He received a common-school education and then became a machinist's apprentice.
Upon completing his apprenticeship, he worked at his trade in various shops in Ware and Chicopee Falls, Massachussets, and in 1832, when twenty-four years old, went to Collinsville, Connecticut, to work for the Collins Company, manufacturers of axes. He began there as a lathe hand in the repair shop but because of his unusual and mechanical aptitude very soon became foreman. He remained with this company for seventeen years, the last four as superintendent, and during this time, through his inventions and improvements in axe-manufacturing machinery and methods, he converted the Collins establishment from a primitive shop into a modern factory, thereby enabling the company to increase its business greatly and attain virtual control of the American axe market. In 1849 Root was offered positions by four different manufacturers, and accepted the superintendency of the newly established Colt Armory at Hartford, Connecticut, at a very large salary. He then removed with his family to Hartford and in the course of the next five years designed and built the Colt Armory as well as most of the machinery for it. In this plant the principle of interchangeable parts was adopted and automatic or semi-automatic machinery was substituted for most of the handwork. Even before the armory was completed in 1855, Root had devised and patented much of the automatic machinery, one of the most ingenious of his devices being a drop hammer, patented August 16, 1853. In addition, he devised machines for boring and rifling gunbarrels, for stock-turning, for splining, and for making cartridges, and worked out the whole system of jigs, fixtures, tools, and gauges. It is said that many of the machines devised by Root are still running, and are on a par in accuracy and economy of production with those produced today (1934). Every process in the Colt Armory showed his influence. It is said that his drop-hammer inventions of 1853 and 1858 put the art of die-forging on its present basis; his form of drop hammer remained in vogue until the present board drop was developed. Besides his inventions bearing on the manufacture of firearms, Root patented a cam pump (1856), designed especially for use in raising water from the Connecticut River to a reservoir from which the workmen's village built up around the armory was supplied. Upon the death of Colt] in 1862, Root became president of the armory and continued in this capacity until his death in 1865, receiving, it is said, the highest salary paid in the state of Connecticut. He was one of the ablest mechanics New England ever produced and the success of both the Collins and Colt companies was in a large measure due to him. Furthermore, many of the most famous of America's later tool builders received their mechanical training under his supervision.
Root married, first, Charlotte R. Chapin of Springfield, Massachussets, on October 16, 1832; after her death, he married Matilda Colt of Hartford, October 7, 1845. At the time of his death in Hartford he was survived by his widow and four children, one of whom was a son by his first wife.