Patent ID: 8764355

Claim:
A step drill bit comprising: a body comprising a head, a first groove formed on the head and a second groove formed on the head, the second groove being spaced from the first groove wherein the first groove comprises a first face and the second groove comprises a second face, and a distal end extending between the first groove and the second groove; a cutting edge insert removably attached to the body where the cutting edge insert comprises a first plurality of graduated steps on a first leg and a second plurality of graduated steps on a second leg where each one of the first plurality of steps is arranged in a pair with one of the second plurality of graduated steps to define a plurality of progressively larger cutting diameters; the first leg being connected to the second leg by a groin; the first leg being positioned in the first groove and the second leg being positioned in the second groove such that the first leg is supported by the first face and the second leg is supported by the second face and the groin is supported by the distal end; and a locking collar mounted on the body and rotatable relative to the body, the locking collar comprising at least a first cam surface for engaging the cutting edge insert where rotation of the locking collar causes the first cam surface to exert a force on the cutting edge insert pulling the first leg into engagement with the first surface, the second leg into engagement with the second surface and the groin into engagement with the distal end.