Sewing Machine Bobbin Jamming and Thread Bunching Up: What to Do

Read where the thread bunches

What you see, what it means, what to do

What you see	What it usually means	What to do
Bird’s nest, loops or tangling under the fabric; rattling noise	The top thread missed the tension discs or the take-up lever2,4	Cut the tangle free, then rethread the top with the presser foot raised2,4
Loops on top of the fabric	The bobbin is not inserted or threaded correctly (SINGER), or the upper tension is too tight (Brother)5,6	Reinsert and rethread the bobbin; then lower the upper tension if needed5,6
A tangle at the very start of the seam	The threads were not under the presser foot and toward the back4,8	Pull both threads under the foot, toward the back, before sewing4
Jams with thread caught in the hook	Upper threading, per SINGER’s 4452 manual1	Remove the upper thread and bobbin case, gently rock the handwheel and clear the bobbin area1
Jams or damage after changing bobbins	The wrong bobbin class5,6	Use the bobbin your machine takes4,6
Loops even when threading is right	JUKI: needle thread tension too loose, or a needle too thick or too fine for the fabric7	Adjust the upper tension; change the needle7

SINGER’s 6800C page calls it counter-intuitive: thread looping underneath “normally indicates that the upper thread is not correctly threaded.”⁸ The usual cause, per SINGER’s HD4552 manual, is a top thread that “is not correctly placed in the thread tension mechanism and has not been threaded through the take up lever”, so it says to rethread “making sure to first raise the presser foot lifter”.⁴ Kentucky’s guide: “Be sure that the thread passes correctly through the thread take up and upper tension disk(s).”¹¹

Free a jammed machine

Brother’s CS7000X manual gives the full method when fabric is caught. In short:²

1. “Immediately stop the machine.” Then turn it off.
2. Remove the needle. If it is down in the fabric, Brother says to turn the handwheel away from you (clockwise) to raise it first.
3. Remove the presser foot and its holder.
4. “Lift up the fabric and cut the threads below it.”
5. Remove the needle plate cover, “Cut out the tangled threads, and then remove the bobbin”, then the bobbin case.
6. Brush the lint out of the race. Brother: “Compressed can air is not recommended to be used.”
7. If the fabric is still stuck, free it from the needle plate; if you can’t, Brother says to contact an authorized service center.
8. Put the case and cover back, and turn the handwheel to check that the feed dogs move without touching the needle plate.
9. Fit a needle: “Since the needle may have been damaged when the fabric was caught in the machine, we recommend replacing it with a new one.”

Janome’s start guide says the same in short: cut the thread above and below the fabric, ease the fabric out while turning the handwheel slightly to raise the needle, and replace the needle if it is bent.³

Which way to turn the handwheel. In normal use, Brother’s CS7000X manual turns it toward you; it turns it away from you only in the step above, to lift a needle stuck in the fabric. SINGER’s help center allows only one direction on SINGER machines: “Always turn the handwheel TOWARDS you (counterclockwise)”, because the other way “may throw off the timing”.⁵ Yet SINGER’s own 4452 manual, for a jam, says to “Gently rock the handwheel backards and forwards” (the typo is in the manual).¹ Follow your machine’s manual.

The wrong bobbin

Bobbin classes look alike. SINGER: “Class 66, Class 15 and Class 15J bobbins are very similar. However, using the wrong type of bobbin in your machine can cause damage.”⁵ Brother’s XM2701 manual: “Only use the bobbin that comes with this machine or bobbins of the same type (part code: SA156, SFB: XA5539-151). Using other bobbins may cause damage to the machine.”⁶ Brother’s help adds: “You should be using a standard Class 15 bobbin.”¹²

SINGER’s bobbin guide gives three winding rules that prevent jams: “Wind thread on empty bobbins only”, “Don’t overfill bobbins or they will not move freely in the bobbin case”, and “The thread that is wound too loosely can cause machine jamming.”¹³ Replace a damaged bobbin: Brother lists “The bobbin is scratched or does not turn smoothly” with the fix “Replace the bobbin.”⁶

Lint under the needle plate

Brother: “Sewing performance will suffer if lint and dust collects in the bobbin case, therefore, it should be cleaned regularly.” Its steps for the CS7000X family: unplug, remove the presser foot and needle, remove the needle plate, take out the bobbin case and brush the race, and “Do not put oil on the bobbin case.”¹⁴ If the bobbin case keeps popping out, Brother says to clean it, check the bobbin and its winding, and “Check to see if the bobbin case is scratched or has a burr on it.”¹⁵