The dreaded "bird nesting" syndrome is a common sewing machine problem many of us have experienced at one time or another while sewing, either on the top or underneath the fabric. There are lots of reasons for sewing machine thread bunching up, and luckily, many of the solutions are easy and do not require a trip to your favorite sewing machine mechanic.
Anytime the sewing machine thread is bunching up, or bird nesting, on the top of your fabric, the culprit has something to do with your bobbin. Here are some things to check before calling sewing repair 911:
1. Is your bobbin threaded correctly?
If your machine uses a bobbin case, take the bobbin completely out of the case and re-thread it. Be careful to follow the instructions for your machine, and make sure you have the bobbin thread engaged in the bobbin tension. A good test for this is to hold onto the bobbin thread with one hand. If the bobbin drops all the way to the floor, you missed the tension spring in the bobbin case.
2. Is your bobbin case tension too loose?
If you have loosened the screw on your bobbin case to accommodate thicker threads for surface design work, you might not have re-adjusted it correctly for regular thread. After correctly threading the bobbin case, tug gently on the bobbin thread. You should feel some resistance, but the thread should move freely. If you have not made any changes to this tension setting, it is likely not to be the cause of any thread bunches, as it is set correctly at the factory. If you do adjust it, be sure to do so in small increments to avoid dislodging the entire screw.
Conversely, the reasons that thread can bunch up underneath your fabric have all to do with your needle tension.
1. Is the needle thread threaded correctly?
Cut the thread a few inches from the spool, and pull it through the needle. Re-thread, taking care to engage the upper thread completely in the tension discs. I always suggest to my students that they hold the thread on either side of the tension disc, and slide it back and forth a bit between the plates with a flossing motion. The tension discs need to "grasp" the thread snugly.
2. Is the presser foot up?
Duh. We've all done it!
3. Is your machine clean?
Frequent dusting underneath the throat plate and along the thread path will prevent all sorts of stitching and machine problems. Of course, good quality thread, a new, sharp sewing machine needle, and the correct bobbins for your make and model of sewing machine are basic requirements for producing good quality stitches. Frequent dusting, cleaning and oiling will also prevent these and many other stitching problems you might encounter.