Bobbin Thread Is Bunching Up – Causes and Solutions

Bunching up of bobbin thread can happen as you sew your garments. A loopy tangled thread can form on the top side of your garment.

It is an annoying sewing machine problem that can affect your project. That’s because you will keep pausing your sewing task to solve the problem.

But, the good news here is, this problem is fixable. This article will explain the reasons bobbin thread bunches up. After which it will highlight some of the solutions to this problem.

Why and How to Fix Bobbin Thread Bunching Up?

Whether a professional or a beginner, anyone can experience thread jam due to bobbin thread bunching up. It can also be the most dreaded problem faced by any seamstress.

Bunching up of bobbin thread stops the sewing machine from moving. Even more, sometimes your machine will start making a sound.

That’s why it is vital to understand the causes. This section seeks to explain why bobbin thread bunches up while sewing, along with some easy solutions.

1. Bobbin Thread Tension

Tension is the force that ensures that the top and bottom stitches are even and remain tight. When the bobbin thread tension is loose, it will bunch up for sure.

The looser the bobbin thread, the higher the chances of thread building up on the top side of the fabric.

That’s because the bobbin easily unwinds, thereby forming loose stitches and leaving excess thread. The loose stitches and the excess thread end up tangling and form messed-up thread bundles.

Solution – Set Bobbin Thread to Appropriate Tension

If you assume the thread tension to be the cause, you can solve it by adjusting it. Adjust the bobbin thread tension by moving the screw on the side of the bobbin clockwise.

Do it gradually until you reach the correct tension. But, do not tamper with the bobbin tension too much. Otherwise, it attracts more problems.

2. Dirt (Debris) Stuck in the Bobbin

Dirt (debris) can clog the sewing machine bobbin. The debris is a result of small cotton or thread pieces. Such tiny particles store up in the bobbin over time. So, if you left them for too long, it can cause problems.

Dirt, on the other hand, expands as time passes. Thus, if you leave the sewing machine without cleaning for a long time, this will make the bobbin thread not move smoothly. It will cause the thread to drag and, in the end, cause the thread to bunch up.

Solution – Clean the Bobbin to Remove Debris

Make it an all-time habit to always clean your bobbin. It will help stop dirt from collecting into it. Besides, it will also remove any thread or cotton pieces that get in it while sewing.

If you are not clear on cleaning your bobbin, read the sewing machine manual or ask someone expert in this field. The manual is the best guide because it has tailor-made guidelines for your sewing machine.

3. Loose Bobbin Screw

Sometimes thread bunching can be a result of a loose bobbin screw. You can notice the bobbin screw on the side of the bobbin. It is also the one to utilize if you want to adjust the bobbin thread tension.

A loose bobbin screw will roll the thread as you sew. Thus, it will result in the thread bunching up.

Solution – Check and Adjust Bobbin Screw Before Sewing

It is an admirable habit to check the sewing machine bobbin before starting your project. That’s because it will help you detect if the bobbin screw is loose. If loose, re-adjust and tug the screw to a desirable position.

4. Bobbin Thread Not Wound Properly

A mistake in threading the bobbin can result in difficulties. So, chances are you didn’t correctly wind the thread on the bobbin. It can even form knots as you wind it. In the end, it will cause the thread to tangle.

Even more, if the bobbin thread is not tight after winding it on the bobbin, it means threading has gone wrong.

Solution – Ensure Correct Threading of Your Bobbin

The bobbin thread should not be loose but tight when wound. If the thread is loose, it is best to unwind it and rethread it.

If you notice a knot in the bobbin thread, you should also unwind it and redo the whole process. Getting rid of the knot will stop the thread from bunching up.

5. Size of the Bobbin

Bobbins come in different sizes, diameters, and heights. If the bobbin size does not match the sewing machine, it will cause the thread to bunch up, for example, a taller bobbin.

