The American system of watch manufacturing is a set of manufacturing techniques and best-practices to be used in the manufacture of watches and timepieces. It is derived from the American system of manufacturing techniques (also called "armory practices"), a set of general techniques and guidelines for manufacturing that was developed in the 19th century. The system calls for using interchangeable parts, which is made possible by a strict system of organization, the extensive use of the machine shop, and quality control systems utilizing gauges to ensure precise and uniform dimensions. It was developed by Aaron Lufkin Dennison, a watch repairman who was inspired by the manufacturing techniques of the United States Armory at Springfield, Massachusetts, which manufactured identical parts, al