There I was strolling through JoAnn's, when I found an friend from high school sitting at one of the embroidery machines that are sold there. Waving ensued and soon I was by her side. After hugs and hellos, we were soon discussing and scratching our heads over the thread jams she was experiencing. I had been having the same kinds of aggravations a few months back on a project, and I learned a new trick or two. So I thought it might be a good topic to bring up for review for us long-time sewists and a primer for the new sewists.
Thread jams aren't limited to embroidery machines. They are usually associated with flimsy or stretchy fabrics, but not exclusively by any means. Stabilizing your fabics will help eliminate the problems. If you are embroidering, stabilize a thin fabric with 2 or 3 layers of stabilizer, and always add more stabilizer if you tear it while tearing out a thread ball. If you're doing straight stitching, try putting a little stabilizer on the seam then sew.
Check your needle. Is it well-tightened in the shaft. An unsharp needle is many times the culprit. My embroidery teacher always advises to replace your embroidering needle after 10 hours on medium designs. Many instructors recommend changing your needle with each project. I must confess, I don't do this while straight stitching. I've been sewing long enough that I can "hear" when the needle is not moving through the fabric with ease, and I change it immediately. However, I don't recommend this method. Sewing through tightly woven fabrics, polyesters, spandex, and especially metallics puts the needle through more wear and tear than a loosely woven fabric. If your last project involved these fibers, you might want to put a fresh needle in your machine. Thread nests can bend a needle, too, so always make sure your needle is sharp and straight and tight.
A good quality thread is important, too. I use Gutermann. It has long fibers instead of short fibers that many threads have, which gives the thread greater strength and it makes far less lint prolonging the longevity of your machine. When embroidering, use polyester or rayon thread on the top (30 or 40 wt.) and a 40 wt. polyester bobbin thread. Cotton is just not strong enough for the embroidery machine. These guidelines are good ones for straight sewing also. If you're using metallic-thread thread, make sure you have a metallic-thread needle in your machine. The eye and shaft of the metallic needle is designed to reduce the friction on this type of thread. Another tip -- when I use metallic threads, I put them in a cup instead of the dowel to help lessen the tension on the thread and keep it from binding up. Some people swear by using a net, but the cup method works better for me.
Always check your tension, too, and use the recommended values from your machine's manufacturer. All machines differ, but some machines have tension adjustments for the foot as well as the upper and bobbin threads.
The biggest trick I learned was to use a straight-stitch sole plate. This has helped me the most in my straight stitching, but you must remember to ALWAYS change back to the zig-zag plate before changing your stitch. However, if you're working with a flimsy fabric, having a straight-stitch plate will be a great help to you.
Finally brush the lint from your bobbin chase and under the sole plate. Dust and lint particles can cause thread jams. For this reason, I'm really leery of pre-wound bobbins of any kind. The cardboard ones leave disintegrating particles behind, and the plastic ones often have a resin on them that holds them together. I strongly advise to avoid them.
So, to sum up, when you're getting all balled up, check the following:
1. Is your needle tight, straight, sharp?
2. Are your tensions properly set -- top, bobbin, foot?
3. Are you using the proper thread/needle combination?
4. Is your machine clean?
5. Do you need stablilizer?
6. Can you use your straight-stitch sole plate?