Misalignment has been traditionally measured with precision mechanical instruments found in a machine shop. These instruments are straight edges, levels, thickness gages, micrometers, and dial indicators, and are still very useful. The very best alignments can be achieved with dial indicators just as well, and as fast, as with more sophisticated measuring instruments, like lasers.

A common machine shop method is to use a precision flat surface as a reference like a granite surface plate. A 90 -angle plate can be placed on this surface to form a right angle. Using a dial indicator, any other geometric feature, like a shaft, can be set parallel to the surface plate. Likewise, a coupling could be set and adjusted perpendicular to the shaft. Another shaft can be set to the same height as the first shaft and, using the angle plate as a reference surface, to the same horizontal distance from the angle plate. The two shafts can then be considered to be collinear, Fig. 3.17. We need to assume that the two shafts are straight and of the same diameter and round in the two planes where measurements are taken. This method could work in the field to align a pump to a motor if we had flat reference surfaces. But rarely are such good reference surfaces available on site. Generally, the only precision features available are the shafts themselves, so it makes sense to discard the reference surface method and attempt to align one shaft directly to the other.