Bobbin problem
 

I just started sewing some nine patches to a plain square. I sew 2-4 squares then my top thread wraps around my bobbin thread a couple times then jams. I'm using white thread in the top and a colored thread in the bobbin, so I know it's the top thread. I've re-threaded several times, cleaned bobbin area a lot and changed my needle. Any ideas.

What machine? Clean the tension disks if you can access them. Is the needle threaded in the right direction. I have three machines in my family room. One threads from the left, one from the right and one from center. They will not sew if the needle is not threaded the correct direction.

It's the Juki 600. The top thread loops around the bobbin, knots then breaks. I know the needle is in right as the needle threader works, it wouldn't if the needle was in wrong. Later I'll have DH take the case off to see if anything is amiss.

You mentioned three machines. Do you have the correct bobbin in the machine? Is the bobbin wound tight?

Try a different bobbin.

Is the thread catching on the spool stand? Watch as the top thread un-winds that it is smooth.

You have done most all the troubleshooting that correct sewing issues. Good luck!

I agree with Rhonda K, I had similar problems and it took me a long time (I'm not the brightest lamp in the room) to try a different bobbin. The next bobbin worked fine. Took a good look at the other bobbin and realized that the threads were loose. What??? Don't know how that happened but the tight thread bobbin worked just fine.

also be sure your machine doesn't need cleaning.

You say your thread is two different colors. Are they also different weights? That can for sure make problems.

They are the same brand & weight. Wanted to use up the last little bit of the yellow cone so filled up a few bobbins.

Might be fixed
 

Held my breath and tightened the tension screw on the bobbin casing ( a tad). Sewed a whole strip no breakage. Sure hope this is the answer, I'm so not into messing with bobbin tension.

Take the bobbin out and see if it has thread dangling from it. Cut that off if it does.

Also, check to see if your plastic bobbin is rough around the edges. Throw it away if it is, and use another bobbin.

The plastic bobbin basket can become damaged. Pull it out and see if it has burrs or punctures. Gently polish them down with a very fine sandpaper (about 400 to 500 grit).