Patent ID: 8388278

Claim:
A method for arranging inserts in an indexable drill, comprising the steps of: arranging a first indexable insert and a second indexable insert at an end of a drill main body at positions where distances from a rotational center (O) differ from each other and which are separated from each other by half turn in the circumferential direction of the drill; positioning the second indexable insert at an outer side of the drill so as to project forward in an axial direction from the first indexable insert at an inner side of the drill, so that an outer-end corner of the second indexable insert engages a workpiece first, and setting a ratio between a cutting contribution (A) of a center cutting edge formed of the first indexable insert and a cutting contribution (B) of a peripheral cutting edge formed of the second indexable insert in the range of A:B=52:48 to 55:45; and arranging the first and second indexable inserts at positions where the ratio between the cutting contributions of the center cutting edge and the peripheral cutting edge is maintained within the range of A:B=52:48 to 55:45 by changing the positions where both the peripheral cutting edge and the center cutting edge are fixed when an outer diameter of the indexable drill is changed.