How to Repair a Sewing Machine: Thread Bunches Under Fabric

When customers bring their sewing machine in for repair at my shop, a frequent complaint I hear is the thread bunches under the fabric. This usually then leads to a jam of some sorts and the customer fiddling with the tensions and oiling everything in sight. The finished result is a machine that is jammed, tensions out of whack and a slippery machine.


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Thread bunching can be a symptom of a few ills your sewing machine may have. Some ills are easily rectified and some others I would recommend you take the machine to your nearest sewing repair shop.

Usually, thread bunching under the fabric is a symptom of something wrong above the fabric. There is an inverse relationship between fabric and thread (top of fabric is bottom thread, bottom of fabric is top thread). Most people think thread bunching on the bottom is the bobbin/bottom thread. This is incorrect. We must look for problems starting at the needle and upwards.

Follow the checklist and instruction below to repair the thread bunching issue. If by the end of the steps the problem is not fixed you should bring it to a sewing repair shop.

THREAD MACHINE – This first and easiest thing to do is to re-thread the entire machine. Pay special attention to the take-up lever and the tension assembly.

Always have the presser foot in the UP position when threading the machine. This opens the tension disc to allow the thread to nestle inside the assembly.

Make sure the thread passes through the take up lever

Make sure you inserted the thread in every thread guide

NEEDLE – I always recommend a sharp needle. You may not notice any slight bends, burrs or dullness in the needle which would throw off the timing and the stitch quality.

SPOOL CAP – If you have a horizontal spool pin a spool cap is very important. Its also very important the spool cap covers the end of the spool of thread but make sure its not too big or it will throw off the thread tension.

TOP TENSION DIAL – The setting should be between 3 and 5 on most machines.

Make sure thread is in-between the tension discs. On some machines you can visually see the discs. On newer machines it is hidden.

The best way to know if you threaded the tension assembly correctly is to put the presser foot in the DOWN position. Now take the thread from the right of the tension assembly and pull. Is there tension on the thread or does it pull out very easily? If it pulls out easily you threaded it incorrectly. Try it again — see step one.

FEED DOGS – Be sure the feed dogs are moving and feeding the fabric evenly. Turn the hand-wheel towards you a few times. Can you see the feed dogs moving up and down? Feed dogs are located on the needle plate.

If the feed dogs are not moving

Some machines have a lever to engage and disengage the feed dogs; make sure they are engaged.

If they still are not moving then you may a broken gear.

Now you can test your sewing machine. Set the machine to the widest zig-zag and the longest stitch length. Put a test cloth (one fold in the fabric) under the presser foot and give a go for about 20 or 30 stitches. Did it jam? Is there bunching? I hope not!

Now check the stitch quality. Look at the stitches on the test cloth. Is the thread knot visible on either side of the fabric? The knot should be invisible. This means the knot is nestled between the layers of the fabric and you cannot see it. This is a good indicator of a good stitch.

If you can see the knot, then your tensions are out of balance and they need to be adjusted. All sewing machines have a top tension and a bottom tension. Both tensions must be in balance to have a good stitch quality. It takes quite a bit of experience to balance tensions correctly. I do not recommend doing it yourself.

If you have any questions please feel free to leave me a comment.

You can visit me at www.WayneSight.com for more information on repairing sewing machines.

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