| 摘要 |
PURPOSE: To avoid damage of a wall front surface in the range of a drill hole opening to be generated by a rigid stopper, by providing an elastic damping member on a depth stopper. CONSTITUTION: A depth stopper 10 is constituted of a collar 2, a washer 32 and a damping member 4, and the depth stopper specifies the maximum advancing depth of a drill 1 in relation to a stone building. When the contact surface 1 of the damping member 4 is brought into contact with the wall surface 12 of the stone building 13, the drill 1 is attached to an impact drilling machine, and it can be turned sideways to from an undercut at the hole bottom. By this turning movement, the collar 2 is alternately inclined sideways, and the damping member 4 is slightly and elastically deformed. In impact-drilling, impact to be transmitted from the impact drilling machine to a shank of the drill 1 is considerably damped when the damping member 4 is allowed to abut to the wall front surface, and therefore, damage of the wall front surface in the range of a drill hole opening can be reliably avoided. |
