Precision Brand Products, Inc.

Sof’ Shoe® Shim Questions

Where can I view your online Sof Shoe® Shim

You can view our Sof Shoe® Shim products in our online catalog.

Is there a way for me to view how Sof' Shoe® shim works?

Yes, Precision Brand Products, Inc. has an on-line Power Point presentation which tells you more about Sof Shoe® shim. Click here to view it.

What is Sof’ Shoe® shim?

Sof’ Shoe is a uniquely blended elastomer shim which fills irregular gaps associated with angular soft foot. It is used in conjunction with Precision Brand® stainless steel Slotted Shims.

What is Angular Soft Foot?

Angular Soft Foot is a condition that occurs when a gap under a motor’s foot is “non-parallel” to the mounting base. Because of this gap, the foot, when tightened, is forced to seat itself to whatever angle allows it to make total surface contact. As a result of this seating, stresses are created in the motor’s foot that transfer through the motor’s “leg” and into the housing.

What is the difference between Soft Foot and Angular Soft Foot?

The first step during an alignment is to check the motor’s feet for gaps. Each foot is checked above and below the shim pack with feeler gages to determine if the gap between the foot and base is parallel. A parallel gap indicates regular Soft Foot. A non-parallel, irregular gap means Angular Soft Foot is present.

Why is Angular Soft Foot a problem?

If a motor’s foot is not parallel to the base when the hold-down bolts are tightened, then the motor’s housing will become twisted. This additional stress distorts the bearings and shaft. In order to alleviate this stress, all feet of the motor must sit parallel and have complete surface contact to the base. A motor that is accurately aligned and relieved of external stresses, will run smoother with less vibration, and will be more likely to attain optimum life expectancy.

Why can't I always get rid of Soft Foot?

You may be trying to correct for regular Soft Foot when in reality Angular Soft Foot exists. In many instances both a dial indicator and/or a laser measure a rise but these instruments cannot tell if it is a flat rise or angular rise. A parallel gap means regular Soft Foot exists, a non-parallel, irregular gap (only detectable by measuring with feeler gages) means Angular Soft Foot exists. The problem of distinguishing between Angular Soft Foot and regular Soft Foot is most obvious when the feet have been shimmed with the proper amount of shims, but now the instruments indicate that the problem has not gotten any better or has even become worse. This will give you the feeling of “chasing your tail” by re-shimming each foot numerous times and not getting any closer to eliminating the Soft Foot. Even with sophisticated, expensive laser alignment systems, you still must rely on feeler gages to measure each corner of every foot to detect an angular gap.

What is a common characteristic of Angular Soft Foot?

Another hint that Angular Soft Foot may be present is when a motor seems to move or “walk” horizontally whenever the hold-down bolts are loosened or tightened during an alignment. Usually, a maintenance worker can finesse the motor into proper alignment just by re-tightening the hold-down bolts in a particular pattern. What this individual may not realize is that the motor is “walking” because a foot is being forced to bend to make total surface contact to the mounting base. This will cause internal twisting and high vibration of the motor.

How has Angular Soft Foot been corrected in the past?

Typically, the most common method is to “step shim” the irregular gap by stacking very thin graduated shims. Unfortunately, even if the “step shim” is properly fitted, any horizontal adjustment to the motor during alignment can change the gap to be shimmed, making the “step shim” worthless. Also, if after start-up any one of the individual “steps” in the shim happen to slip out of place, a “domino effect” may occur causing the other shims to move. Two other types of correction are re-machining the motor’s foot or base, or pouring epoxy onto the base. All of these methods are more costly and time consuming when compared to Sof’ Shoe®.

How does Sof’ Shoe® shim work?

Sof’ Shoe® shims come in two thicknesses: blue is .020″, yellow is .045″. The blue Sof’ Shoe® will absorb up to .010″ irregularity; the yellow Sof’ Shoe will absorb up to .020″ irregularity. After determining the amount of the angularity that is present under your foot, you select the proper Sof’ Shoe thicknesses. The Sof’ Shoe® shims are normally installed above and below the shim pack creating a complete foot to base contact. Sof’ Shoe® with its unique properties, cold flows into angular gaps allowing for complete surface contact between a motor’s foot and base. Sof’ Shoe® shims permanently set over a 10 to 14 day period and because of their unique formulation always provide continuous support.

How do I learn more about Sof’ Shoe®?

Precision Brand® offers various comprehensive brochures and worksheets outlining the installation procedures and advantages of Sof’ Shoe® shims. Simply call the PBP customer service department at (630) 969-7200 or e-mail us at pbsales-cust-service@pbrand.com and ask for these materials.