Originally Posted by Quilting Angel
It actually seems to be shreading. I thought it may be a tension problem, but dropped the tension all the way to 2 and that didn't solve it. It makes a noise, and then I know it's about to break. Looks like it shreds and forms sort of a knot, then breaks.
Shredding is often due to older cotton wrap polyester threads, OR the weight of the thread not matching up with the needle size. For instance I use an 11 or 12 needle to piece and quilt, and the thread weight is 30 or 40 which works well on my machine. That is actually heavier thread than what the needle is rated for, but usually a 14 will handle 60 to 80 weight cotton. Look in your manual to see if the mfgr gives you a table of needle sizes paired up with thread sizes. Make sure you are not using a ball point needle if stitching on wovens. Make sure the machine and bobbin are threaded correctly. Hope this helps.:)