Also...other things that can cause the needle to flex (bend) resulting in skipped stitches and broken needles...
Make sure the quilt sandwich is not too tight on the frame. You should be able to push up from the underside with the tips of your fingers & just be able to grab them with your other hand.
Make sure the takeup bar (bar that goes through the bed of the machine) is not too high...you should be able to just fit the very tips of your fingers between the bar and the bed of the machine.
Make sure the needle is not in backwards or crooked. Also make sure it's up in the shaft all the way.
Hope this helps.
Marge is so right about the sandwich tension. I used a Juki on the frame until I got a larger frame. Two things would cause the needle to break: stretching the quilt sandwich too tight and going too fast. If your tension disks seem tight: unthread your machine..always raise presser foot when doing so....take 2 or 3 strands of poly thread or cotton that is not linty and "floss" your tension disks. If you have a little lint ball in there it should take it out. Watch the tension video and don't be afraid to change your bobbin tension. Good luck.
Changed to a 16 wt. jean needle. Seems to have stopped shredding thread.
Thank you all for sharing your knowledge with me.