Well, it’s the term used to describe the tangled mess of threads that happens sometimes on the underside of your fabric when machine sewing. What causes it? There are a number of possible reasons.
The first that comes to my mind is the top thread might be incorrectly threaded in the machine. Remove the thread by clipping it near the spool and pulling it out at the needle or needle area. Don’t grab it at the top and whizz it out backwards! This does NOT make your machine happy! Rethread the top, making sure to follow the steps correctly. (Refer to your machine manual if you need to. Most machines now days also show a threading diagram on the machine.) Go ahead and make sure the bobbin is correctly inserted, too. Test a line of stitching on a scrap of fabric before returning to your project.
If that doesn’t solve the issue, check your bobbin case for lint. This can really build up, depending on what type of fabric you’re sewing. Remove the bobbin and I bet you’ll see some lint, dust, maybe even specks of thread, in the bobbin case. Your machine may have come with a tiny lint brush. Use that to gently grab any lint and dust you can see in the bobbin case and around it. I do not recommend using canned air. This just blows the dust and lint somewhere else, which you’ll have to clean anyway. But more importantly, it can blow the dust up into the machine where you can’t get to it.
In the same way that different fabrics create different amounts of lint, threads do, too. Use a good quality thread. They do have less fuzz and are cleaner and nicer to your machine. Threads that are more tightly spun will glide more smoothly through your machine, giving you more consistent stitches, and stitch strength. How to tell the difference? Sometimes just by feel – it will be obvious. But hold your thread up to a light. If you see a lot of straggly burrs, fuzzy looking, it’s not going to give you the best results. Finer, better quality thread, will be stronger and have much less fuzziness.
Back to the bird nests. Something I was taught back many years ago, before the age of computerized machines, was to gently hold your top and bobbin threads as you begin a line of stitching. This will prevent them being “sucked” into the bobbin area and tangling as you start your seam. Just hold them slightly taut behind your fabric for a few stitches at the beginning.
Another reason for bird nesting can be thread tension. I don’t recommend changing the bobbin tension, which is a tiny adjustment screw on the bobbin case. But the top tension can be adjusted, if needed.
Follow these and other easy steps to make your sewing experience enjoyable and rewarding. Happy sewing!