| 摘要 |
<p>A drill bit comprising a gauge region 42 at or near a drilling end 45, and a connection means 46 for connecting the drill bit 40 to a drill motor assembly. The connection means 46 is provided to connect the drill bit 40 to a motor shaft of a drill motor assembly. By such provision, the need for a connector, e.g. a bit box, between the drill bit 40 and the end of the motor body, e.g. motor shaft, is eliminated. A neck portion 50 is provided at or near an upper end of the gauge bit 42 to allow gripping, e.g, by a bit gripper. The gauge portion 42 has a length less than or equal to approximately 1.0 times the nominal bit diameter, and typically in the range of 1 inch (25mm) to 1.0 times the nominal bit diameter ie a "short gauge bit".</p> |
