An apparatus and method for installing and removing a tool on a chuck connected to a robot arm. The chuck has a mandrel with two parallel flat sides and two protruding flanges. The tool has a tool coupling member which is supported and held against rotation by a support plate. The tool coupling member is cylindrical and has two lugs spaced apart to allow the flat sides of the mandrel to pass, but to lock over the flanges of the mandrel when the mandrel is rotated relative to the tool coupling member. A cam follower on the chuck follows a guide slot in the support plate to cause the mandrel to rotate relative to the tool coupling member. The cam follower also causes a key on the chuck to mate or disengage a key slot on the tool coupling member.