A cross slide contour form milling box tool which can be applied to automatic screw machines for contour form milling desired contours on the outside of a workpiece. The contour milling tool is positioned to a transverse slide to the drive axis. The transverse slide is driven by a pin and cam groove in the face of a cam so that the contour form milling tool is positioned in accordance with the shape of the cam groove. The milling cutter is positioned in the transverse slide and rotated by an auxiliary shaft which is driven by gears from the cam shaft using an Oldham coupling to rotate while reciprocating. The workpiece is rotated relative to the contour milling tour and the desired contour is form milled on the surface of the workpiece.