| 摘要 |
PROBLEM TO BE SOLVED: To provide a driver bit for obtaining a shape coinciding with an engaging groove of a screw and for reliably transmitting driving force. SOLUTION: In this driver bit for a cross recessed screw, a vane part 10 capable of being engaged with an engaging hole 20 of a screw 2 and having a cross-shaped section is formed, a distance of a connection groove 14 formed between side walls of mutually adjacent vanes 13 is formed on the base part of the vane part 10 into the E size approximately equal to the boundary distance (e) between a projecting flat surface 22 of the engaging hole 20 and an engaging groove 24 of an engaging groove 23, and the distance B between facing connection grooves 14 is set to a distance approximately equal to or slightly smaller than the distance (b) between narrowest parts across the center of the engaging groove 20. Therefore, the driver bit can firmly bites between the engaging groove and the vanes. Since the vanes of the driver bit are normally in contact with the engaging wall of the engaging groove of the screw, the driver bit is not floated in relation to the screw. Damage is not easily generated on the screw and the driver bit.
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