Fly Off the Handle

A real, dangerous hazard of working with hand tools. Wood shrinks and swells with humidity and temperature, and an axe head that had loosened on its handle could, with one hard swing, detach entirely and go flying, a genuine occupational danger of frontier and farm life. The figurative sense, describing a person suddenly losing control the same way, began appearing in American English print by the 1830s, with an early example in Thomas Haliburton's The Attaché; or, Sam Slick in England (1843-44).