rryder

Have you tried starting with fairly small quilt sandwiches, maybe placemat size or even slightly smaller? That way you can eliminate drag as one of the culprits and look at other possibilities like the type of needle, thread tension, etc.

Try using a new topstitch needle in 90/14 size. Worn needles can cause thread to shred.

Also be aware that build up of thread can also cause thread breakage, so if you are trying to quilt a pattern that requires travel stitching along the same path multiple times, that can cause breakage if you are not using a good strong thread.

Check your needle plate for burs, they can also cause thread breakage.

Make sure your bobbin is inserted into the bobbin case properly. Check your manual to see if the thread from your bobbin should hang down from the left or the right side as you insert it into the bobbin case. An incorrectly threaded bobbin case can cause top thread breakage

Next, using a small practice sandwich try the following:

With your presser foot up, loosen your top tension slightly.

Thread your machine, making sure your presser foot is up so the thread goes into the tension discs correctly. Thread your needle. If you lowered your presser foot when you threaded your needle, raise it and pull the end of your thread toward the back of the machine, it should feel smooth and have little to no resistance. If you feel resistance or it doesn't pull smoothly, rethread.

Using a small practice sandwich try the following:


Relax your upper body and try to move your hands smoothly. Start out moving in a line or a gentle curve to see how that feels. Don't try changing direction, just go in straight lines, or gentle curves at first. Try to speed up your machine without speeding up your hands. If your machine has a slider bar to control the speed do not set it too slow, better to start out with the machine a little too fast for your hand movement than the other way around. Try some straight lines and gentle curves moving from front to back, then try some from left to right, etc. Next, try doing some large circles. If you are having success with those movements and no thread breakage, it's time to try doing changes of direction. Start out with something easy like a series of undulating horizontal or vertical lines. Once you're able to do those it's time to work on an easy all over pattern like stipples.

Hope all that helps.
Rob