Thread mill having multiple thread cutters

A milling tool for milling threads on a workpiece, the milling tool including a tool holder rotatable in an orbital path spaced radially from a milling axis, the tool holder including a cutting insert on the tool holder, the tool holder adapted for attaching to a rotatable spindle of a mill, the cutting insert including a plurality of cutting teeth on radially outward cutting face and spaced axially along a tool holder axis for milling external or internal threads on the workpiece when the holder is rotated about the milling axis while simultaneously being rotated about the tool holder axis, the milling tool further comprising:

• the tool holder having a slot therein, the slot defining a generally rectangular insert cavity for receiving the cutting insert and extending radially outward to an outer side surface of the tool holder, and an axially elongate tool holder groove in communication with a side face of the generally rectangular insert cavity;
• a stop pin for fitting within a stop pin hole within the tool holder, the stop pin having a pin axis extending radially outward to an outer side surface of the tool holder, the stop pin defining a stop surface thereon;
• the cutting insert defining a substantially rectangular plate formed from a tungsten carbide material and including the radially outward cutting face with the axially spaced cutter teeth thereon, an end face for engagement with the stop surface on the stop pin for axially positioning the insert with respect to the tool holder, and an axially elongate insert groove extending from a side face of the rectangular plate;
• an elongate pin and for fitting within the tool holder groove and the insert groove;
• and
• a plurality of securing members for applying a force to the elongate pin for pressing the pin against the cutting insert and thereby fixing the position of the cutting insert on the tool holder.

The method of cutting threads on a workpiece with a cutting tool, the cutting tool including a tool holder having a cutting insert thereon, the cutting insert including a plurality of radially outward cutting teeth spaced along the tool holder axis for cutting threads on the workpiece, the method comprising:

• providing a slot in the tool holder, the slot defining a generally rectangular insert cavity for receiving the cutting insert and extending radially outward to an outer side surface of the tool holder;
• providing a stop surface at an axially rearward end of the insert cavity and an axially elongate tool holder groove in communication with a front side face of the generally rectangular insert cavity, a rear side face of the generally rectangular insert cavity being opposite the front side face, and a radially inward back surface of the generally rectangular insert cavity, the elongate tool holder groove having a tool holder groove axis parallel with the tool holder axis;
• providing a cutting insert defining a substantially rectangular plate including the radially outward cutting face with the axially spaced cutting teeth thereon, the rectangular plate having an end face for mating engagement with the stop surface on the tool holder and an axial elongate insert groove extending from a side face of the rectangular plate, the insert groove having an insert groove axis parallel with the tool holder axis;
• positioning the end face of the cutting insert into engagement with the stop surface on the tool holder;
• moving an elongate pin along a pin axis parallel to the tool holder axis to fit the elongate pin within the respective tool holder groove and insert groove;
• applying a force to the elongate pin to press the pin against the cutting insert in a direction toward both the rear side face and the back surface of a respective slot and thereby fix the position of the cutting insert on the tool holder;
• and
• rotating the tool holder in an orbital path spaced radially a uniform distance from a milling tool axis while simultaneously rotating the tool holder about the tool holder axis for cutting the threads on the workpiece.