A boring machine includes a power unit (10) having a housing (100), a drive member (118) for engaging a boring bar (14), and a motor (117) for driving the drive member (118) to rotate relative to the housing (100). The boring machine also includes a bearing assembly (22) comprising an inner bearing member (32) defining a passage through which the boring bar (14) extends, and an outer bearing member (33) in which the inner bearing member (32) is fitted in a manner permitting angular movement of the inner bearing member (32) relative to the outer bearing member (33) about axes perpendicular to the axis of the passage defined by the inner bearing member (32). In use, the bearing assembly is attached to a workpiece (6) in a manner preventing movement of the outer bearing member (33) relative to the workpiece (6), and a collapsible torque transmission linkage (44) connects the housing (100) of the power unit (10) to the outer bearing member (33), whereby the power unit (10) is held against rotation relative to the outer bearing member (33).