Roller bit bearing failure indicator

摘要

A rotary drill bit includes a bit body that includes a plurality of upright legs that terminate in an exterior bearing surface. At least one roller cutter is affixed to a corresponding exterior bearing surface of one of the plurality of legs. The roller cutter has an exterior cutting surface and a base edge and defines an interior bearing surface that is complementary to a corresponding exterior bearing surface. At least one duct is defined by the lower surface of the lateral wall and is adjacent to at least one exterior bearing surface. A plug is disposed in the duct at a distance from the base edge one of the roller cutters so that if either the interior bearing surface or the exterior bearing surface wears beyond a threshold, the plug will cause a remotely-sensible indication of excessive bearing wear to be asserted.