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jig,dance of English origin that is performed also in Ireland and Scotland. It is usually a lively dance, performed by one or more persons, with quick and irregular steps. When the jig was introduced to the United States, it was often danced in minstrel shows. In instrumental music the gigue, the successor to the jig, was used by Bach and Handel in their suites.
in machine building, a type of machine tool attachment used during the machining of holes on a drilling machine. The part being worked is located in or under the jig. Jig guide bushings determine the position of the cutting tool relative to the jig body and, consequently, relative to the part to be machined. The position of the hole axis of each bushing matches the position of the hole axis in the part, and the bushing hole diameter corresponds to the tool diameter. The use of a jig eliminates the marking operation, permits simultaneous machining of two or more holes, and increases labor productivity. The jig design depends on the dimensions, number, and positioning of holes and on the form and use (purpose) of the part. Parts and basic jig assemblies are standardized on a large scale in order to reduce jig manufacturing costs.