1. A TOOL FOR FORMING A HELICAL GROOVE ABOUT THE INNER SURFACE OF A TUBULAR MEMBER COMPRISING AN ELONGATED MEMBER INCLUDING A FIRST WORK ENGAGING PORTION AT ONE END AND A SECOND WORK ENGAGING PORTION SPACED THEREFROM, SAID FIRST WORK ENGAGING PORTION INCLUDING A METAL CUTTING SURFACE HAVING A RECESS OF SUBSTNATIAL LENGTH AND VARYING DEPTH INCLINED RELATIVE TO THE LONGITUDINAL AXIS OF THE MEMBER, THE DEEPEST PART OF SAID RECESS OCCURRING AT THE END OF THE MEMBER, SAID METAL CUTTING SURFACE HAVING SPACED ROWS OF TEETH ARRANGED SO THAT ONE OF THE EDGES OF THE INCLINED RECESS FORMS A WORK CUTTING EDGE.