Abstract: A machine tool including a bed for temporary attachment to a large size work piece for performing machining operations thereon. A carriage is slidably mounted on the bed ways and includes its own feed arrangement for movement of a carriage mounted column assembly. The column assembly in addition to moving along perpendicular axes may be positioned about its lengthwise axis. Entrained on column ways is a slide positioned by a column feed arrangement, the slide in turn rotatably supporting a powerhead assembly within which a cutter or boring tool is carried. Segmented locking rings permit locking of the column assembly slides in an adjusted position to permit universal presentation of the tool to a work piece. Brackets mount the tool bed in an upright position on the work piece.