Abstract: A device attachable to a milling machine vise for positioning a workpiece in the opening between vise jaws. A rigid bar has means for quickly and accurately clamping the positioning device to parallel sides of a precision vise of standard width. An adjustable rigid intermediate member connected to an outer end of the bar has means for clamping a workpiece contacting rod cantilevered into the vise jaw opening. The workpiece contacting rod is slidably adjusted relative to the intermediate member. It has a contact surface perpendicular to the rod axis. Positioning device surfaces of the present invention are machined parallel to a bar alignment surface. When the bar is attached to a vise, the alignment surface is clamped against the side of the vise substantially parallel to that side. In this manner the workpiece contacting surface of the rod always remains square to the workpiece holding surfaces of the vise jaws, regardless of device position adjustment.