Threading a bobbin takes three steps: wind thread onto the bobbin, insert it into the bobbin case, and close the case

The bobbin is the small spool that holds thread underneath your fabric. It works together with the top thread to form a stitch. Most machines have a bobbin case — a metal or plastic housing that sits below the needle plate — and the bobbin slides into it. The exact steps depend on whether your machine has a removable bobbin case (older machines and many heavy-duty models) or a drop-in bobbin case (most modern machines). Both methods follow the same basic order: wind the bobbin first, then insert it, then close the case and pull the bobbin thread up through the needle plate.

The whole process takes about five minutes once you know where each part is. The most common mistake is skipping the final step — pulling the bobbin thread up through the needle plate — which leaves you with loose stitches and no idea why.

Key Takeaways

  • Wind the bobbin on your machine's winding post before you try to insert it into the bobbin case — an empty or partially wound bobbin will not catch thread correctly.
  • Most modern machines have a drop-in bobbin case on top of the needle plate; older machines and sergers often have a removable case that pulls straight out.
  • After inserting the bobbin, you must pull the bobbin thread up through the needle plate by turning the handwheel toward you — this is the step most people skip and then wonder why their stitches are loose.
  • If your bobbin case has a tension spring, the thread must sit in the spring's slot; if it sits on top of the spring, your stitches will be uneven.

Wind the bobbin before inserting it

Your machine's bobbin winder is usually on top of the machine, near the right side. Place an empty bobbin onto the winding post — a small metal or plastic rod that sticks up. The bobbin should slide on and sit flat against the post. Some machines have a small clip or collar that holds it in place; push that down after the bobbin is seated.

Bring the thread from your top spool down to the bobbin. Most machines have a guide or tension disc for the winding thread; thread the top thread through it, then wrap it around the bobbin two or three times by hand. Press the bobbin winder foot down (or engage the winder, depending on your machine model) and hold the thread end loosely. The bobbin will begin to spin and wind thread onto itself. The winder will stop automatically when the bobbin is full, or you can stop it manually when the bobbin looks evenly wound and full.

Cut the thread and remove the bobbin from the post. Set the bobbin winder foot back up or disengage the winder so the machine is ready to sew again. Do not try to insert a half-wound or empty bobbin into the bobbin case — it will not hold tension and your stitches will be loose or skip.

Locate and open your bobbin case

Most modern machines have a drop-in bobbin case. Raise the presser foot (the metal arm that holds fabric down), then lift the needle plate — the flat metal plate directly under the needle. The bobbin case is a small round or oval housing underneath, usually made of metal or clear plastic. You do not remove it; the bobbin drops straight into it from above.

Older machines and many sergers have a removable bobbin case. Look to the left side of the needle area for a small metal case with a latch or screw. Turn the latch counterclockwise or unscrew the case, then pull it straight toward you. The case will come free in your hand. Set it on a clean surface where you can see the tension spring inside.

Insert the bobbin into the case

For a drop-in case, hold the wound bobbin so the thread unwinds counterclockwise (the thread should come off the top of the bobbin as it sits in the case). Lower the bobbin straight down into the case opening. It will sit flat in the bottom. The thread end should be loose and hanging.

For a removable case, hold the bobbin the same way — thread unwinding counterclockwise. Drop the bobbin into the case so it sits flat on the bottom. The thread end hangs loose. Now look for the tension spring on the side of the case — it is a small metal piece that looks like a clip. Slide the thread under the spring and into its slot. The thread must sit in the slot, not on top of the spring. If the thread is on top of the spring, your bobbin tension will be too loose and stitches will be uneven.

Close the case and pull up the bobbin thread

If you have a removable case, slide it back into the machine from the left side until it clicks or seats fully. The latch should face outward. Turn the latch clockwise or tighten the screw to lock it in place. If you have a drop-in case, lower the needle plate back down over the bobbin case.

Now comes the step that most people forget: you must pull the bobbin thread up through the needle plate. Raise the presser foot. Hold the top thread (the one coming from your top spool) loosely in your left hand. Turn the handwheel (the large wheel on the right side of the machine) toward you one full rotation. The needle will go down and come back up. As it comes up, it will catch the bobbin thread and pull a loop of it up through the needle plate. Gently pull on the top thread and the bobbin thread loop will come up with it. You should now see both threads lying on top of the needle plate, ready to thread through the needle.

Check tension and test before sewing

Before you start sewing on your project, run a test on scrap fabric. Use two layers of the same fabric you plan to sew. Thread both the top and bobbin with the same color thread so you can see any tension problems clearly. Sew a few inches of straight stitches and look at both sides of the fabric. The stitches should look the same on top and bottom — the thread should not bunch or loop on either side.

If the top thread is loose and the bobbin thread is tight, the bobbin tension is too tight. If the bobbin thread is loose and the top thread is tight, the bobbin tension is too loose. Most machines have a small screw on the bobbin case that adjusts tension, but the adjustment is small — usually a quarter turn at a time. If you are not sure how to adjust it, check your machine's manual or contact the manufacturer, because turning the screw the wrong way can make the problem worse.

Frequently Asked Questions

Which direction should the thread unwind from the bobbin?

The thread should unwind counterclockwise as the bobbin sits in the case. This means if you hold the bobbin in your hand and look at it straight on, the thread comes off the top and to the left. If the thread unwinds the wrong way, the bobbin will not catch tension correctly and your stitches will be loose.

What if the bobbin thread does not come up through the needle plate?

Turn the handwheel again — sometimes one rotation is not enough. Hold the top thread gently and turn the wheel toward you two or three times. If the bobbin thread still does not appear, check that the bobbin is wound tightly and fully, that it is inserted correctly into the case, and that the thread is in the tension spring slot (if your machine has a removable case).

Can I use a plastic bobbin in a machine that came with a metal bobbin?

Check your machine's manual first. Some machines are designed for one type only. If you use the wrong type, the bobbin may not sit flat in the case or may not wind evenly. Most modern machines accept both, but older machines often do not.

How often should I wind a new bobbin?

Wind a new bobbin whenever the current one runs out of thread or when you are changing thread colors. A bobbin that is only half full can work, but it will run out faster and may cause tension problems if it is too light.

Why does my bobbin keep coming loose from the winding post?

The bobbin may not be seated all the way down on the post, or the post itself may be worn. Push the bobbin down firmly until it sits flat against the base of the post. If it still spins loose, the post may need replacement — contact the machine manufacturer for a replacement post.