| 摘要 |
A Phillips type screw driver bit in which the four radially extending vanes at the bit end of the screw driver shank are provided with wall portions near the apex of the bit that will contact with the adjacent wall surfaces in the cruciform slot in the screw when the bit is inserted into the cruciform slot. The point of novelty lies in providing the wall portions of the vanes with relieved areas that will be spaced from the adjacent wall surfaces in the cruciform slot that lie at the top surface of the screw head. In other words, when the screw driver bit is seated in the cruciform slot in the screw, the relieved portions of the side walls of the vanes will be spaced from the adjacent surfaces of the cruciform slot so that there can be no contact between these opposed surface portions and the upper portion of the cruciform slot (in the screw head) cannot become marred or damaged.
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