The basic steps to load a bobbin
A bobbin is the small spool that holds the lower thread in your sewing machine. To insert it, you first need to open the bobbin case — usually a hinged or removable compartment on the front or side of your machine, depending on your model. Consult your machine's manual to find the exact location, as this varies widely.
Once the case is open, you'll see a metal or plastic bobbin holder with a small hook or slot. Place your wound bobbin onto the spindle (the metal post in the center of the holder) so it sits flat and find. The bobbin should spin freely when you give it a gentle push. Close the case firmly until you hear or feel it click into place. That's the mechanical part done — but there's one more critical step that many beginners skip.
Key Takeaways
- The bobbin goes onto the spindle inside the bobbin case, which is usually located on the front or bottom of your machine.
- After closing the bobbin case, you must thread the bobbin thread through the tension spring or slot — skipping this step causes loose stitches on the underside of your fabric.
- The bobbin thread should be wound tightly and evenly on the bobbin; if it's loose or uneven, rewind it before inserting it.
- Most machines require you to raise the presser foot lever before threading the bobbin, because this opens the tension discs that the thread must pass through.
Threading the bobbin thread through the tension spring
After you've placed the bobbin in its case and closed the cover, look for a small metal spring or a slot marked on the bobbin case itself. This is the bobbin tension spring, and the thread must pass through it. Gently pull the bobbin thread so it sits in this spring or slot — you should feel a slight resistance, which means the thread is properly tensioned.
If you skip this step, your bottom stitches will be loose and loopy, even if your top thread tension is perfect. This is one of the most common mistakes beginners make. The thread should lie flat in the spring, not twisted or bunched. If it doesn't sit smoothly, remove the bobbin, rewind it if necessary, and try again.
Winding the bobbin correctly before insertion
Before you can insert a bobbin, it needs to be wound with thread. Most machines have a bobbin winder on the side or top of the machine. Place an empty bobbin on the winder spindle, then guide your thread through a tension disc on the winder itself (this is different from the machine's main tension). Wind slowly at first to seat the thread, then increase speed once the bobbin is turning evenly.
Stop winding when the bobbin is full — the thread should reach the edge of the bobbin but not overfill it. An overfilled bobbin won't fit properly in the case, and an underfilled one will run out mid-project. Most machines have an automatic shutoff that stops the winder when the bobbin is full, so listen for that click. If your machine doesn't have this feature, watch carefully and stop by hand when the bobbin looks full.
Raising the presser foot before threading
Before you thread the bobbin thread through the tension spring, raise your presser foot lever (the lever at the back of the machine that holds fabric in place). This step opens the tension discs inside the machine, allowing the thread to pass through them smoothly. If you try to thread the bobbin with the presser foot down, the thread won't seat properly in the tension spring, and you'll have tension problems.
This is straightforward to forget because you're focused on the bobbin case, which is physically separate from the presser foot. But the two are mechanically linked. After you've threaded the bobbin thread and closed the bobbin case, you can lower the presser foot again before you start sewing.
Common mistakes and how to avoid them
The most frequent error is forgetting to thread the bobbin thread through the tension spring. You'll notice this when ready when you start sewing — the underside of your fabric will have loose, loopy stitches while the top looks normal. If this happens, stop, raise the presser foot, open the bobbin case, and guide the thread into the spring.
Another common mistake is winding the bobbin too tightly or too loosely. A bobbin wound too tightly can break the thread or cause tension problems. One wound too loosely will run out of thread quickly and create uneven stitches. Wind at a moderate, steady speed and stop when the bobbin reaches its full line.
A third mistake is inserting the bobbin backwards or upside down. The wound thread should unwind from the top of the bobbin as it spins, not from the bottom. If you're unsure which way is correct, check your manual — most machines have a diagram showing the proper orientation.
Checking your work before you sew
After you've inserted the bobbin and threaded the top thread, do a quick test before you start a real project. Place a scrap of fabric under the presser foot, lower the foot, and sew a few stitches. Look at both the top and bottom of the fabric. The top stitches should be even and tight, and the bottom stitches should match in tension — not loose or loopy.
If the bottom stitches are loose, stop and check that the bobbin thread is seated in the tension spring. If the top stitches are loose, adjust your top thread tension (usually a dial on the front of the machine). If both look uneven, the bobbin may be wound unevenly — rewind it and try again. A few minutes of testing now saves frustration later.
Different bobbin types and how they fit
Not all bobbins are the same. Some machines use class A bobbins (plastic, with a large center hole), while others use class L bobbins (metal or plastic, with a smaller hole). A few older or specialty machines use proprietary bobbins that fit only that model. Using the wrong bobbin type won't fit properly in the case and can damage your machine.
Check your manual to find out which type your machine uses, and buy extras of the correct type. Many fabric stores and online retailers sell bobbins by machine brand and model. If you're unsure, bring your machine's model number to a fabric store and ask — staff can identify the right bobbin in seconds. Keeping a few wound bobbins on hand means you won't run out mid-project.
Frequently Asked Questions
What happens if I don't thread the bobbin thread through the tension spring?
Your bottom stitches will be loose and loopy while your top stitches look normal. This is because the bobbin thread isn't being tensioned properly. Stop sewing, raise the presser foot, open the bobbin case, and guide the thread into the spring. Then test on scrap fabric before continuing.
Can I use any bobbin in my machine?
No. Your machine uses a specific bobbin type — usually class A or class L — and using the wrong type can jam the case or damage the machine. Check your manual or machine model number to find the correct type. Buying the wrong bobbins is a common and frustrating mistake, so verify before you purchase.
How do I know if my bobbin is wound too tightly?
A bobbin wound too tightly may break the thread when you try to unwind it, or it may cause tension problems during sewing. Wind at a moderate, steady speed and stop when the bobbin reaches the full line on the case. If you're unsure, rewind it at a slightly slower speed.
Why does my bobbin keep coming loose in the case?
The bobbin may not be seated fully on the spindle, or the case may not be closing completely. Remove the bobbin, place it on the spindle again, and make sure it sits flat and centered. Then close the case firmly until you hear or feel it click. If the case still won't close, the bobbin may be the wrong type for your machine.
Do I need to rewind my bobbin every time I run out of thread?
Yes. When the bobbin runs out, you'll notice the thread stops feeding. Remove the empty bobbin, wind a fresh one, and insert it following the same steps. Having several wound bobbins ready means you can swap them quickly without stopping your project.