Personally, I prefer the Reverse Dial method whenever conditions will allow. There s less weight, minimizing indicator bar sag. No wild face readings due to the axial drift of shafts in sleeve bearings on either unit and it makes the possibility of the two buttons jamming one against the other obsolete. For small diameter couplings one can usually secure a more lengthy (therefore more accurate) angular reading than with the Rim and Face method.

I first heard of the Reverse Dial method in the mid-60 s. Most millwrights used graph paper for Reverse Dial work back then, but for many years now it s seldom used. The use of a graph (admittedly) is a viable method, but isn t included in this book because it s unnecessary. A seasoned millwright can pop a chalk line on most any floor, measure off some key points along said line and calculate some very close shim packs with a little head arithmetic . But when you are required to prove with absolute accuracy what shims should be added or removed from where, a gut feeling estimate just will not suffice in industry.

My step-by-step logic process (years before the formulas were written) was used to check the accuracy of a Reverse Dial electronic device which was being used by proxy for motor alignment in the Gulf of Mexico. Truth. An engineer on the platform would phone someone on shore who in turn would key in the specific variables on said machine and recommend the resulting shim pack. Then the...