DISENGAGABLE REAMER

摘要

A downhole tool (10) for use in the removal of burrs or other unwanted material from an inner surface of a pipeline, well casing or other tubular. The toll has a plurality of milling elements (32), which may be biased against the surface or retracted from the surface to disengage the toll from the tubular. A drop ball mechanism with a fluid by-pass is described for disengaging the milling elements.