A ballscrew thread forming tap including a complete thread portion and a leading portion is to be screwed into a prepared hole provided in a workpiece so as to cause an inner circumferential surface of the prepared hole to be plastically deformed for thereby forming a ballscrew thread corresponding to an external thread provided in the complete thread portion. A screw thread of the external thread has a leading flank and a trailing flank, which are to be positioned on a front side of the trailing flank and on a rear side of the leading flank, respectively, when the ballscrew thread forming tap is screwed into the prepared hole. The screw thread is formed such that, in the leading portion, an indentation depth into the workpiece made by the leading flank is smaller than an indentation depth into the workpiece made by the trailing flank.

A tap and chaser are provided each having a cylindrical tool receiver connected to a threading section by a shaft. The receiver and shaft are of diameters sufficiently small to enter the bore hole and distribute any off axis load onto a number of internal threads of the bore hole to dissipate loading. The threaded section includes a group of longitudinal flutes. Each of the lands of the threaded section includes a novel cutting face, tooth angle and rake angle to advantageously allow for threading deep blind holes.

A tap and chaser are provided each having a cylindrical tool receiver connected to a threading section by a shaft. The receiver and shaft are of diameters sufficiently small to enter the bore hole and distribute any off axis load onto a number of internal threads of the bore hole to dissipate loading. The threaded section includes a group of longitudinal flutes. Each of the lands of the threaded section includes a novel cutting face, tooth angle and rake angle to advantageously allow for threading deep blind holes.

A repairing tool for an electric wire threading head for pressing and squeezing a drawing-in wire of the electric wire includes a first holding part, a second holding part opposite to the first holding part, and two positioning bolts for fastening the first holding part and the second holding part. A first half screw hole and a second half screw hole are protrudingly formed on the first holding part and the second holding part to form a complete screw hole. The drawing-in wire is pressed and squeezed through the positive rotation or reverse rotation of the repairing tool to form an external screw thread part and increase a screw thread area, and the surface of the external screw thread part is applied with instant dry adhesive and rotated into a pulling head, so that the drawing-in wire is closely adhered to the pulling head and tensile strength is improved.

A repairing tool for an electric wire threading head for pressing and squeezing a drawing-in wire of the electric wire includes a first holding part, a second holding part opposite to the first holding part, and two positioning bolts for fastening the first holding part and the second holding part. A first half screw hole and a second half screw hole are protrudingly formed on the first holding part and the second holding part to form a complete screw hole. The drawing-in wire is pressed and squeezed through the positive rotation or reverse rotation of the repairing tool to form an external screw thread part and increase a screw thread area, and the surface of the external screw thread part is applied with instant dry adhesive and rotated into a pulling head, so that the drawing-in wire is closely adhered to the pulling head and tensile strength is improved.

A method of making a cutting tap includes: providing an elongate tap body having an axial forward end, an axial rearward end and a central longitudinal axis; securing the axial rearward end of the tap body in a grinding machine; and forming in the axial forward end of the tap body a correction grind and a main flute in one continuous grinding operation. A cutting tap made by the invention is also provided.

A method of making a cutting tap includes: providing an elongate tap body having an axial forward end, an axial rearward end and a central longitudinal axis; securing the axial rearward end of the tap body in a grinding machine; and forming in the axial forward end of the tap body a correction grind and a main flute in one continuous grinding operation. A cutting tap made by the invention is also provided.

A thread forming tap includes a screw thread formed into a male thread shape with margin portions disposed to project in radial direction and relief portions having a diameter smaller than the margin portions, the margin portions and relief portions alternatively arranged and, thread forming tap causes the margin portions of the screw thread to cut into a surface layer portion of a prepared hole formed in a work to plastically deform the surface layer portion to form a female thread, margin portions are formed into a ridge line shape with a width dimension of zero at least at a thread bottom of the screw thread, and margin portions are formed into a ridge line shape with a width dimension of zero in a range from a thread bottom of the screw thread to a position between the thread bottom and an effective diameter position of the screw thread.

A thread forming tap includes a screw thread formed into a male thread shape with margin portions disposed to project in radial direction and relief portions having a diameter smaller than the margin portions, the margin portions and relief portions alternatively arranged and, thread forming tap causes the margin portions of the screw thread to cut into a surface layer portion of a prepared hole formed in a work to plastically deform the surface layer portion to form a female thread, margin portions are formed into a ridge line shape with a width dimension of zero at least at a thread bottom of the screw thread, and margin portions are formed into a ridge line shape with a width dimension of zero in a range from a thread bottom of the screw thread to a position between the thread bottom and an effective diameter position of the screw thread.

This invention, a thread chase with a lead that acts as a smooth bore guide into a threaded hole is suitable where space is confined, and the male thread chase must be exactly aligned with the female threads, “sight unseen”, or damage to female threads may result by applying force to a misaligned thread chase, particularly where the female threads are of softer metals. The lead smooth bore also prevents shavings and other debris resulting from the cleaning from the chase, from falling into the hole that is being cleaned. A recessed tapered area between the threaded portion of this case and the lead smooth bore guide collects the shavings or cleaning residue so that when the tool is withdrawn from the hole, the shavings and cleaning residual will collect in that area and not fall into the threaded hole being cleaned.