COMBINED REAMER AND DRILL BIT STABILISER

摘要

The invention is a combined reamer and stabiliser for attachment to a drill string that includes an elongate rod (13) securable at its upper end to a drill rod and that is also securable at its lower end to either a drill rod or a drilling tool. The elongate rod (13) has a stabiliser (11) that comprises a portion of the elongate rod having a large diameter that is matched to the gauge diameter of the hole being drilled. A reamer (12) is located below the stabiliser (11) (in the direction of drilling) that comprises cutter means (18) where a first portion of the cutter means (18) has an effective cutting diameter that matches the gauge diameter of the hole being drilled and where the remaining portion of the cutter means (18) has an effective cutting diameter that is less than the diameter of the first portion. The combination of the reamer (12) with the stabiliser (11) that gradually increases the diameter of the hole being drilled to gauge diameter results in a far greater degree of stabilisation of either drill rods or a drilling tool.