Abstract: A compliant device holding the work-piece part in an assembly, grinding, sanding or polishing process has a rotational compliance which matches the rotational compliance of a compliant device holding the work tool part or part to be assembled with the receiving part. A contact force between the two parts thus causes each part to rotate the same amount about any axis perpendicular to the direction of relative motion between the two compliant devices, thereby preserving the relative orientation of the two parts.