Overview

Rough methods are those that do not use precision radial measuring devices like dial indicators, and do not employ a mathematical algorithm to calculate precise machine moves. Instead, the measuring devices are simple, like straight edges and feeler gages, and the movement of machines is determined by a mechanic who can visualize the correct directions and guesses at the amounts.

The results themselves are not rough. Actually, excellent alignments are achievable with these methods. The "rough" terminology is more descriptive of the trial-and-error fashion of slow convergence to a good alignment. The slow convergence is partially due to imperfect couplings. These rough methods use the coupling halves as the reference surfaces for measurement. Couplings are not perfect, nor are they mounted perfectly. Using them as references for alignment may result in good coupling alignment, but not necessarily good shaft alignment. Therefore, coupling alignment is always "rough" when using nonmachined coupling surfaces like cast surfaces or painted surfaces. However, when using precision-machined coupling surfaces as references or the shafts themselves, excellent alignments are achievable with these "rough" methods.

The rough methods use low-cost instruments for measurement, or no specialized instruments when we consider the straight-edge and feeler gages as part of a mechanic's normal tools. The success of these methods relies only on the knowledge and experience of the mechanic, and not on high-tech instruments.

The rough methods are applicable when first placing a machine onto its foundation. It can be considered as the first of three alignments. The second alignment...