An apparatus adapted to be installed for rotation on a machine and having a portion for receiving and supporting a working assembly such as a honing mandrel and a mounting adapter therefor including a mounting member for attaching the apparatus to a machine a first member having a first portion at one end for attaching to the mounting member and a tubular portion at the opposite end having a first bore of predetermined diameter adjacent to the inner end thereof and a second bore portion of greater diameter extending to the opposite end thereof, a second member positioned extending into the bore in the first member from the opposite end thereof and having an internal bore therein, the second member being constructed to permit some bending thereof, a portion on the outside diameter of the second member being the same as the predetermined diameter of the first bore portion of the first member for engagement therewith, the rest of the second member being of less diameter than the second bore portion, first and second pairs of opposed radially extending threaded members mounted in the first member adjacent the opposite end thereof for engagement with the second member and adjustable to establish the angular orientation of the opposite end portion of the second member, and other pairs of opposed radially extending threaded members in the first member engageable with the mounting member and adjustable to relocate the mandrel axis to compensate for mandrel wear.