While visiting a customer’s facility,  I was asked if I could provide some tips on how shims should be replaced when making a required vertical correction on a machine being aligned.

The following steps were recommended to minimize the potential for creating a soft foot:

• When possible, upon starting the alignment, replace any old, dirty, or bent shims with new precut stainless steel shims.
• Use no more than a combination of three shims to achieve the desired thickness.
• Always take the time to measure the thickness of any shims thicker than 25 thousandths with a micrometer or Vernier caliper. Shim thicknesses of 50 thousand of an inch or higher may not always be true. The shim thickness may vary by several thousands of an inch. If this is not compensated for, it will create a soft foot problem or result in a failure to meet alignment tolerances.

• If you are not familiar with the soft foot correction procedures, it is a good practice to use a laser shaft alignment system that measures and can also diagnose a soft foot problem.

Download Best Practices: Machinery Alignment Shimming