| 摘要 |
PURPOSE:To cut smoothly the inner surface of a perforated hole of wood by a method wherein a ring cutter is fixed to the tip of a chiesel edge part and the chiesel edge part is inclined in a centripetal direction. CONSTITUTION:A drill (straight shank drill) body 1 has a point 1a and chiesel edges 1b on the cutting part and besides a ring cutter (hole saw) 2 is caped by a screw 3 on the tip of the cutting part. The ring cutter 2 is nearly cylindrical, cutting edges 2a in the form of this cutter is formed on the tip part and the end of each chiesel edge is inclined 2b in the inward or centripetal direction. Marking operation is carried out by the cutting edges 2a of the ring cutter 2 and the inside of the hole is finished smoothly. |
