The bobbin goes into the bobbin case, which sits under the needle plate

A bobbin is a small spool that holds the lower thread in your Singer machine. To use it, you wind thread onto the bobbin using your machine's winding mechanism, then insert the wound bobbin into the bobbin case — a metal or plastic housing that sits directly under the needle plate (the flat metal plate the presser foot sits on). The bobbin case is where the magic happens: the upper thread and lower thread lock together to form a stitch.

Most Singer machines use one of two bobbin systems: a drop-in bobbin that sits in a case you remove from under the needle plate, or a front-loading bobbin that slides into a case that stays permanently in place. The steps differ slightly between the two, but the principle is the same.

Key Takeaways

  • Wind your bobbin on the bobbin winder first — an empty bobbin will not create stitches.
  • The bobbin case sits under the needle plate and must be removed or opened to access the bobbin slot.
  • Thread the bobbin through the tension spring inside the case so the thread sits in the correct groove.
  • Leave about 4 inches of thread tail hanging out before you close the case or slide it back into place.
  • If your machine skips stitches or loops thread, the bobbin is often wound too loosely or threaded incorrectly through the tension spring.

Locate and remove the bobbin case (drop-in models)

If your Singer has a drop-in bobbin system, the bobbin case is a removable metal or plastic piece that sits directly under the presser foot. To access it, raise the presser foot (this opens the tension discs on the upper threading path), then look under the needle plate. You will see a small latch or lever on the bobbin case — usually on the left side.

Gently pull the latch toward you or lift the lever, and the entire bobbin case will slide out toward you. Set it on a clean surface where you can see it clearly. Do not force it; if it does not slide smoothly, check that the presser foot is fully raised and that nothing is blocking the case.

Open the bobbin case (front-loading models)

Front-loading bobbins are built into machines like the Singer Heavy Duty or Quantum series. Instead of removing the case, you open a small hinged door on the front of the machine. Raise the presser foot, then look for a small metal or plastic door on the front of your machine's body, usually just below the needle area.

Press the release button or lever (usually marked with an arrow) and the door will swing open, revealing the bobbin case inside. You do not remove anything — you straightforward work with the case in place. This design is faster because you never have to take the case out.

Insert the wound bobbin into the case

Hold your wound bobbin with the thread tail pointing upward and to the left. Slide the bobbin into the slot in the bobbin case — it should sit flat and spin freely. The bobbin will only fit one way, so if it does not slide in smoothly, rotate it 180 degrees and try again.

Once the bobbin is seated, you will see a small tension spring inside the case — a thin metal piece that looks like a curved bracket. Pull the thread tail down and to the left, then tuck it under this tension spring. The thread should sit snugly in the groove of the spring, not just resting on top of it. This tension spring controls how much resistance the lower thread has, just as the upper tension dial controls the upper thread.

Leave thread hanging and close the case

Before you close the bobbin case, pull the thread tail so about 4 inches hangs out of the case. This tail is important: when you start sewing, you will hold both the upper and lower thread tails to prevent the machine from pulling the bobbin thread up into the needle area, which can cause tangles or broken thread.

For drop-in cases, slide the case back into the machine until you hear or feel a click, then push the latch or lever back into place. For front-loading cases, straightforward close the hinged door until it latches. The door should sit flush with the machine body — if it does not close all the way, the bobbin case may not be seated correctly, and you should open it and reseat the bobbin.

Thread the upper thread and test the tension

Now that the bobbin is in place, thread the upper thread through your machine's needle threading path as you normally would. Raise the presser foot (this opens the tension discs), thread the needle, and lower the presser foot again.

Hold both the upper thread and the bobbin thread tail in your left hand, then turn the handwheel toward you (away from your body) one full rotation. This brings the needle down and back up, and locks the bobbin thread. You should see a loop of upper thread come up through the needle plate — grab it with tweezers and pull it up gently. Now you have both threads above the needle plate, and you are ready to sew.

Troubleshoot if the bobbin is not working

If your machine skips stitches, loops thread on the back, or breaks thread, the bobbin is often the culprit. First, check that the bobbin is wound evenly and tightly. A bobbin wound too loosely or unevenly will not feed thread at a consistent tension, and stitches will suffer. If the bobbin looks correct, remove it and rewind it using your machine's bobbin winder.

Second, check that the thread is seated correctly in the tension spring. Remove the bobbin case, pull the thread out, and rethread it under the tension spring, making sure it sits in the groove and not just on top of the spring. Third, make sure the bobbin case itself is not damaged — if the tension spring is bent or the case has cracks, it may not hold tension correctly, and you will need to replace the case. Singer sells replacement bobbin cases for most models, and they are inexpensive.

Frequently Asked Questions

What kind of bobbin do I need for my Singer?

Singer makes several bobbin styles, and the wrong one will not fit your machine. Check your machine's manual or the bobbin case itself — it usually has the bobbin type printed on it. Class 15 bobbins are the most common for home machines. Buy bobbins from a fabric store or online, and buy a few extras so you always have a wound one ready.

Can I use a plastic bobbin instead of metal?

Yes, if your machine is designed for plastic bobbins. Some Singer models come with plastic bobbins, others with metal. Metal bobbins are more durable and hold their shape longer, but plastic works fine if that is what your machine uses. Do not mix types — use what came with your machine or what the manual recommends.

Why does my bobbin thread keep breaking?

Bobbin thread breaks when it is wound too tightly, when the tension spring is bent or misaligned, or when the bobbin case has a burr or rough spot inside. Check the bobbin winding first — it should be firm but not so tight you cannot turn the bobbin by hand. If winding is fine, inspect the tension spring and the inside of the case for damage. A small burr can be smoothed with fine sandpaper, but a cracked case must be replaced.

Do I have to remove the bobbin case every time I change the bobbin?

Only if you have a drop-in system. Front-loading machines let you open the door and swap the bobbin without removing the case. Drop-in systems require you to pull the case out each time, but it takes only a few seconds once you have done it a few times. Keep the case in a safe spot while you work — do not set it down where it can roll away or get lost.

What happens if I put the bobbin in upside down?

The bobbin will not spin correctly, and the machine will not feed thread smoothly. You may hear grinding or clicking sounds, or the thread may not feed at all. If this happens, stop sewing when ready, remove the bobbin case, and check that the bobbin is seated correctly with the thread tail pointing upward and to the left. Putting it in backwards will not damage the machine, but it will not work.