This is one of those odd ball problems that can slip in on one s blind side and be staring him square in the face just when he thought he knew alignment work. Requiring direct ratio and proportion arithmetic much the same as other facets of alignment, yet presenting a rather unique objective, it has to be approached with an equally unique mathematics format in mind.

To begin with, field coil and armature alignment isn t always expected to be precise alignment. In large units the inside surfaces of (some) generators and motors tend to form something sub-standard to what s regarded a perfect circle. This is probably most often found in low R P M units.

What is frequently needed then is simply a good average of armature/field coil clearance that leaves the rotating and fixed elements sharing (as near as possible) a common, concentric centerline throughout the affected lengths of the two units (the two units being, of course, the outside diameter of the rotating element and the inside diameter of the static field coil).

Traditionally, the field coil housing will be set in its approximate position and elevation. Then the rotating element will be inserted into position and aligned to its driving or driven unit as applicable. (Traditional alignment procedures will suffice for this part.) At this point the imaginary axis of the field coil is very unlikely to share a common concentric centerline with the rotating element.

Pursuant to this probability, the field coil housing will have to be...