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 5-Step Shaft Alignment Procedure
Check out our SS Precut Shims.
by Yolanda Lopez
The customer needed to align a boiler feed pump to a fluid drive.
Before doing so, we took care of the simple but often-ignored pre alignment checks, including a thorough cleaning up of the area around the machines. The area was a mess to start with, and cleaning up allowed us to check for soft foot and start making moves immediately after taking readings, without delays.
Some of the essential clean-up and preparation tasks we performed were:
- Clean up the work area.
- Remove jacking bolt fixtures and wire brush the corrosion off them.
- Cleaning and greasing the hold down bolts and jack bolts with white lithium grease.
- Drilled and tapped new holes in the base to add jack bolts where there weren’t any.
- Replaced dirty used shims with new LAWTON precut stainless steel shims.
- Rough aligned the pump so its anchor bolts were centered in bolt holes of the feet.
This preparation work saved much time on the actual alignment, and more importantly, ensures that the next time this job must be performed the jackscrews, base and anchor bolts will be in good condition, allowing the machines to be quickly and accurately realigned.
by Carlos Bienes CRL