NOVELTY - The assembly has a push sleeve (206) axially moved relative to a tubular body (202) to move a reamer blade (204) into an extended position. An activation module comprises an outer tubular body rigidly coupled to the tubular body of an expandable reamer module (200). The tubular body includes an inner bore. An activation unit e.g. rod, is partially placed within the inner bore of the tubular body. A longitudinal end of the activation unit is coupled to the sleeve to axially move the sleeve relative to the body of the reamer module in responsive to axial movement of the activation unit.    USE - Expandable reamer assembly for reaming a subterranean borehole and a bottom-hole assembly (claimed) used to extract oil and gas and geothermal heat from a subterranean formation.    ADVANTAGE - The assembly is designed such that manufacturing and maintaining of the expandable reamer module can be less expensive due to a reduced number of components and reduced complexity. The assembly provides single design of the expandable reamer module to be used with a less expensive mechanical activation module, thus providing potentially higher performance electronic and hydraulic activation device without changing design of the expandable reamer module. The assembly allows spacers to be removed before to coupling the activation unit to the sleeve with a joint structure if threads on the longitudinal end of the tubular body of the expandable reamer module are re-cut or length of the tubular body is shortened, so that the shortened length of the tubular body can be compensated for and difficulties of re-coupling the activation unit to the sleeve can be reduced or avoided.    DETAILED DESCRIPTION - The expandable reamer module is a slave unit. The sleeve comprises an outer surface selected from a group consisting of carbide material, tungsten carbide material, nitride material, chrome material, nickel plating material and cobalt-chromium alloy material. INDEPENDENT CLAIMS are also included for the following:    (1) a bottom-hole assembly    (2) a method for using expandable reamer modules.    DESCRIPTION OF DRAWING(S) - The drawing shows a side cross-sectional view of an expandable reamer module in a deactivated position.    Expandable reamer module (200)    Tubular body (202)    Reamer blade (204)    Push sleeve (206)    Joint structure (216)