Thread bunching underneath your fabric is often called bird nesting.
It is the tangled mass of thread that can appear beneath a seam, sometimes after only a few stitches. It may look alarming, but it is one of the most common problems beginner sewists experience and is usually caused by something simple.
Our Sewing for beginners guide covers the most common mistakes new sewists can make.
The most important thing to remember is this: although the tangle appears underneath the fabric, the problem is often connected to the upper thread rather than the bobbin.
Before changing the tension or assuming your sewing machine needs repairing, work through the checks in this guide in order.
What Is Bird Nesting?
Bird nesting happens when loose loops of thread collect underneath the fabric while you sew.
You may notice:
- A thick knot of thread beneath the seam.
- Loose loops on the underside of the fabric.
- The fabric becoming trapped beneath the presser foot.
- The machine making a sudden clunking or straining sound.
- The upper thread breaking.
- The handwheel becoming difficult to turn.
Continuing to press the foot pedal rarely solves the problem. It normally creates a larger tangle and makes the fabric more difficult to remove.
Why Does Thread Bunch Underneath the Fabric?
The stitch is formed by the upper thread and bobbin thread working together.
If the upper thread does not pass correctly through the tension system, the machine cannot control it properly. Excess thread is then pulled beneath the fabric, where it forms loose loops and tangles around the bobbin area.
Common causes include:
- The machine was threaded with the presser foot lowered.
- The upper thread missed a guide or the take-up lever.
- The thread is caught around the spool or spool pin.
- The bobbin is inserted incorrectly.
- The bobbin is wound unevenly.
- The wrong bobbin type is being used.
- The thread tails were not held at the beginning of the seam.
- The presser foot was not lowered before sewing.
- The needle is bent, blunt or unsuitable for the fabric.
1. Stop Sewing Immediately
When you hear an unusual sound or feel the fabric stop feeding, take your foot off the pedal.
Do not continue sewing in the hope that the tangle will clear by itself. More stitches usually add more thread to the knot.
Raise the needle to its highest position using the handwheel. Always turn the handwheel in the direction recommended by your sewing-machine manual, which is usually towards you on a domestic machine.
Raise the presser foot and remove the fabric carefully. If the fabric will not move, do not pull it forcefully.
Use small scissors or thread snips to cut the tangled threads beneath the fabric. Remove the fabric gently once the threads have been released.
2. Clear Loose Thread from the Bobbin Area
Remove the bobbin cover, bobbin and bobbin case where appropriate.
Check the area for:
- Loose thread ends.
- Small pieces of tangled thread.
- Lint and fluff.
- A thread wrapped around the bobbin case.
- A damaged or distorted bobbin.
Remove loose material carefully using the brush supplied with your machine or another suitable soft brush.
Do not blow into the machine because this can push lint and moisture further inside.
Reassemble the bobbin area according to the sewing-machine manual before testing the machine again.
3. Rethread the Sewing Machine
Remove the upper thread completely and thread the machine again from the beginning.
Do not simply pull the thread back through one or two guides. Starting again makes it easier to spot a missed step.
Raise the Presser Foot Before Threading
Always raise the presser foot before threading the upper part of the sewing machine.
On many domestic machines, raising the presser foot opens the tension discs. This allows the thread to sit properly inside the tension system.
If the presser foot is lowered during threading, the thread may remain outside the tension discs. The machine can then pull large amounts of loose thread beneath the fabric.
Raise the Take-Up Lever
Turn the handwheel until the needle and take-up lever are at their highest positions.
The take-up lever is an important part of the upper threading route. If the thread misses it, the machine may create loose stitches, broken thread or a bird’s nest beneath the fabric.
Follow Every Thread Guide
Follow the numbered threading route shown on your machine or in the manual.
Check that the thread:
- Leaves the spool smoothly.
- Passes through the first thread guide.
- Sits properly between or inside the tension discs.
- Passes through the take-up lever.
- Runs through the remaining guides.
- Passes through the needle-bar guide.
- Enters the needle in the correct direction.
If the machine was sewing correctly before the thread was changed, compare the new threading route carefully with the machine manual.
4. Check the Thread Spool
Make sure the upper thread can leave the spool without catching.
Check that:
- The spool is fitted in the correct direction.
- The spool cap is suitable for the spool size.
- The thread is not trapped beneath the spool cap.
- The thread is not wrapped around the spool pin.
- A small notch on the spool is not catching the thread.
- The thread is not tangled before it reaches the first guide.
A thread that catches intermittently can create uneven tension and sudden stitching problems.
If the spool has a rough or damaged edge, turn it around where appropriate or try a different spool.
5. Check the Bobbin
The problem is often caused by the upper thread, but the bobbin should still be checked carefully.
Make sure the bobbin is:
- Wound evenly.
- Inserted in the correct direction.
- The correct type for the sewing machine.
- Properly seated in the bobbin case or compartment.
- Threaded through the correct bobbin guide or tension slot.
Use the Correct Bobbin Type
Bobbins that look almost identical are not always interchangeable.
