Fresh from a farm, Gridley worked at the Waterbury Button Co. for only a few months before James Hartness brought him to Jones & Lamson as his secretary. In 1899 he became superintendent of the Windsor Machine Co., then operating in the old Robbins & Lawrence Armory. He developed an automatic turret lathe and followed in 1907 with a four-spindle automatic screw machine built around a spindle carrier that supported the spindles between two disks mounted on a central shaft.
Later he joined with Maxwell Evarts to buy the company and they moved it into a new plant in Windsor. In 1916 they sold to National Acme (who joined the designs as the Acme-Gridley). Tiring of retirement, Gridley started the Gridley Machine Co. in New Britain, to produce a new design. In 1929, he sold to New Britain Machine, continuing as a consultant with the company until his death. Gridley held more than 60 patents on his machine designs.