Jig borer

The jig borer is a type of machine tool invented at the end of World War I to make possible the quick-yet-very-precise location of hole centers. It was invented independently in Switzerland and the United States. It can be viewed as a specialized species of milling machine that provides tool and die makers with a higher degree of positioning precision (repeatability) and accuracy than those general machines had provided. Although capable of milling, a jig borer is more suited to highly accurate drilling, boring, and reaming, where the quill or headstock does not see the significant side loading as it would with mill work. The result is a machine designed more for location accuracy than heavy material removal.