Why Does my Sewing Machine Clump the Bobbin Thread?
 

I can be sewing along and then hear this "clunking" noise to find a large clump of thread is left on the underside of my fabric from the bobbin.:( What can be causing this, I have re-inserted the bobbin many times.

Tension would be the first thing I would check, both bobbin and top. After that I would make sure the timing is good, if you're hitting the bobbin case with your needle instead of going through the hole in the case you may need to have it looked at.

Are you sure it's a bobbin problem and not that the thread has come out of the uptake lever?? That's what it usually is with my machine. There's a glop of thread on the underside of the fabric, and the thread has jumped out of the lever.

Make sure the bobbin thread goes into the little slit in the bobbin case too. Sometimes I mess up . Check your manual, which way the thread goes in from the bobbin into the case. Good luck.

What machine do you have? I am wondering if the thread spool is catching the thread every once in awhile. It sounds like a thread path problem to me -- most likely upper thread, but could be lint in the bobbin area or possibly an irregularly-wound bobbin.

I had that happen when I was embroidering. I discovered that if I clean it every time I change the bobbin it runs much smoother.

is it just at the beginning of your sewing line? if so, i'd say it's that you are not holding/securing the top and bobbin threads before the first stitch.

I was thinking tension as well initially but QuiltnNan has a good point also. You may also want to check that there's not a bunch of lint, tiny piece of thread, tip of a broken needle UNDER your bobbin case. You'd be amazed at what havoc those things can create!

I'm having the same problem, pseudoquilter. I sew about 2 feet on a straight seam, then hear the "clunk" and see a lot of threads in the bobbin area. I cleaned all the gunk around the bobbin area and rewound another bobbin. What I have done since has been working. Hopefully, it keeps on working or I think I will be looking for a new machine. Mine is pretty old. Maybe it's just a Michigan problem. LOL

Cybermom2, I think it is a Michigan problem because my machine just started doing this about a week ago!