He is most notable for his efforts to develop and market standardized theatrical stage equipment, including rigging and fire curtains.

[1] John Clancy attended the public schools, after which he found work as typesetter for the Syracuse Herald, and then as a stagehand.

[2] Having recognized the need for standardized stage equipment as a way to improve productions and safety, Clancy went into the business of manufacturing rigging in 1885.

[1] Clancy later expanded into manufacturing other specialty metal hardware, including brace irons and screw eyes, and was an executive and director of several banks.

In addition, John Clancy managed metal stamping and forging for producing military equipment in five central New York counties under the aegis of the federal War Production Board.