Why Does My Thread Keep Breaking?
Why is my sewing machine thread breaking while sewing? Let's dive into the chief causes and solutions
“My thread keeps breaking in my sewing machine.”
This is one of the most common issues we see at The Sewing Machine Shop. In this edition of The Sewing Machine Newsletter, I’ll walk you through the exact troubleshooting process I use, step by step, when a machine is breaking thread.
Rethread the sewing machine with quality thread and insert a new needle that is size 80/12 or 90/14.
Make sure I am using a spool cap that is slightly larger than the end of the plastic end of the thread spool.
Perform the pull test to locate potential thread snag in the upper half of the machine.
Inspect the needle plate, bobbin case, and presser foot for burrs.
Inspect the machine for adhesive on the bobbin case and/or hook; clean off adhesive if need be.
Step 1: Rethread and Replace the Needle
First, I rethread the machine with quality thread and insert a new needle (preferably size 80/12, or 90/14).
Old or cheap thread is brittle and often the sole cause of breakage. You can spend $150–200 on a service, or spend $3.30 on a spool of Mettler and fix it yourself. I’ve seen it happen many times.
Next, I install a fresh needle. The size of the needle corresponds with the size of the eye —— the eye of a size 70/10 needle is smaller than the eye of a size 80/12 needle, which is smaller than a 90/14, which is smaller than a 100/16, and so on.
A small eye (e.g. size 70/10 or 65/9 needle) may be too small for the thread to pass through smoothly, therefore increasing friction, which can shred the thread. I want to eliminate a small needle eye as possibility for thread breakage, which is why my first step of troubleshooting is to insert a fresh needle with a sizable eye (80/12 or 90/14).
Again, a full service on a machine costs $150-200. A fresh needle is less than a buck.
Step 2: Check the Spool Cap
When rethreading, take a close look at your spool cap.
The end of your thread spool is made of rough plastic with tiny imperfections. The spool cap, by contrast, is smooth. If your cap is too small, the thread rides over the rough edge of the spool instead of the smooth plastic of the cap. That can cause snagging and breakage.
Rule of thumb:
The spool cap should be slightly larger than the end of the spool —— not smaller, and not way bigger. Too small and the thread will snag. Too large and the cap itself can interfere with thread flow.
Many machines come into our shop with this exact issue. Fixing it takes two seconds and saves a lot of headaches.
Step 3: Perform the Pull Test
If the thread is still breaking, I perform The Pull Test.
Longtime readers of this newsletter may recall The Pull Test as a cure for thread loops on the underside of the fabric —— so why would I perform The Pull Test for thread breaking? Because I want to check for thread snags.
Thread your machine fully, except for the needle, and lift the presser foot. Gently pull the thread. It should move freely, with almost no resistance. However, if the upper thread was snagging on something, then I should be able to feel that snag while performing The Pull Test.
If you feel a snag or drag, that means the upper thread is catching somewhere. Slowly unthread the machine while repeating the Pull Test to pinpoint the location of the snag by process of elimination.
Continue performing The Pull Test as you slowly unthread the machine. Do you feel a snag now that the needle thread guide is no longer threaded? If the answer is yes, then continue to gradually unthread the machine while performing The Pull Test. If the answer is no, then the snag is located in the needle thread guide and you need to smooth it out or replace it. The same principle applies for if you happen to locate the snag at the tension discs, the take-up lever, the checkspring, and so on.
Step 4: Inspect for Burrs
If the Pull Test is smooth but the thread still breaks, the problem may be in the lower half of the machine.
Check for burrs or rough spots on the:
Needle plate hole
Presser foot
Bobbin case and bobbin basket
Even a tiny burr can shred thread. Lightly buff it out with emery cord, or replace the part if the damage is severe.
Step 5: Check for Adhesive Buildup
If you use adhesives while sewing (like sticky stabilizers or fusible products or velcro), inspect the bobbin, bobbin case, and hook for residue.
Excess or poor-quality adhesive can gum up the lower mechanism, causing the thread to stick and snap as the machine cycles. Minor buildup can often be cleaned carefully at home; heavier buildup may require a technician to disassemble and clean the machine.
The sewing machine thread is still breaking. . . .
Now what?
If your thread still keeps breaking after these steps, it’s time to bring the machine to a trained technician. Some causes of thread breakage are subtle and maddening, even for professionals. I’ve seen many repairmen throw their tools in frustration after chasing this problem.
Thank you for reading!
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A person who is learning to sew complained about her thread breaking, and the first thing I said was 'change the needle!" Apparently, it had never come up that needles can only be used for so long. Your article (that just came and was appreciated) led me to the one on non-stick needles.. I have a lot of different needles, but not the nonstick ones. I seldom use adhesive, but want to try these. Thank you for all of these tips. I am an old and retired Home Ec teacher, it is good to refresh..
Great advice again. I knew most of these but good to have a reminder and solutions to pass into my students. I’ll be sharing this on my own blog with full accreditation of course. Thank you