True rotational centerlines may be referenced quickly and accurately with the model 284-M spindle mirror. It is designed to attach magnetically to the end of a shaft or spindle. The mirror has both a 100% reflecting surface and a multiple filar/bi-filar target printed on the surface. Translation adjustments (four laterally opposing screws) are provided to set the target concentric to the center of rotation, while angular adjustments (three spring-loaded screws at 120°) set the mirror precisely perpendicular to the shaft's rotational centerline. By setting an optical instrument to the mirror, precise extension of the shaft rotational axis is ensured.

The 284-M mirror provides a reference LOS (line of sight) on rotational axes such as drive lines, gearbox output shafts, ship's propeller shafts, generator centerlines, etc. Once an instrument is aligned with the rotational axes, various tasks may be performed to relate or evaluate the position of other items (such as machine ways, bearing journals, bores, etc.) to the original rotational axis.

Note: The rotational shaft may be turned manually during the alignment process but this unit cannot be rotated under power!