bobbin is a small spool that holds the lower thread on your sewing machine. Before you can use it, you wind thread onto it by hand or with the machine's bobbin winder, then drop it into the bobbin case beneath the needle plate. The exact steps vary slightly between machine models, but the basic sequence is the same on nearly all machines: wind the bobbin, insert it, and thread the upper thread separately.
This guide covers the standard method used on most home sewing machines. Check your machine's manual for model-specific details, especially if you own a computerized or specialty machine.
Key Takeaways
- Wind the bobbin by placing thread on the bobbin winder pin, pressing the bobbin against the winder wheel, and stepping on the foot pedal until the bobbin is full.
- Insert the wound bobbin into the bobbin case with the thread tail pointing toward you, then pull the thread into the tension slot.
- The bobbin thread and upper thread must both be threaded correctly for stitches to form properly.
- If stitches are loose on top or bottom, the bobbin thread is usually the culprit — check that it is wound evenly and inserted all the way into the case.
Winding the bobbin with your machine's winder
Most sewing machines have a bobbin winder mounted on the right side of the machine head. Place an empty bobbin onto the winder pin — it should sit flat and spin freely. Take your thread spool from the top of the machine and wrap the thread around the bobbin two or three times by hand to anchor it.
Press the bobbin firmly against the rubber wheel on the winder. On many machines, this action automatically disengages the needle, so the machine will not stitch while you wind. Step on the foot pedal to start the winder. The bobbin will spin and wind thread onto itself. Stop when the bobbin feels full and slightly firm to the touch — do not overfill it, or the thread will jam in the case.
Cut the thread and remove the bobbin. Trim the thread tail to about 3 inches. The bobbin is now ready to insert.
Inserting the bobbin into the case
Open the bobbin case door on the front of your machine, usually by unlatching a small lever or sliding a cover to the side. The bobbin case is a metal or plastic housing that sits directly under the needle plate. Drop the wound bobbin into the case with the thread tail pointing toward you.
Pull the thread tail into the tension slot — a small notch or groove on the side of the bobbin case. The thread should sit snugly in this slot. Pull gently on the tail to make sure it does not slip out. Close the bobbin case door and latch it securely.
Bringing up the bobbin thread before you sew
Before you start sewing, you must bring the bobbin thread up through the needle plate so both threads are above the fabric. Hold the upper thread (the one coming from the needle) loosely in your hand. Turn the hand wheel toward you one full rotation. This motion lowers and raises the needle, which pulls a loop of bobbin thread up through the needle plate hole.
Reach down and pull that loop up gently with a needle or tweezers. You should now see both the upper thread and the bobbin thread above the needle plate. Hold both threads behind the presser foot before you begin sewing. This prevents thread tangles and helps the first few stitches form correctly.
Checking bobbin tension and thread quality
If your stitches look loose on the bottom of the fabric, the bobbin thread is usually too loose. If stitches are loose on top, the upper thread is usually the problem — but always check the bobbin first. Make sure the bobbin is wound evenly and firmly, not lumpy or slack. A poorly wound bobbin causes tension problems that no adjustment can fix.
Also check that the bobbin is inserted all the way into the case and that the thread is seated in the tension slot. A bobbin that sits too high or a thread that skips the tension slot will cause loose stitches. If the bobbin is correct and stitches are still loose, consult your machine's manual for tension adjustment steps.
Winding a bobbin by hand if your winder is broken
If your machine's bobbin winder is not working, you can wind a bobbin by hand, though it takes longer and requires a steady hand. Place the bobbin on a pencil or dowel and hold it horizontally. Wrap thread around the bobbin in neat, overlapping layers, turning the pencil slowly as you wrap. Keep tension even so the thread does not bunch or slip.
This method works in a pinch but produces an uneven wind that may cause tension problems. If your winder is broken, have it repaired or replaced rather than relying on hand-wound bobbins for regular sewing.
Bobbin types and compatibility
Bobbins come in different sizes and styles. Class 15 bobbins are the most common on home machines and are plastic or metal. Some machines use Class A bobbins, which are slightly larger. Always use the bobbin type specified in your machine's manual — using the wrong size can cause the bobbin to jam or fall out during sewing.
If you lose your original bobbins, buy replacements from the machine manufacturer or a fabric store. Generic bobbins are usually cheaper but may not fit as precisely. Keep several wound bobbins on hand so you can switch colors without rewinding every time.
Frequently Asked Questions
How tight should the bobbin be wound?
The bobbin should feel firm but not rock-hard. If you can squeeze it and dent it easily, it is too loose. If it feels like a solid ball, it is too tight and may jam. Aim for a feel similar to a tennis ball — firm with slight give.
What if the bobbin thread keeps breaking?
Check that the bobbin is wound evenly without lumps or loose spots. Make sure the thread is seated in the tension slot and the bobbin case door is latched. If the thread still breaks, the bobbin case may have a burr or rough spot — run your finger inside the case gently to feel for snags, or have the machine serviced.
Can I use any thread on the bobbin?
Use the same weight and type of thread on the bobbin as on the top. Mixing thread weights causes tension imbalance. Bobbin thread should be all-purpose polyester or cotton, the same as upper thread, unless your machine manual specifies otherwise.
Why does my bobbin keep falling out while I sew?
The bobbin case door is probably not latched all the way. Close it firmly until you hear or feel a click. If the door latches but the bobbin still falls out, the case may be damaged or the bobbin may be the wrong size — check your manual and replace the bobbin if needed.
How many bobbins should I have?
Keep at least three to five wound bobbins on hand. This way you can switch thread colors without stopping to wind a new bobbin. Store them in a small box or case to keep them clean and prevent thread from unraveling.