In metalworking, a jig is a type of custom-made tool used to control the location and/or motion of another tool. A jig’s primary purpose is to provide repeatability, accuracy, and interchangeability in the manufacturing of products. Unlike a fixture, which only holds the work in a fixed location, jigs both hold the work and guide tools.
There are many types of jigs, and each one is custom-tailored to do a specific job. Many jigs are created because there is a necessity to do so by the tradesmen. Some are made to increase productivity through consistency, to do repetitive activities or to do a job more precisely. Jigs may be well made for frequent use or may be improvised from scrap for a single project, depending on the task.