October 6, 2017
The First Rule in Precision Shaft Alignment is “Don’t Assume”!
By Brad Case
This is an obvious statement and most of us know what happens when we do “ASSUME” with most things in life. However, we (The VibrAlign Trainers) see assumptions being made quite often during a precision shaft alignment.
Several years ago, I read a book titled “A Millwright’s Guide to Motor/Pump Alignment” by Tommy “T-Hammer” Harlon (available through Industrial Press). Tommy’s book deals with all aspects of dial indicator alignment which can be applied to laser shaft alignment as well. Early in his book Tommy makes a statement that struck a chord with me and I still use it today in my training classes.
To quote, “It is foolhardy to assume anything in alignment work. Therefore, never assume.”
The example conveyed in the book is of two experienced millwrights struggling with a rim and face alignment of a motor to a pump. The millwrights kept assuming they were making some sort of simple error. It was a new pump in a new construction project, the pump didn’t require mechanical seals. They also assumed the pump should be in pristine condition.
As it turns out the pump bearings were missing and though the two sets of packing allowed the pump shaft to be rotated there was axial movement or drift causing measurement errors. Once the bearings were installed, including an axial thrust bearing, the alignment went smoothly.
While this may be an extreme example of what can happen when assumptions are made during an alignment, simple assumptions such as the stationary machine’s hold down bolts are tight, when they are not, will cause issues. Ultimately leading to “alignment frustration”.
On the VibrAlign Blog there are many blogs discussing issues caused when assumptions were made. You can search the blog by your issue. For example, this link will take you to our blog for a search on repeatability issues.
Still having issues with your precision shaft alignment? Call or email us, we are here to help and telephone/email support is always free.
To close I like to quote Tommy again. “When in doubt, check. When not in doubt and the correct formula doesn’t seem to work, get in doubt and check.”