Combined drilling and chamfering tool - is in two versions with chamfering edges at bottom of drill chuck jaws or on tool bit hinged in recess of twist drill flute

摘要

In the first version fo the tool the jaws of the drill chuck have inclined cutting edges which are lowered onto the corner of the hole to chamfer the corner when the drill has penetrated the work. In a second version of the tool the chamfering tool bit is hinged in a recess machined into the flute of the twist drill. During drilling the tool bit pivots away from the hole wall into the recess. To chamfer the corners of the hole the tool bit is carefully positioned at the hole corners and the drill rotated in reverse. ADVANTAGE - Drilling and chamfering can be done in one operation, thereby saving time and cost.