Abstract: A cutting tool such as a drill or reamer for machining a bore in a workpiece is provided with at least one chamfered cutting edge on its distal end having an enlarged radial extent. The chamfered edge is defined between a tapered leading end, and an undercut end, and has a radial extent about 2.5% greater than the radial extent of the shaft of the tool. At least 40% of the length of the chamfered edge is substantially parallel to the axis of rotation of the tool shaft. The tapered and radially enlarged geometry of the chamfered cutting edge advantageously allows the drill or reamer to machine a bore in a workpiece formed from materials having significant spring-back characteristics, such as aluminum, titanium, or nickel alloys without sticking or galling during the machining operation, thereby greatly increasing tool life.

Abstract: A drill jig assembly for accurately supporting a drill relative to a workpiece is provided that includes a drill having a cylindrical shank, a chuck having a cylindrical exterior, and a hydraulically-operated collet for detachably gripping the drill shank, a housing tube for slidably and rotatably supporting the cylindrical exterior of the chuck, and a drill guide mounted on the distal end of the housing tube. The drill guide is formed from a carbide bushing having a pilot bore for rotatably receiving the cylindrical shank of the drill and maintaining a pilot concentric alignment between the bushing and the shank during a drilling operation. The use of hydraulic chuck in combination with the pilot bore of the carbide bushing allows the drill to accurately bore holes in a workpiece to very tight tolerances in a one-step, extend and retract drilling operation.