Lathe tool holder with interchangeable flat polygonal bits fixed by means of a screw

Claim 1

A CUTTING TOOL COMPRISING IN COMBINATION, AN EXCHANGEABLE TOOL BIT BEING FORMED BY A HEXAGONAL PLATE HAVING AN UPPER FACE AND A LOWER FACE SUBSTANTIALLY PARALLEL TO EACH OTHER, AND SIDE FACES EXTENDING BETWEEN SAID UPPER AND LOWER FACES SUBSTANTIALLY PERPENDICULAR THERETO AND INTERSECTING SAID UPPER AND LOWER FACES ALONG EDGES OF EQUAL LENGTH, EVERY SECOND ONE OF SAID EDGES OF SAID LOWER AND UPPER FACES BEING FORMED AS A CUTTING EDGE WITH A CHIP GUIDE GROOVE EXTENDING SUBSTANTIALLY PARALLEL THERETO AND BETWEEN THE EDGES ON THE RESPECTIVE FACE ADJACENT SAID CUTTING FACE, SAID CUTTING EDGES INCLUDING WITH ONE OF SAID EDGES ADJACENT THERETO AN ANGLE OF LESS THAN 90*, SAID TOOL BIT BEING FORMED WITH A BORE EXTENDING BETWEEN SAID UPPER AND LOWER FACES SUBSTANTIALLY PERPENDICULAR THERETO AND BEING COUNTERBORED AT EACH OF SAID FACES; A TOOL HOLDER HAVING A FRONT END AND BEING FORMED THEREIN WITH A CUTOUT IN WHIH SAID TOOL BIT IS LOCATED, SAID CUTOUT BEING DEFINED BY A BOTTOM FACE AND PAIR OF SIDE FACES SUBSTANTIALLY PERPENDICULAR TO SAID BOTTOM FACE AND INCLINED TO EACH OTHER AT AN ANGLE EQUAL TO THAT BETWEEN SIDE FACES OF SAID TOOL BIT AND SAID TOOL BIT ABUTTING WITH SIDE FACES THEREOF AGAINST SAID SIDE FACES OF SAID CUTOUT, SAID TOOL HOLDER BEING FORMED WITH A THREADED BORE ALIGNED WITH SAID BORE IN SAID TOOL BIT AND EXTENDING FROM SAID BOTTOM FACE SUBSTANTIALLY PERPENDICULAR THERETO INTO SAID TOOL HOLDER; AND A SCREW FOR FASTENING SAID TOOL BIT TO SAID TOOL HOLDER AND EXTENDING THROUGH SAID BORE IN SAID BIT INTO SAID THREADED BORE WITH THE HEAD OF SAID SCREW LOCATED IN THE COUNTERBORE FORMED AT SAID UPPER FACE, SAID BORE AND COUNTERBORE HAVING A DIAMETER GREATER THAN THAT OF SCREW SHANK AND HEAD, RESPECTIVELY, SO THAT CUTTING PRESSURE ON SAID BIT WILL BE TAKEN UP BY SAID SIDE FACES OF SAID CUTOUT WITHOUT SUBJECTING SAID SCREW TO BENDING STRESSES.