Originally Posted by Illsa
Sometimes I can ignore the thread balls and continue sewing and the stitches are perfect for a long time like one row of 86" quilt before it shreds the thread or breaks the thread. Completely baffles and frustrates me when it can work perfect then screw up. Machines aren't supposed to do that I didn't think.
If the cotton is shredding as well, it indicates that the needle hole is too small for the weight of cotton that you are using. Try a top stitch or metalic thread needle (they are the same needle in any case), as they have a longer hole and a groove at the back to house the thread as it goes into the fabric. Number 12 weight cotton is the thickest that you can use if going through a sewing machine needle.