Before starting up the machine, let’s look at how sewing machines work:
“All sewing machines function on the same basic system. In short, an arm that holds a needle with one thread is positioned over a base plate that holds a bobbin with another thread. When you sew, you insert your fabric between the needle portion and the bobbin portion of the machine. Every time the needle moves up and down through the fabric, the thread from the needle above the fabric is caught by the thread from the bobbin beneath the fabric, creating a lock stitch that secures the layers of fabric together.”
(“Meet Your Sewing Machine” by Mikaela Holmes in the Instructables’ Machine Sewing Class licensed CC-BY-SA)
Watch this quick video to see what this looks like: