Reverse cutting expansion tap

A reverse thread cutting expansion tap comprising:

• (a) a body hving a head on one end and a bore therethrough;
• (b) a plurality of angularly tapered threads formed into the body on the end opposite the head, the threads are located on resilient fingers which extend forward from the body having outer surfaces forming a relatively small angle with the axis of rotation of the tap, said threads having a plurality of parallel flutes therebetween, further, said threads interface with existing threads in a workpiece cutting damaged threads therewith;
• (c) wrenching means on said head providing a gripping surface for hand tools to rotate said tap within a threaded hole in a workpiece;
• (d) a shoulder stop disposed between said head and said tapered threads for limiting the allowable penetration of the threads into a workpiece by creating an obstruction therewith;
• (e) an expansion forcing cone, having a threaded hole in the center thereof, contiguously engaging said bore in the body on the tapered threaded end;
• and, a truncated body having a plurality of alignment ribs protruding from the angular edge of the cone, so as to abutt with each flute in the tapered threads preventing rotation of the cone while said capscrew is rotated urging the tapered threads from an angular taper to a parallel thread relationship;
• and,
• (f) a tensioning capscrew having threads on one end and head on the other, inserted into said bore in the body threadably engaging said forcing cone in such a manner as to expandably urge said tapered threads from an angular taper to a parallel thread relationship by the rotation of said capscrew into the forcing cone, moving the intersection of the cone with the bore end outwardly forcing the threads into parallel alignment, for cutting threads when the tap is inserted into a workpiece, expanded, and removed in reverse rotation.

A reverse thread cutting expansion tap comprising:

• (a) a body having a head on one end and a bore therethrough;
• (b) a plurality of angularly tapered threads formed into the body on the end opposite the head, the threads are located on resilient fingers which extend forward from the body having outer surfaces forming a relatively small angle with the axis of rotation of the tap, said threads having a plurality of parallel flutes therebetween, further, said threads interface with existing threads in a workpiece cutting damaged threads therewith;
• (c) wrenching means on said head providing a gripping surface for hand tools to rotate said tap within a threaded hole in a workpiece;
• (d) a shoulder stop diposed between said head and said tapered threads for limiting the allowable penetration of the threads into a workpiece by creating an obstruction therewith;
• (e) an expansion forcing cone, having a threaded hole in the center thereof, contiguously engaging said bore in the body on the tapered threaded end;
• and,
• (f) a tensioning capscrew having threads on one end and a head on the other, inserted into said bore in the body threadably engaging said forcing cone in such a manner as to expandably urge said tapered threads from an angular taper to a parallel thread relationship by the rotation of said capscrew into the forcing cone, moving the intersection of the cone with the bore end outwardly forcing the threads into parallel alignment, for cutting threads when the tap is inserted into a workpiece, expanded, and removed in reverse rotation, said capscrew further having a shoulder on the threaded end and a socket on the head end, said shoulder having a location so positioned as to limit the travel of said forcing cone to open said tapered threads into exact parallel alignment and said socket to provide an attachment point for a hand held wrench to be inserted for manual operation thereof.