A bobbin that is slightly too tall, too narrow or the wrong shape may not rotate properly. Check the machine manual or the manufacturer’s guidance before buying replacements.
Check the Winding
The thread should be wound smoothly and evenly across the bobbin.
Do not use a bobbin that is:
- Loosely wound.
- Overfilled.
- Wound heavily on one side.
- Crossed with loose loops.
- Cracked, bent or chipped.
Rewind the bobbin if necessary rather than trying to sew with an unevenly wound one.
Insert It in the Correct Direction
Different machines require the bobbin thread to unwind in different directions.
Use the diagram beside the bobbin compartment or follow the instructions in the manual. Pull the thread through the required slot and guide before replacing the cover.
6. Check the Sewing-Machine Needle
A damaged or unsuitable needle can interfere with stitch formation and contribute to thread tangles.
Check that the needle is:
- Straight and undamaged.
- Inserted fully into the needle clamp.
- Facing the correct direction.
- Tightened securely.
- The correct type for the fabric.
- The correct size for the fabric and thread.
Replace the needle if you are unsure about its condition. A fresh needle is a quick and inexpensive troubleshooting step.
7. Hold Both Thread Tails
Before beginning the seam, place the upper thread and bobbin thread underneath and behind the presser foot.
Hold both thread tails gently for the first few stitches, then release them.
This helps prevent the loose ends from being pulled down through the needle plate and becoming tangled beneath the fabric.
How to Bring Up the Bobbin Thread
- Hold the upper thread gently with your left hand.
- Turn the handwheel towards you for one complete stitch.
- Pull the upper thread to bring the bobbin-thread loop through the needle plate.
- Pull both thread tails beneath and behind the presser foot.
Some modern machines manage the thread tails automatically, but holding them can still be useful when sewing lightweight fabric or starting close to an edge.
8. Lower the Presser Foot
Always lower the presser foot before you begin sewing.
When the presser foot is raised, the tension discs may remain open. The machine may then feed loose upper thread underneath the fabric instead of forming controlled stitches.
Lowering the presser foot also allows the feed dogs and presser foot to hold the fabric properly as it moves through the machine.
If your machine refuses to sew or displays an error when the foot is raised, treat that warning as a useful reminder rather than trying to override it.
9. Start Sewing Slowly
Begin the seam at a controlled speed.
Starting slowly gives the first stitches time to form correctly and allows you to stop quickly if the thread begins tangling again.
Watch and listen for:
- A smooth, even sewing sound.
- Fabric feeding normally.
- Balanced stitches on both sides.
- No loose loops appearing underneath.
- No pulling or catching from the upper spool.
There is no need to press the pedal fully. Slow, controlled sewing is much easier to monitor.
10. Test on a Scrap of Fabric
Do not return immediately to the project pieces.
Use a scrap of the same fabric and test several centimetres of stitching.
Where possible, test:
- The same number of fabric layers.
- The same interfacing or wadding.
- The same thread.
- The same needle.
- The same stitch length.
Check the top and underside of the test seam. The stitches should lie flat and balanced without loose loops or knots.
If the machine stitches correctly on the scrap, you can return to the main project with more confidence.
Should You Adjust the Thread Tension?
Do not adjust the tension first.
Bird nesting is commonly caused by incorrect threading, a missed take-up lever, an incorrectly inserted bobbin or sewing with the presser foot raised.
Changing the tension before checking these basics may create an additional problem. Our guide Sewing for Beginners common mistakes covers this and fabric choice, needle sizes and much more.
Only consider adjusting the tension after you have:
- Rethreaded the upper thread with the presser foot raised.
- Checked the bobbin type, winding and insertion.
- Fitted a suitable needle.
- Used good-quality thread.
- Tested the machine on a fabric scrap.
If the machine was stitching correctly before the problem began, leave the standard tension setting alone while completing the basic checks.
Check the Thread Quality
Old, damaged or poor-quality thread can snap, shred and create inconsistent stitches.
Inspect the thread for:
- Visible fluff.
- Uneven thickness.
- Weak or brittle sections.
- Knots.
- Damage caused by poor storage.
Try a dependable all-purpose sewing thread if you are unsure whether the current spool is contributing to the problem.
The upper thread and bobbin thread should also be suitable for the fabric and needle being used.
Check the Needle Plate and Bobbin Case
A needle strike can leave a small rough mark or burr on the needle plate, bobbin case or hook area.
These rough areas may catch the thread and contribute to shredding, breaking or tangling.
With the machine switched off, inspect the accessible areas carefully. Do not dismantle parts that the manual does not instruct you to remove.
If you notice a damaged bobbin case, deep needle mark or sharp edge, stop using the machine and arrange an appropriate repair or replacement.
What to Do When the Fabric Is Trapped
Do not pull the fabric backwards or sideways.
Pulling forcefully can bend the needle, tear the fabric or damage the bobbin mechanism.
- Stop sewing.
- Switch off the machine.
- Raise the needle using the handwheel if possible.
- Raise the presser foot.
- Cut the upper thread near the spool.
- Cut accessible tangled threads beneath the fabric.
- Remove the needle plate only if your manual permits it.