Solution – Match the Bobbin Size With the Sewing Machine

If you are looking to use a bobbin that did not come with the machine, make sure you pay attention to the details.

Check its length, depth, and weight to see if they match with the sewing machine’s original bobbin. If these parameters match, then you can go ahead and insert it into the machine.

6. Broken Needles Can Cause Thread Bunch Up

Using the wrong needle on the sewing machine has its negative impact. Bobbin thread bunching up is part of these impacts.

The wrong needle may miss or slip the bobbin thread to form proper stitches as you sew. In the end, it will lead to threading tangling.

The same can happen if the needle you are using on the sewing machine is curved or bent. One of the reasons needles bend is using it on thick fabric.

Solution – Use Quality Needles Only

Use needles that are not bent or broken. Newer and good quality needles catch the bobbin thread well. It will ensure clean, tangle-free stitches. Below are the best needles to choose from, according to your fabric type.

  • Light Fabric (Silk) – 70/10 Needle
  • Average Weight Fabric (Cotton) – 80/11 Needle
  • All Heavy Fabrics – 90/14 Needle

7. Wrong Placement of the Bobbin Case

We usually move the bobbin around a lot. That’s because it has to be threaded every time it runs out of thread.

So, it gives a chance to the possibility of improper replacement in its case. If you don’t fix it in its proper position, you will encounter thread bunching up problems.

Solution – Ensure the Bobbin Is in the Right Position

Inspection of the bobbin position must happen before starting to sew. It will help check if the bobbin is in its correct position and stop the thread from bunching.

8. Thread Weight Difference Between Bobbin and Top Thread

Thread weight is an integral part of sewing. It has to match the fabric type all the time. What’s more, the top thread and bobbin thread weight should also match.

If the threads do not match, the sewing machine will pull them at different rates. As a result, it will cause bunching.

Solution – Use Similar Thread Weight

The bobbin thread weight should always match the top thread weight. It will ensure that the machine pulls the threads at the same rate. When you do it, the bobbin thread bunching problem will stop.

9. Thread Moving Out of the Bobbin Case

In other instances, the bobbin thread can come out of its compartment. So, it will cause excess bobbin thread to unwind. The excess thread is what will create bird nests on the fabric.

Solution – Put the Thread Back in Its Compartment

If the bobbin thread comes out of its compartment as you sew, stop and place it again. It will help stop the thread from building up.

10. Threading With Presser Foot Down

Threading your bobbin while the presser foot is down will cause tension to engage. The result is the thread failing to sit. It will then cause bunching because the needle misses the thread.

Solution – Thread With the Presser Foot Up

All threading should happen while the presser foot is up to allow the thread to sit correctly. Besides, it will ensure the needle has no problems catching the bobbin thread.

That’s it! After understanding the reasons behind bobbin thread bunching up, you can fix this issue with ease.

Are All Sewing Machine Bobbins Universal?

Sewing machines come with bobbins as part of the package. They are one of the removable parts of a sewing machine. Bobbins may not last forever. They can either get lost or damaged over time. But, even though they look the same, they are not alike.

They can range in height, depth, diameter, and even material. So, it means that bobbins can fit in the same brand of sewing machines without applying a lot of effort but may not fit in others.

Does Bunched Up Bobbin Thread Result in Loose Stitches?

Once in a while, the sewing machine can form loose stitches. The common cause of loose stitches is the bobbin. But, there are other causes, such as improper threading and wrong needle and thread size combination.

To solve this problem, understand the causes first. If it is due to wrong threading, then rethreading is the perfect solution. Another solution is to change the needle and thread combination.



I'm Jessica Flores, a professional fashion designer and an expert seamstress. Crafting has always been a deep-seated passion of mine, one that has flourished and evolved over the years. I've dedicated considerable time to both studying and practicing in the realm of fashion and sewing, amassing a wealth of experience and skills. It brings me great joy to share these insights and experiences with you all, hoping to inspire and foster a similar passion for the art of sewing.

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