The bobbin provides thread for the underside of the seam. When the tension for the upper and lower thread is set correctly, the stitches on the underside of the seam are evenly spaced and nearly invisible from the top of the seam.

Bobbins come in different shapes and sizes and vary by sewing machine.  Some machines use plastic bobbins and others use metal. Some bobbins have a domed top, while others are flat. Serger overlock machines don’t use bobbins at all.

• The Sailrite^® Fabricator^® uses high-capacity “Class M” metal bobbins.
• The SINGER Heavy-Duty 6380 sewing machine uses “Class 15” clear plastic bobbins.

Always use the correct bobbin for your machine, otherwise, you’ll have a big loopy mess of tangled thread on your hands. When in doubt, check your sewing machine manual.

It’s frustrating to run out of bobbin thread in the middle of a seam! To minimize downtime, always have a supply a pre-wound bobbins on hand. Most home sewing machines have a built-in bobbin winder.  Better yet, if you have a separate bobbin-winding machine, you won’t have to unthread your sewing machine every time you need to wind a bobbin.