SCREW, POWER ROTARY TOOL BIT, AND BUILDING DESIGN FITTING CONSTRUCTING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a screw whose front end does not shake, whose head portion is virtually not protruded from a screwed object and which eliminates the need for pre-machining the screwed object, and to provide a rotary tool bit and a building design fitting constructing method. SOLUTION: The screw comprises a shaft portion 11 having a thread 11a at least in part, and the head portion 12 provided on the base end of the shaft portion 11. In the head portion 12, a bottomed engaging hole 13 is formed which is fitted to a front end 21 of the bit 2 mounted on a power rotary tool. The engaging hole 13 has a polygonal cross section, and its inner face 13a is tapered with its cross section gradually smaller as tending to the front end. The engaging hole 13 is provided over between the head portion 12 and the shaft portion 11. COPYRIGHT: (C)2008,JPO&INPIT