Follow the diagram printed on your machine or in your instruction manual, as different machine models may have slight differences. In general, the sequence is:
- Place the spool of thread on the spool pin at the top of the machine.
- Raise the presser foot to release tension.
- Cut the thread end, so it is smooth, with no frayed edges.
- Guide the thread through the hooks and loops that lead to the tension discs.
- Be sure thread passes between the tension discs.
- Thread the end through the take-up lever (arm that moves up and down just above the needle.
- Follow guides until you thread the needle from front to back. Be sure thread is not wrapped around needle or presser foot.
Check your manual for correct bobbin winding and threading. Whether you have a drop-in bobbin (top loading) or a front loading bobbin, be sure you insert the bobbin with the thread placed so that when you pull the end, the bobbin rotates clockwise. Be sure the thread end passes through the tension slot.
On a scrap of fabric, hold both thread ends at the back of the machine. Put presser foot down. Slowly stitch, letting go of thread ends after a few stitches. Remove test fabric and check the stitching.
If stitches look even and the top and bottom threads seem to meet between the layers (no thread lying on top of the fabric), then you are ready to sew. If top or bottom thread is too loose or tight, follow manual instructions for adjusting the top or bobbin tension and test again.
If thread is breaking, you may have tension too tight, or you may have missed a step while threading. Check your thread path to be sure you passed the thread through every guide in the correct order. You might also have a problem with rough spots on the spool where the thread unwinds—a spool cap can fix this problem.
Another common cause of poor stitching is a mismatch between needle and thread or fabric. Use smaller needles with lightweight fabric and thread, larger with heavy thread and fabric. Also, be sure to use a sharp needle with tightly woven fabrics and a universal or stretch needle with knits.
Finally, you can expect stitching problems with poor quality thread. If you are using a new needle, quality thread, and correct threading path, with tension properly adjusted, you should see uniform stitch quality.
If troubleshooting fails to give you good results, consult a Singer service shop.