As part of our training program, we simulate various scenarios, to teach trainees how to see through a problem to a solution. To this end, the Soft Foot Analysis Form is a simple yet effective aid. Soft foot is machine frame distortion. It is evidenced by the movement of the machine shaft as the anchor bolts are tightened or loosened. How the shaft moves is subtle and depends upon the specific machine condition producing the casing distortion.

The Soft Foot Analysis form:

Soft Foot Analysis Form

After reading all four feet with a laser shaft alignment system mounted on the machine shafts, the form asks you to feeler gauge the airgap at each corner of the feet that have been determined to be “soft”, with the other three feet tight. Miking the outer three corners of the foot is sufficient. Filling out the form allows you to visualize a “picture” of what is going on by comparing the shape of the airgaps to each other. This in turn leads to efficient diagnosis and correction of almost every kind of soft foot.

All the laser shaft alignment tools can do is detect if a soft foot condition exists since it is observing the reaction of the shaft as a foot is loosened. However, it cannot immediately tell you how to correct the problem.

The Soft Foot Analysis Form, when used in conjunction with our “Soft Foot Find-and-Fix Infographic”, helps you to determine which foot to shim and how much, or to determine if you have a ‘Bent’ foot condition.

The complete diagnostic procedure can be found in the LUDECA Shaft Alignment Training Manual, which every trainee receives as part of a LUDECA alignment training course. Please contact us for more information.

Watch our Shaft Alignment Know-How: Soft Foot to learn about the effects and importance of measuring and correcting Soft Foot when performing shaft alignment.

Make aligning your machinery easier, start by correcting Soft Foot


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by Alan Luedeking CRL CMRP