- Lift the fabric away gently once the threads are released.
After removing the fabric, clear every loose thread from the bobbin area before reassembling and testing the machine.
How to Prevent Bird Nesting Before You Sew
Before beginning each seam:
- Thread the machine with the presser foot raised.
- Check that the upper thread passes through the take-up lever.
- Make sure the bobbin is wound and inserted correctly.
- Use the correct needle for the fabric.
- Place both thread tails behind the presser foot.
- Lower the presser foot.
- Begin sewing slowly.
- Test the stitching on a fabric scrap when necessary.
These simple checks can prevent most cases of bird nesting and save a great deal of time with the seam ripper.
Quick Troubleshooting Checklist
When thread is bunching underneath the fabric, check:
- ☐ The presser foot was raised during threading.
- ☐ The take-up lever has been threaded.
- ☐ The upper thread follows every guide.
- ☐ The spool is not catching.
- ☐ The bobbin is wound evenly.
- ☐ The bobbin is the correct type.
- ☐ The bobbin is inserted in the correct direction.
- ☐ The needle is straight and suitable.
- ☐ Both thread tails are behind the presser foot.
- ☐ The presser foot is lowered before sewing.
- ☐ The stitching has been tested on a scrap.
When Bird Nesting Happens at the Beginning of the Seam
If the tangle appears immediately after the first stitch, check the thread tails and presser foot first.
Make sure:
- Both thread tails are beneath and behind the presser foot.
- The tails are held gently for the first few stitches.
- The presser foot has been lowered.
- The fabric begins far enough beneath the foot to be supported.
- The seam is started slowly.
Very lightweight fabric can sometimes be pushed into the needle-plate opening at the beginning of a seam. Starting a few millimetres from the edge, using a straight-stitch plate where appropriate or beginning on a small fabric leader may help.
When Bird Nesting Starts Halfway Through a Seam
If the stitching begins correctly and tangles later, look for something that has changed during sewing.
Check whether:
- The upper thread has caught around the spool.
- The spool cap has moved.
- The thread has jumped out of a guide.
- The bobbin is nearly empty or damaged.
- The needle has struck a pin or thick seam.
- Lint or loose thread has collected in the bobbin area.
- The fabric has been pulled rather than guided.
Stop, remove the tangle and recheck the complete threading route before continuing.
When to Have the Sewing Machine Checked
Most bird nesting can be fixed with correct threading and bobbin checks.
Professional attention may be needed if:
- The machine continues tangling after repeated correct rethreading.
- The needle repeatedly strikes the bobbin case or needle plate.
- The handwheel remains difficult to turn after all thread has been removed.
- The bobbin case appears damaged.
- The machine makes grinding or knocking sounds.
- The timing appears incorrect.
- The problem occurs with several needles, threads and fabrics.
Do not force the machine to continue sewing when there is an obvious mechanical problem.
Frequently Asked Questions
Why Is the Thread Tangling Underneath When the Bobbin Looks Fine?
The upper thread may not be sitting inside the tension discs or may have missed the take-up lever. Rethread the machine completely with the presser foot raised.
Does Thread Bunching Mean the Bobbin Tension Is Wrong?
Not necessarily. Bird nesting underneath is often caused by the upper threading. Check the upper thread and bobbin insertion before changing any tension settings.
Why Must the Presser Foot Be Raised During Threading?
Raising the presser foot opens the tension discs on many machines, allowing the upper thread to sit correctly inside the tension system.
Why Must the Presser Foot Be Lowered During Sewing?
Lowering the foot closes the tension system and holds the fabric against the feed dogs. Sewing with it raised can quickly create loose loops underneath.
Can the Wrong Needle Cause Bird Nesting?
Yes. A bent, blunt or unsuitable needle can interfere with stitch formation. Fit a fresh needle that suits the fabric and thread.
Should I Hold the Thread Tails Every Time?
It is a useful habit, particularly at the start of lightweight seams or when your machine tends to pull the loose ends underneath the fabric.
Can Cheap Thread Cause Thread Bunching?
Poor-quality or damaged thread can contribute to inconsistent stitching, snapping and tangling. Try a dependable thread if other checks do not solve the problem.
Why Does the Fabric Get Pulled into the Needle Plate?
The fabric may be very lightweight, the needle may be too large or blunt, or the seam may be starting too close to the raw edge. Test a finer needle and begin slightly further from the edge.
Should I Change the Tension Number?
Only after checking the threading, bobbin, needle and thread. Tension should not be the first adjustment when the machine was previously sewing correctly.
Why Does Bird Nesting Keep Returning?
Repeated tangles may indicate that the thread is catching intermittently, the machine is missing a threading guide, the bobbin is incorrect or damaged, or the bobbin area contains thread or lint.
Fix the Simple Things First
Thread bunching underneath the fabric looks dramatic, but it is often caused by a straightforward threading problem.
Avoid the common sewing mistakes first by removing the tangled thread, clearing the bobbin area and rethreading the machine with the presser foot raised. Then check the bobbin, needle and thread tails before sewing slowly on a scrap.
A calm, methodical check is far more useful than changing several settings at once.