Here in this article, you will learn Principles of Lock and Chain Stitch Formation and Its Differences with phase wise details. The Principles of Lock Stitch Formation Lock stitch m/c requires two groups of threads to form a stitch.A needle thread that feeds from the top & a lower thread from a bobbin.A rotary hook catches the needle thread loop as it passes around … [Read more...] about Principles of Lock and Chain Stitch Formation and Its Differences