MYTH: “You should always do your shimming first and then make your horizontal moves.”
TRUTH: This is generally true for the final alignment after soft foot has been corrected, but is not universally true for all alignments. In fact, for the initial rough alignment, you should correct the plane with the largest misalignment first, even if this means making a horizontal move first. Reason: If you have gross misalignment, you could be binding the coupling, deflecting the shafts, and imposing undue load on the bearings. By relieving strain from excess misalignment, a truer picture of the alignment condition emerges, and you eliminate an important outside force that creates machine frame distortion (soft foot).
Therefore, the correct sequence of events in any alignment job is:
- Safety: Lockout & tag out plus clean up
- Rough Align
- Find, diagnose, and eliminate Soft Foot.
- Final Alignment: shimming first, then moves.
Download our 5-Step Shaft Alignment Procedure a simple and effective procedure for shaft alignment of rotating equipment.
Alignment by Carlos Bienes CRL