| 摘要 |
In one aspect, a drill bit is disclosed that in one embodiment includes a bit body that has a longitudinal axis, a blade of a selected length on a side of the bit body and substantially along the longitudinal axis, and a movable member associated with the blade that extends from a retracted position to a selected extended position along the longitudinal axis, thereby effectively extending the length of the blade when the movable member is in the selected extended position. |
