Bobbin thread breaking despite careful adjustment.

May 13, 2007 7:47 AM

Thread breaking on sewing machine; all common fixes ineffective.

I have an almost-brand new Kenmore sewing machine I am using to piece a quilt top. I am having persistent problems with the bobbin thread breaking, and haven't been able to solve it with any of the usual fixes. For instance:

The bobbin is wound correctly and inserted correctly.

The top and bottom thread are the same weight--from the same spool.

The needle is the right kind for the weight of thread I'm using.

The needle is not bent or dulled; this happens even with a brand-new needle.

Adjusting tension doesn't fix the problem. For instance, right now I have the tension adjusted properly as far as I can tell--by which I mean that if I loosen the bobbin thread at all, I get thread lying on top of the fabric (for the 1/2 inch it will sew before breaking) and if I tighten it at all, I get thread lying on the bottom.

When I hold the bobbin case in my hand and try to pull the thread out, the bobbin stops turning every half turn. If I then tap the bobbin, it will turn another half-turn before snagging again. If the bobbin is in the machine and I try to pull the bobbin thread by hand, I can't.

I can't figure out the fix for this. My sewing machine's manual and websites I've found just tell me to do the things I've already done. Troubleshooting tips would be very welcome.

posted by not that girl to sports, hobbies, & recreation (12 comments total)

Have you tried using different thread? Does it break equally with different types of thread and different brands?

Sometimes, you just have poor quality thread.
posted by Margalo Epps at 7:56 AM on May 13, 2007

Sounds like the bobbin may have a fault. Is the machine still under warranty? Have you tried other bobbins?

A sewing machine repair professional should be able to diagnose and fix a problem like this for miniumum fuss.
posted by tomble at 8:30 AM on May 13, 2007

I agree, something wrong with your bobbin/case. You should be able to pull the thread out evenly.
posted by oneirodynia at 9:03 AM on May 13, 2007

Yeah, it sounds like the bobbin and/or the bobbin case is not quite round, and it gets stuck in a certain position. Try a different bobbin, and if that doesn't work, buy a replacement bobbin case.

Make sure you are using the correct bobbin for your machine. Bobbins all look pretty much the same but the dimensions can be slightly different. If your bobbins came with the brand-new machine, you're OK - if not, you might have the wrong bobbins. Buy a new package of bobbins that are specifically for your make and model of machine before investing in a new bobbin case.

Department stores probably won't have bobbin cases, but a sewing machine dealer might (you should call and ask if they have parts for your exact make and model, since they are often not interchngeable). If all else fails, you can order them online.
posted by Quietgal at 9:12 AM on May 13, 2007

Lightweight aluminum or plastic bobbins are much more susceptible to bending and swelling due to overwinding than are steel bobbins. Aluminum and plastic bobbins have the advantage of being cheaper to manufacture and less likely to overspin in high speed industrial machines, particularly those equipped with automatic thread trimmers. But in home machines, you are generally better off to use steel bobbins, if your machine accepts them. You can tell steel bobbins from aluminum ones definitively with a magnet, but also, steel bobbins will feel a bit heavier, when empty than aluminum ones.

Some bobbin cases, especially in industrial machines, have an anti-backlash washer or spring inside the bobbin case, which can cause excessive bobbin drag if lint gets underneath it. So, examine your bobbin case carefully to see if yours is having that problem. In a home machine, you don't usually need such devices.

Another thing that can cause this kind of problem is that the bobbin winder on the machine is not adjusted properly, or that the rubber tire which provides bobbin winding power to the bobbin winder spindle has worn. In either case, the wind will not be even at the perimeter when the bobbin is filled, leading to uneven bobbin tension, and bobbin thread breakage. The bobbin winder in most home machines has a couple of adjustments to take care of these tendencies, but sometimes the problem is as easily fixed as replacing the rubber "tire" of the winder stem with a new one.

Until you can smoothly pull thread from the bobbin, through the throat plate, yards at a time, you won't be able to sew. First, try different bobbins. If that fixes it, discard the bobbin that was causing problems. If different bobbins all have the same issue when full, try unwinding a few bobbins by hand, to halfway, before you put them in the machine. If that helps, more than likely your bobbin winder is out of adjustment.
posted by paulsc at 9:15 AM on May 13, 2007

Try different thread in a different bobbin. Make sure there is no lint or other sewing matter under the bobbin case. Sometimes you'll find an old thread has worked its way into the case. (I know you said the machine is almost new but if you've successfully completed a project before this one there may be gunk in the machine.)

Also, I have an older Kenmore and if I don't have both the thread tension and the bobbin tension just right the thing will be bitchy about sewing anything.
posted by fluffy battle kitten at 11:22 AM on May 13, 2007

paulsc's answer is great, though I don't think you need steel bobbins... but if you have the (common) plastic bobbins, you might just have one that's a little warped. Just swapping out bobbins might do the trick.

I only have this problem on my Kenmore when I don't wind the bobbins properly, though. (Like last night, I botched up the first part of the wind but then kept going anyway. The bobbin worked fine until it reached the messy part, then SNAP!) If your Kenmore is like mine, you have to pull the bobbin winder thing to the right after you start the wind to make it taut, otherwise there's not enough tension in the wind and sometimes you get bad results, depending on the thread.

I think it's more likely you have a bad bobbin. (If it's plastic, could there be just a tiny nubbin of plastic sticking out that is catching the thread? Something that could be sanded off?)
posted by litlnemo at 3:26 PM on May 13, 2007

I know this sounds stupid, but I once picked up the wrong type of thread by mistake and had this exact same problem. You sound like you know what kind of thread you're using but if it's new, just double-check. There is nothing quite like accidentally getting embroidery thread. The bobbin behaved like what you're describing when that happened to me.
posted by Medieval Maven at 4:06 PM on May 13, 2007

I love that there are people out there who know enough about bobbins to give me these detailed technical answers. I feel heartened simply to have a plan for some things to look into. I do have an ignorant follow-up question, which is: how do I know whether I am getting the bobbin wound properly?
posted by not that girl at 5:38 PM on May 13, 2007

A properly wound bobbin should look neat, with winding in clean, flat layers. Scrambly looking bits are bad. Also, if you wind on too much and/or use too much tension while winding, your bobbin may swell. A properly wound bobbin will have flat, parallel sides.
posted by flabdablet at 7:03 PM on May 13, 2007

On my admittedly ancient straight-only sewing machine, I've found that if the upper thread tension is too high, the bottom thread (from the bobbin) will break. If you can try adjusting your top thread tension, that may be helpful.
posted by Lynsey at 9:51 AM on May 14, 2007

I am popping back in to say that I have finally had a chance to sit down with my machine, and it was the thread. I would never have thought of that, I don't think, which says something about the pathetic-ness of my brain. I could tell as soon as I threaded the bobbin that it was different, and it is sewing like a charm. Thanks to all of you--even though the fix was an easy one, I feel like I know more about my machine now.
posted by not that girl at 10:38 PM on May 29, 2007