Thread the bobbin into the tension discs before you sew

A bobbin is the small spool that holds thread underneath your fabric. To load it, you wind thread onto an empty bobbin using your machine's winding mechanism, then insert the wound bobbin into the bobbin case — a metal or plastic housing under the needle plate. The thread must pass through the tension discs (two thin metal plates) so the machine can control how tight or loose the bottom thread sits. If you skip this step, your stitches will bunch or pucker.

This guide walks you through winding a bobbin, inserting it into the case, and threading it correctly. The process takes about three minutes once you know the steps.

Key Takeaways

  • Wind thread onto an empty bobbin using the bobbin winder on the right side of your machine, then snap the wound bobbin into the bobbin case under the needle plate.
  • Thread the bobbin thread through the tension discs by pulling it into the slot between them — this is the most common mistake people skip.
  • Singer machines have either a drop-in bobbin case (thread goes in from the top) or a removable case (you pull it out to load it), depending on your model.
  • If stitches look loose or bunched on the bottom of your fabric, the bobbin thread is usually not threaded through the tension discs correctly.

Wind thread onto an empty bobbin

Start with an empty bobbin — a small plastic or metal spool. Place it on the bobbin winder, a metal post on the right side of your machine near the top. Push the bobbin all the way onto the post until it clicks or sits snugly. The bobbin winder should be in the "out" position (away from the machine body) when you load it.

Take thread from your top spool (the one on the left side of the machine where you normally thread) and wrap it around the bobbin two or three times by hand, going clockwise. This anchors the thread so it winds evenly. Then guide the thread into the small notch or hook on the edge of the bobbin — this keeps the thread centered as it winds.

Press the foot pedal or press the start button (depending on your machine model) and let the bobbin wind. The machine will wind faster than you can by hand. Stop when the bobbin is full — most machines have a sensor that stops automatically, or you will see the thread pile up and slow down. Cut the thread and remove the bobbin by pushing it off the post.

Locate and open your bobbin case

Singer machines come in two types: drop-in bobbin machines and removable bobbin case machines. Drop-in models have the bobbin case built into the machine under the needle plate. Removable cases are a separate metal or plastic piece that you pull straight out.

To find your bobbin case, raise the presser foot (the metal arm that holds fabric down), then raise the needle to its highest point by turning the hand wheel toward you. This lifts the needle plate slightly and makes it easier to see underneath. If your machine has a removable case, you will see a small latch or lever on the left side of the case — pull it toward you and the case slides out. If you have a drop-in model, the case stays in place and you load the bobbin from the top.

Insert the wound bobbin into the case

For a drop-in bobbin machine, hold the wound bobbin with the thread tail pointing to the left. Lower it straight down into the case opening until it sits flat on the metal post in the center. The bobbin should spin freely when you flick it with your finger.

For a removable bobbin case, hold the case with the open side facing you. Insert the wound bobbin into the case the same way — thread tail to the left, bobbin sitting on the center post. The bobbin should not be tight; it should move slightly when you touch it. If it is stuck, remove it and check that the post is not bent.

Thread the bobbin through the tension discs

This step is where most people make mistakes. Look at the bobbin case and find the two thin metal plates on the left side — these are the tension discs. There is a slot or opening between them. Pull the bobbin thread up and to the left, then slide it into that slot so it sits between the two plates. You should hear or feel a slight click or resistance as the thread seats in the tension discs.

Pull the thread gently to make sure it is caught. If it slides out easily, it is not threaded correctly — try again. The thread must pass between the tension discs or your bottom stitches will be too loose. Once the thread is seated, you can trim the excess thread tail.

If you have a removable case, reinsert it into the machine by sliding it back in until you hear it click. Make sure the latch is fully closed.

Check your work before sewing

Before you start sewing, hold the fabric under the presser foot and lower the needle into it by turning the hand wheel. Lower the presser foot. Take the top thread (the one coming from the spool on the left) and pull it gently — you should feel resistance from the bobbin thread below. This means both threads are threaded correctly.

Sew a test seam on scrap fabric. Look at the bottom of the fabric. If the stitches look even and the thread is not bunched or loose, your bobbin is loaded correctly. If the bottom stitches look loose or the thread is bunched, the bobbin thread is usually not threaded through the tension discs — remove the bobbin case and thread it again.

Common mistakes and how to fix them

The most common error is forgetting to thread the bobbin through the tension discs. The bobbin sits in the case, but the thread does not pass between the tension plates. This makes bottom stitches look loose or causes thread to tangle. The fix is straightforward: remove the bobbin case, pull the bobbin thread into the tension disc slot, and try again.

Another mistake is winding the bobbin too full. If thread piles up unevenly on the bobbin, it will not sit flat in the case and may jam. Wind bobbins until they are full but not bulging. If you wound one too full, unwind some thread and try again.

A third issue is inserting the bobbin upside down or with the thread tail pointing the wrong way. The thread tail should point to the left when you look at the bobbin case from the front. If you insert it backward, the thread will not feed correctly. Remove it, flip it, and reinsert.

Frequently Asked Questions

Can I use a bobbin from a different brand in my Singer?

Some universal bobbins work in Singer machines, but the fit may be loose or tight. Singer bobbins are inexpensive and designed to work perfectly in your machine. Using the correct bobbin prevents jamming and uneven tension. Check your machine manual for the correct bobbin type — it is usually printed on the case or in the instruction booklet.

What if my bobbin keeps jamming or the thread breaks?

A jammed bobbin usually means the thread is not threaded through the tension discs, or the bobbin is wound too tightly and does not spin freely. Remove the bobbin, check that it spins easily, and rethread it through the tension discs. If the thread breaks while sewing, stop and rewind a fresh bobbin — a half-empty bobbin can cause tension problems.

How do I know when my bobbin is empty?

You will notice the bobbin is empty when stitches start to skip or the thread runs out mid-seam. Some Singer machines have a small window on the bobbin case so you can see the thread level. If you cannot see inside, wind a fresh bobbin before you start a large project so you do not run out halfway through.

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

No. The bobbin thread and top thread are separate. You only need to rewind and reload the bobbin when it runs out of thread. If you want to change the bobbin thread color, you can wind a new bobbin with a different color and swap it in — but you do not have to.