Expandable raise bit

摘要

A bit is provided that includes a bit body defining a bit axis of rotation. Primary cutter means are positioned on the bit body for disintegrating the formations out to a first radial distance from said bit axis of rotation. Secondary cutter means are adapted to be connected to the bit body and selectively located in a first position for cutting between said first radial distance and a larger second radial distance and selectively located in a subsequent position between said first radial distance and an even larger subsequent radial distance. Expansion means are provided to be located between said secondary cutter means and said bit body for locating said secondary cutter means in said subsequent position.