High speed drill reamer

A drill/reamer bit having a pair of spiral flutes separated by two webs, said webs terminating generally at the cutting end of said bit in diametrically opposite geometries and constituting:

• a drill portion, and a stepped reamer portion, said drill portion having first, second, third and fourth facets,
• primary and secondary drill cutting edges defining two edges of said first facet, said primary drill cutting edge and the bit axis defining a plane in which the primary drill cutting edge gently slopes from the point of concentricity toward the shank of the bit,
• said secondary drill cutting edge intersecting said primary drill cutting edge at an obtuse angle and being generally parallel to and in the plane of the trailing edge of said first facet, said trailing edge being contained in a plane of the bit axis,
• said first facet being angled from said trailing edge away from the bit shank thus to present a positive rake angle toward material being drilled, said trailing edge of said first facet being contained in the plane of said second facet, said second facet being angled from said first facet trailing edge rearwardly toward the bit shank at an angle which is greater than the angle of said first facet,
• the trailing edge of said second facet being in a plane containing the bit axis and constituting an edge of the plane constituting the third facet, the trailing edge of said third facet terminating at said flute surface,
• said drill primary cutting edge being contained in and constituting an edge of the plane of said fourth facet, another edge of which facet bisects said drill primary cutting edge and terminates at said flute surface,
• said reamer portion constituting a step defined by a smooth circumferencial wall which is parallel to the bit axis,
• the floor of said step constituting an annular surface extending between the base of said wall and the outer surface of the bit,
• and at least one relief in said floor intersecting with said flute surface thus to constitute a reamer cutting edge.

A drill/reamer bit having a pair of spiral flutes separated by two webs, said webs terminating generally at the cutting edge of said bit in diametrically opposite geometrics and including:

• a drill portion, and a reamer portion
• said drill portion having first, second, third, and fourth facets,
• primary and secondary drill cutting edges defining two edges of said first facet, said primary drill cutting edge and the bit axis defining a plane in which the primary drill cutting edge slopes slightly toward the shank of the bit,
• said secondary drill cutting edge intersecting said primary drill cutting edge at an obtuse angle and being generally parallel to and in the plane of the trailing edge of said first facet, said trailing edge being contained in a plane of the bit axis and angled at an included angle of approximately 116.+-.2 degrees,
• said first facet being angled from said trailing edge away from the bit shank at from approximately 2 to approximately 5 degrees, thus to approach material being drilled with a positive rake angle,
• said trailing edge of said first facet being contained in the plane of said second facet, said second facet being angled so that a curved line therein concentric with said bit axis is angled with respect to a reference plane perpendicular to said axis at an angle of approximately 12.+-.2 degrees,
• the trailing edge of said second facet being in a plane containing the bit axis and constituting an edge of the plane constituting said third facet,
• the trailing edge of said third facet terminating at said flute surface, and being angled with respect to the bit axis,
• said drill primary cutting edge being contained in and constituting an edge of the plane of said fourth facet, another edge of which facet bisects said drill primary cutting edge and terminates at said flute surface, said fourth facet being angled with respect to the drill axis at an angle of approximately 19 degrees,
• said reamer portion constituting a step defined by a circumferential wall which is radially relieved with respect to the bit axis and parallel thereto, the floor of said step constituting an annular surface perpendicular to the bit axis and extending between the base of said wall and the outer surface of the bit,
• said floor intersecting with said flute surface thus to constitute a reamer cutting edge,
• said reamer cutting edge being contained in a plane of first relief which is angled toward said shank with respect to a reference plane perpendicular to the bit axis of at least approximately 2 degrees,
• the trailing edge of said first relief contained in a plane which slopes with respect to said reference plane at least approximately 5 degrees toward the bit shank,
• said flutes being angled with respect to the bit axis at from approximately 81/2 degrees to approximately 23 degrees, said being being made substantially of micrograin tungsten carbide.