Abstract: An apparatus for threading a work piece on a standard engine lathe is disclosed. In the preferred embodiment, the apparatus utilizes an accessory supporting the cutting point on the cross feed of the carriage with a proximity linkage. The proximity linkage determines when the lead screw has carried the carriage to the limits desired for its travel. It releases by use of a movable cam a spring retract mechanism which withdraws the accessory and, hence, the tool point, from a cutting position adjacent to the work piece. Alternate embodiments are disclosed including a positioned set of cams on linkage rods and an alternate form of hand operated, hand reset, retractable apparatus.