Abstract: A helically fluted twist drill device is disclosed for cutting materials. The device includes a cylindrical core having a first diameter, a longitudinal axis and a first and a second extremity, the second extremity defining a cutting point. At least three portions extend helically outwardly away from the core so that the portions define a second diameter. The arrangement is such that adjacent portions define therebetween a helical flute. Each of the flutes has a flute surface which is of S-shaped configuration when viewed as a cross section disposed normal to the longitudinal axis, the cross section being viewed in a direction from the first towards the second extremity. Each of the portions further defines a helical bore connected to a source of a cutting fluid for permitting a flow of the cutting fluid through the bore towards the cutting point. The arrangement is such that in use of the device, the cutting fluid conveys the materials away from the cutting point through each flute.

Abstract: A helically fluted twist drill device is disclosed for cutting materials. The device comprises a shank having a first and a second end. A cylindrical core has a first diameter and a first and a second extremity, the core extending coaxially relative to the shank and from the second end of the shank, the second extremity defining a point. At least three portions extend helically outwardly away from the core so that the portions define a second diameter. The arrangement is such that adjacent portions define therebetween a surface of a helical flute. Each of the portions further define a helical bore connected to a source of a cutting fluid for permitting a flow of the cutting fluid through the bore from the shank towards the point. The arrangement is such that in use of the device, the cutting fluid conveys the materials from the vicinity of the point through each flute towards the shank. The first diameter has a dimension within a first range which is 20-35% of a dimension of the second diameter.