May 29, 2013
The Devil is in the Details!
By Tom Shelton
During the field alignment portion of a Fixturlaser GO Basic shaft alignment training class, we were attempting to align a 100 H.P., 3600 RPM motor to a double suction pump. Sounds easy enough!
Here’s the skinny… The pump and motor were the top set in a vertical, two unit skid made of I-beams and very flexible and we were aligning to a tight 3600 RPM tolerance of +/- 0.5 mil/1” Angular and +/- 2.0 mil Offset Misalignment at the coupling.
We worked at it for some time and took care to follow the training. The class made sure they had a good rough alignment, no soft foot and an established bolt tightening sequence to follow. We notice however, there was a particular foot causing the motor to move when tightening the hold down bolt. We checked for soft foot again… Nope it was good, we changed the slightly cupped washer…we have it now, or so we thought. It still moved when the hold down bolt was tightened. Hmm, something has to be moving!
We decided to take turns inspecting the situation and compare our observations. Only one guy caught the problem… The wedge washer below the frame was turned 90 degrees!
He corrected the washer and fifteen minutes later we had a great alignment and were packing up the GO Basic.
When trouble starts and the alignment doesn’t go as planned, you have to go back to the basics. Look critically at every possible player in the situation. You have to broaden your view from only seeing numbers on the display unit screen and step back and look at each individual element of your machine and their purpose and effect it will have on a good alignment. If it moves the laser will see it!