Broken threads while quilting and sewing are typically caused by one of these issues:
Thread delivery: Sometimes, the top thread will come out of the take-up lever or thread guides, which causes the thread to break or skipped stitches. Rethread your top thread, ensuring it goes through the appropriate thread guides and take-up lever.
Bad/wrong needle: Replace the current needle with a new one, sized appropriately for your thread weight. A 40 wt. thread works well with a #90/14 needle, while a 50 wt. thread with a #80/12 needle.
Tension problems: If your top tension is too tight, the thread can easily break. Start with your machine's default tension (typically 5.0 for home machines) and don't be afraid to reduceit. You can always revert to the default setting. Remember that decorative threads generally need looser tension.
Thread quality: Low-quality threads, such as short staple cotton or spun polyester, produce excessive lint, which causes friction and can lead to shredding. Use quality threads; your machine will thank you
Speed: Slow down! If the needle is correct, the thread path is clear, the tension is balanced, and you're still experiencing broken threads, slow down your stitch per minute. This is especially relevant for embroidery machines and longarm machines.
Read our educational article on Tips for Balanced Tension