When I have problems using a particular thread, how can I tell if the problem is with the thread, needle, or machine?
Because there are many factors involved in sewing the perfect stitch, it is not always simple to find the cause when things don't go right. Here is a good place to start. Put the thread on a different machine. If you have another machine, try the thread on that one and see if it works. If you don't have another machine, try it on a friend's machine. If the thread runs fine on the other machine, then we know that the problem is with the first machine and not with the thread.
First, check the needle. Make sure the needle is in good condition and is the right size. Remember, most medium (40 wt.), sensitive, and decorative threads require a Topstitch #90/14 needle. Needles wear out as they're used and they are quite inexpensive to replace. Usually you will have skipped stitches and/or thread shredding with bad needles. We recommend using a Topstitch needle for all sewing, quilting, and embroidery work. The only time we don't use a topstitch needle is when we're sewing on knits (use a ballpoint needle) or when sewing on thick, tough fabric such as leather (use a leather needle).
The second place to check is the upper tension setting and tension area. When running decorative threads, the tension needs to be loosened. On a scale of 0 to 10 (with zero being no tension), loosen the tension all the way down between 1 and 2. If that is too loose, resulting in looping on the underside, ease back up slowly until you get the perfect stitch. Make sure the tension disk area is free of lint.
If you are running a metallic or a flat hologram thread, a smooth bobbin thread will work better than a linty bobbin thread. Smooth, mulfi-fliament polyester threads are smooth and have no lint. Bottom Line is an example of a lint-free polyester.
If a cotton or spun poly thread works well but a smooth filament polyester thread is breaking, the problem might be a burr. Smooth filament threads are more susceptible to needle burrs, lint buildup, snags, and rough spots in the thread path than spun threads such as cotton and spun poly.
Here's why: Have you ever had a rough fingernail that easily snagged nylons or other fabrics? It snags smooth fabrics such as nylon much easier than it snags on a cotton t-shirt. If a burr or a rough spot or a cluttered tension disk along the thread path snags a spun thread (cotton or spun poly), it will grab a piece of the thread and pull it out, creating a piece of lint, and the thread keeps on going, barely noticing that it lost a small piece of lint. However, on a smooth non-spun thread such as a filament poly, when a burr or rough spot or a cluttered tension disk snags a piece of the thread, there isn't a piece of lint to give and as a result, it may fray or break.