Abstract: A tool storage mechanism is disclosed wherein a tool storage magazine is mounted by a pivotal connection to a vertically movable tool slide. The tool slide also carries a horizontally movable tool slide carrying a rotatable tool for operating on a workpiece which moves in the third mutually perpendicular direction. The carried tool slide retracts to a tool change position whereat a tool changer will interchange a tool in the tool spindle with one in a socket of the tool storage magazine. Accordingly, the tool storage magazine moves up and down vertically with the first tool slide but has its own second drive means separate from the first drive means of the first slide. This second drive means is close to the nominal center of mass of the tool storage magazine but this center of mass changes as the magazine moves to present selected tools to the tool changer.