Threading a bobbin takes three steps: wind thread onto the bobbin, insert it into the case, and pull the thread through the tension spring
A bobbin is the small spool that holds thread underneath your fabric. If your bobbin is not threaded correctly, your stitches will loop, bunch, or break. The process is straightforward once you know where each part sits and in what order to move them.
Singer machines vary slightly by model, but the bobbin area works the same way on most machines made in the last 40 years. This guide covers the standard method used on drop-in bobbins (the kind that sit in a case on top of the needle plate) and front-loading bobbins (the kind that slide into a case on the front of the machine). Check your machine's manual if you have a top-loading bobbin, as the threading path differs.
Key Takeaways
- Wind thread onto a blank bobbin using the bobbin winder on the side of your machine, then cut the thread and remove the full bobbin.
- Insert the wound bobbin into the bobbin case with the thread running under the tension spring, then pull the thread tail through the slot.
- Drop the bobbin case back into the machine and close the cover plate so the case clicks into place.
- Pull up the bobbin thread by turning the handwheel toward you once while holding the top thread, so both threads sit in the needle area.
Wind thread onto a blank bobbin
Start with an empty bobbin (a small plastic or metal spool). Place it on the bobbin winder, which is a small post on the right side of your machine, near the top. Push the bobbin all the way onto the post until it sits flush.
Take thread from your top spool and wrap it around the bobbin two or three times by hand, going clockwise. This anchors the thread so it winds evenly. Then press the bobbin winder against the machine body — this engages the winder and disengages the needle. Turn the handwheel toward you (or press the foot pedal gently if your machine has an electric winder) until the bobbin is full. The machine will stop automatically when the bobbin reaches capacity, or you can stop it yourself when the bobbin looks full but not overstuffed. Cut the thread and remove the bobbin.
Open the bobbin case and insert the wound bobbin
Raise the presser foot (the metal arm that holds fabric down). This opens the tension discs on the top of the machine and makes it easier to work with the bobbin case. Locate the bobbin case — on most Singer machines, it sits under the needle plate in a drop-in style, or on the front of the machine in a front-loading style.
For a drop-in bobbin, lift the needle plate or the small hinged cover above it. You will see a metal or plastic case with a small hook. For a front-loading bobbin, open the small door on the front of the machine. Pull the bobbin case out gently — it should slide or lift free without force.
Thread the bobbin through the tension spring
Hold the wound bobbin with the thread tail pointing toward you. Look at the bobbin case — you will see a small metal or plastic spring on one side. This is the tension spring, and it controls how tight the bobbin thread pulls.
Insert the bobbin into the case so it sits flat and centered. Pull the thread tail under the tension spring (the thread should slide under the curved metal part). Then pull the thread tail through the small slot or notch on the opposite side of the case. The thread should now be held snugly by the spring, with the tail sticking out of the slot. If the thread is not under the spring, the tension will be wrong and your stitches will be loose or uneven.
Return the bobbin case to the machine
Slide or drop the bobbin case back into the machine. For drop-in bobbins, lower it into the space under the needle plate until it clicks or sits flat. For front-loading bobbins, push the case back into the door until you hear or feel it lock. Close the needle plate cover or the front door. The case should not move or rattle — if it does, remove it and reinsert it.
Leave the bobbin thread tail hanging out of the case. Do not try to tuck it in or hide it yet.
Bring the bobbin thread up to the needle area
Hold the top thread (the one coming from the spool at the top of the machine) loosely in your left hand. Turn the handwheel toward you with your right hand one full rotation. As you turn, the needle will go down and come back up, and it will catch the bobbin thread and pull it up through the needle plate.
When the needle comes back to the top, you should see a loop of bobbin thread near the needle. Use a seam ripper or small hook to pull this loop up and out. Now both the top thread and the bobbin thread should be sitting above the needle plate, with their tails pointing toward the back of the machine. Pull both tails toward the back and under the presser foot, then trim them short with scissors.
Test the tension before sewing
Sew a test seam on scrap fabric using the same weight fabric and thread you plan to use for your project. Look at the stitches on both sides. If the top thread is loose and loopy on the underside, the bobbin tension is too tight — remove the bobbin case and loosen the small screw on the case slightly (turn it counterclockwise about one-quarter turn). If the bobbin thread is loose and loopy on the top side, the bobbin tension is too loose — tighten the screw slightly (turn it clockwise). Make small adjustments and test again.
Most Singer machines come with the bobbin tension set correctly from the factory, so you should not need to adjust it unless you change thread weight or type. If you do adjust the screw, write down the original position so you can return to it if needed.
Frequently Asked Questions
What if the bobbin thread breaks while I am sewing?
Stop sewing when ready and raise the presser foot. Remove the bobbin case and check that the thread is still under the tension spring and through the slot. If the thread has slipped out, rethread it. If the thread is frayed or kinked, remove the bobbin and wind a new one. Reinsert the case and bring the bobbin thread up again before continuing.
Can I use a metal bobbin instead of plastic?
Check your machine manual — some Singer models require plastic bobbins, while others work with both. Using the wrong type can cause tension problems or damage the bobbin case. If your manual does not specify, stick with the bobbin type that came with your machine.
How full should the bobbin be?
Wind the bobbin until it is full but not bulging. A bobbin that is too full can jam in the case or cause uneven tension. A bobbin that is too empty will run out of thread mid-seam. Most bobbins have a line or edge that shows when they are full enough.
Why does my bobbin thread keep coming loose?
The thread may not be under the tension spring, or it may have slipped out during sewing. Remove the bobbin case, check that the thread is seated under the spring, and reinsert the case. If this happens repeatedly, the tension spring may be bent or worn — contact a Singer dealer or repair shop to have it checked.
Do I need to rewind the bobbin every time I change thread color?
Yes. If you switch to a different thread color, wind a new bobbin with that color. Leaving the old color in the bobbin will show on the underside of your seams and may look messy. Keep several bobbins wound with colors you use often so you always have one ready.