Patent ID: 7681666

Claim:
An expandable reamer apparatus for subterranean drilling, comprising: a tubular body having a longitudinal axis and a drilling fluid flow path therethrough; a plurality of generally radially and longitudinally extending blade structures carried by the tubular body, the plurality of blade structures each comprising a movable blade having a lateral height and carrying cutting structures thereon, and wherein each moveable blade is replaceable by blades having a different lateral height; at least one blade-biasing element for holding the movable blades of the plurality of blade structures at an innermost lateral position with a force; and an actuation sleeve positioned along an inner diameter of the tubular body and configured to selectively allow pressure of drilling fluid within the drilling fluid flow path of the tubular body to move the movable blades of the plurality of blade structures outwardly against the force in response to an actuation device engaging the actuation sleeve at a lower end thereof below the plurality of blade structures, the actuation sleeve further comprising at least one aperture through a side wall thereof above a location for engagement of the actuation device therewith.