Perfect stitching is easy to achieve if you thread the machine properly and make the right adjustments in the stitch length, tension, and pressure. These adjustments depend on your fabric and the kind of stitch desired. Consult your machine manual for threading procedures and location of controls.
The stitch length regulator is on either an inch scale from 0 to 20, a metric scale from 0 to 4, or a numerical scale from 0 to 9. For normal stitching, set the regulator at 10 to 12 stitches per inch, or at the number 3 for metric scale machines. On the numerical scale, higher numbers form a larger stitch; if a shorter stitch is desired, dial a lower number. An average stitch length is at number 5.
Bobbins may be built-in or removable for winding. Bobbins with a built-in case are wound in the case. Removable bobbins have a removable bobbin case with a tension adjustment screw. They may be wound on the top or side of the machine. Start with an empty bobbin so the thread will wind evenly. Do not wind it too full or the bobbin thread will break.
In the ideal stitch, both top and bobbin thread are drawn equally into the fabric, and the link is formed midway between fabric layers. The stitch tension control determines the amount of tension on the threads as they pass through the machine. Too much tension results in too little thread fed into the stitch. This causes the fabric to pucker. Too little tension produces too much thread and a weak, loose stitch.
Adjust the pressure regulator for light pressure on heavyweight fabrics, more pressure on light fabrics. Correct pressure ensures even feeding of the fabric layers during stitching. Some machines automatically adjust tension and pressure to the fabric.
Always check tension and pressure on a scrap of fabric before starting to sew. When experimenting with pressure and tension, thread the machine with different colors for top and bobbin thread to make the stitch links easier to see.