The bobbin goes in the bobbin case, which sits below the needle plate

The bobbin is the small spool that holds the thread for the underside of your seam. It lives in a bobbin case — a metal or plastic housing that sits directly under the needle plate (the flat metal surface your fabric rests on). To thread your machine correctly, you need to wind thread onto the bobbin first, then place the wound bobbin into the case so the thread feeds up through a tension spring and into the needle area.

The exact steps depend on whether your machine has a drop-in bobbin case (you drop the bobbin straight down into a hole) or a removable bobbin case (you lift out a metal case, insert the bobbin, and slide it back in). Most modern home machines use the drop-in style. Check your machine's manual to confirm which type you have — the manual will also show you a diagram of your specific bobbin case, which matters because the thread path varies slightly between machines.

Key Takeaways

  • Wind the bobbin on your machine's bobbin winder before you insert it — an empty or partially wound bobbin will cause loose stitches.
  • The bobbin sits in a case directly under the needle plate; most modern machines have a drop-in case you access by lifting the plate.
  • The thread must pass through the tension spring on the bobbin case, not around it, or your bottom thread will be too loose.
  • If your machine has a removable bobbin case, the case itself has a small lever or hook that holds the thread in the tension spring — check your manual for the exact position.

Winding the bobbin before you insert it

You cannot use an empty bobbin. Your machine has a bobbin winder — a spindle on the side or top of the machine where you wind thread onto the bobbin before it goes into the case. Place an empty bobbin on the winder spindle, thread the machine's bobbin winder (follow the path shown in your manual), and press the foot pedal or press a button (depending on your machine) until the bobbin is full. The winder will stop automatically when the bobbin is wound tight.

Wind the bobbin with the same thread color you are using on top, or use a neutral color like white or gray. If you wind it too loosely, your bottom stitches will be loose. If you try to use a bobbin that is only half-wound, the thread will run out mid-seam. Most sewers wind several bobbins at once so they have backups ready.

Accessing the bobbin case on a drop-in machine

On a drop-in bobbin machine, the bobbin case is hidden under the needle plate. Raise the presser foot (the metal arm that holds fabric down), then lift the needle plate by hand or by pressing a release button — your manual will show which. The bobbin case is the small metal or plastic cup sitting in the hole underneath.

You do not remove the case itself on a drop-in machine. Instead, you drop the wound bobbin directly into the case from above. The bobbin sits on a small spindle inside the case, and the case has a slot or notch where the thread feeds out. Before you insert the bobbin, look at the case and find the tension spring — a small metal arm or wire that sticks out slightly. This spring holds the thread and controls how tight the bottom stitches are.

Threading the bobbin through the tension spring

This is the step that causes most problems. Once the bobbin is sitting on the spindle inside the case, pull the thread end up and to the side, then slide it into the slot or notch in the bobbin case. The thread must pass through the tension spring — meaning it goes between the spring and the case body — not around the outside of the spring. If the thread sits outside the spring, your bottom stitches will be loose and uneven.

Pull the thread gently to make sure it is seated in the spring. You should feel a slight resistance, which means the spring is holding the thread. Leave a 4- to 6-inch tail of thread hanging out of the case. This tail will be pulled up through the needle area when you raise the presser foot, and you will hold both thread tails while you take your first few stitches.

Reinserting the needle plate and raising the presser foot

Once the bobbin is threaded through the tension spring, lower the needle plate back down and press it gently until it clicks or seats flush. Raise the presser foot by lifting the lever on the back of the machine. Raising the presser foot opens the tension discs on the top thread path, which allows the top thread to feed down and hook around the bobbin thread.

Now thread the top of the machine as usual — feed the thread through the guides, tension discs, and needle. Hold both the top thread and the bobbin thread tail in your hand, take one stitch by hand or by pressing the needle-down button, and the bobbin thread will be pulled up through the needle plate. You can then trim both thread tails and begin sewing.

Removing and reinserting a removable bobbin case

If your machine has a removable bobbin case (older machines and some specialty machines), the case is a separate metal piece that slides out of the machine. To remove it, locate the small lever or latch on the case and pull it toward you. The case will slide out of its slot. Set it on a clean surface — do not drop it, as the tension spring can bend.

Place the wound bobbin on the spindle inside the case, then thread the bobbin thread through the tension spring. The thread path is the same as on a drop-in machine: the thread must pass between the spring and the case body. Once the thread is seated, slide the case back into the machine until you hear or feel it click into place. The lever should point toward the back of the machine when the case is fully inserted.

Troubleshooting loose or tight bottom stitches

If your bottom stitches are loose and loopy, the bobbin thread is not under enough tension. Check that the thread is actually passing through the tension spring, not sitting outside it. Also check that the bobbin is wound tightly — if it is loose or uneven, wind a new one. If the thread is threaded correctly and the bobbin is wound well, the tension spring itself may be bent or dirty; a small amount of lint can prevent the spring from gripping the thread.

If your bottom stitches are too tight, the bobbin thread may be wound too tightly, or the tension spring may be gripping too hard. Try winding a new bobbin at a slightly slower speed. If the problem continues, the tension spring may need adjustment — this is a job for a technician, as adjusting the spring requires a small screwdriver and knowledge of how much to turn it.

Frequently Asked Questions

Can I use a bobbin from a different brand of machine?

No. Bobbins are not universal. Each machine brand and sometimes each model uses a specific bobbin size and shape. Using the wrong bobbin can jam the case or cause the thread to slip. Buy bobbins made for your machine brand — check your manual for the part number, or bring your machine to a fabric store and match the bobbin to your machine model.

What if the bobbin thread keeps breaking?

A breaking bobbin thread usually means the bobbin is wound too tightly, the thread is not threaded through the tension spring, or the bobbin case is dirty or has a burr. First, wind a new bobbin at normal speed and rethread it through the tension spring. If it still breaks, use a small brush or cotton swab to clean out the bobbin case — lint and dust can catch the thread. If the case has a rough spot or burr, have a technician smooth it.

Do I need to rewind the bobbin every time I change thread color?

Yes, if you want the bottom thread to match the top thread. You can use a bobbin wound with a different color, but it will show on the underside of your seam. Many sewers keep several bobbins wound with their most-used colors — white, black, and neutral gray — so they do not have to rewind for every project.

Why does my bobbin keep falling out of the case?

The bobbin spindle inside the case may be worn or bent, or the bobbin itself may be the wrong size. Try a new bobbin first — if it stays in place, the old one was damaged. If a new bobbin also falls out, the spindle may be worn and the case may need to be replaced. Contact your machine's manufacturer or a repair technician for a replacement case.