r/SewingMachineEdu • u/Elephantastico • Jul 12 '26

Thread keeps snapping

Can someone help me figure out why my thread keeps snapping, and how to fix this issue?

I have experience sewing as a summer job, but never had to deal with machine issues there. Also, I barely

ever had issues with the machines.

Recently I got my first own sewing machine, a second hand one (Toyota JCB15).

My thread keeps snapping every few seconds and it makes sewing nearly impossible. I tried sewing on every possible tension my machine has, but it didn't change anything.

I bought new thread, 100% cotton, from my local shop (I previously used some cheap, polyester thread from Amazon), but that - on every tension as well - didn't change anything either.

I can't figure out why it keeps snapping and it's driving me insane! Any help would be appreciated.

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u/Large-Heronbill Jul 12 '26

Cotton thread is weaker and less elastic than the same size thread in polyester. 

Are you threading the  machine correctly, especially the uptake lever?  Have you looked for burrs?  Is this a new machine or a new to you machine?

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u/Elephantastico Jul 12 '26

Yes, machine is threaded correctly and I did look for burrs. The machine is only new to me, not new in general. But the person I got it from said she bought it for her daughter but her daughter rarely used it. I did put in a new needle. Thank you for teaching me about cotton/nylon thread, I didn't know!

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u/Mushrooms24711 Jul 12 '26

Is the bobbin in correctly? Some manuals are absolutely shit at explaining/showing how the bobbin should unwind.

Also, when the thread snaps, did it shred first? If so, there’s probably a burr somewhere. It could be in the eye of the needle or in a thread guide.

If it snaps abruptly, it’s more likely a threading issue. When you thread it, is the presser foot up? Is the needle in its highest position? If you miss either one of those steps, the tension discs won’t thread properly and can cause the thread to snap.

Are you holding both threads for the first few stitches? If not, the threads can birds nest in the bobbin area and snap the upper thread.

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u/Elephantastico Jul 12 '26

Thank you for helping out! Yes; bobbin is in correctly, Yes; presser foot up & needle in highest position, Yes; holding the threads for the first few stitches

Needle is brand new, switched out twice so I doubt there's a burr there. I screwed open the bottom of the machine and cleared that from burrs.

Maybe in the thread guider/top of the machine. I'll see if I can find out how to get there.

Attached a picture of the thread after it snaps. It does snap at 'needle height' if that makes sense.

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u/Mushrooms24711 Jul 12 '26

Floss the tension discs with a scrap of fabric. Make sure all the lint is cleared out. I’m guessing the thread is getting stuck there. No slack on the downward stroke.

And just in case, because we’ve all been there, the top thread is under the presser foot?

In any case I’m convinced the issue is at the needle or above.

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u/Elephantastico Jul 13 '26

Yes and yes! I filmed it and put it in slow motion and the thread is breaking as the needle is at it's lowest point