Abstract: A step drill bit includes a cutting head portion with a rear end coupled to a shank portion. The cutting head portion incudes a front cutting tip, a plurality of steps of progressively increasing diameter from the cutting head to the rear end portion. Each step includes a conical tapered portion that flares radially outward from the axis and a generally cylindrical portion that extends axially rearward from the tapered portion. A flute extends through the steps generally parallel to or helically relative to the axis. Primary and secondary cutting edges are formed at junctions between the tapered portions and the generally cylindrical portions and the flute. A depth stop flange extends radially outward from a rearmost step and has a diameter greater than the diameter of the cylindrical portion of the rearmost step. A deburring recess is disposed within or between one of the steps and includes a deburring edge at a junction between the deburring recess and the flute to remove burrs from an edge of a hole.

Abstract: A step drill bit includes a body with a plurality of cylindrical steps of increasing diameter from a front end toward a rear end, a flute extending from the front end toward the rear end, and cutting edges at junctions between each step and the flute. A cutting insert with a hardness greater than the hardness of the body is coupled to the front end portion and at least partially defines a cutting head portion. The cutting head portion includes a center cutting tip, a cutting edge extending radially outward from the cutting tip, a rake face extending from the cutting edge toward the rear end portion, a relief face extending from the cutting edge in a circumferential direction opposite a rotational cutting direction of the drill bit, and a chip clearing recess in communication with the flute, with the rake face facing the chip clearing recess.