Soft Foot
Soft foot is a condition where one or more machine feet do not sit evenly on the base, causing frame distortion when hold-down bolts are tightened.
What this term means in maintenance
Soft foot is a condition where one or more machine feet do not sit evenly on the base, causing frame distortion when hold-down bolts are tightened.
Types of soft foot
Common conditions include:
- Parallel soft foot
- Angular soft foot
- Induced soft foot
- Excessive shimming
- Debris beneath feet
- Damaged base
Practical example
A motor foot lifts when its bolt is loosened, indicating the machine is distorted when tightened.
Consequences
Soft foot can cause:
- Alignment instability
- Frame distortion
- Vibration
- Bearing stress
- Electrical air-gap problems
- Cracked feet
Correction
Clean surfaces, inspect the base, measure foot movement, and use correct shimming.
Common mistake
Completing shaft alignment without checking soft foot can produce readings that change after tightening.
Related concepts
Related maintenance terms
Keep exploring connected CMMS, reliability, and maintenance planning terms.
Shaft Alignment
Shaft alignment is the adjustment of connected rotating-machine shafts so their centerlines operate within approved offset and angular tolerances.
Laser Alignment
Laser alignment is a shaft-alignment method using optical measurement devices to calculate and guide machine-position corrections.
Mechanical Looseness
Mechanical looseness is excessive movement caused by inadequate fastening, worn fits, structural weakness, clearance, or poor support.
Glossary FAQs
- What is soft foot?
Uneven machine-foot contact causing frame distortion when bolts are tightened.
- What problems can it cause?
Unstable alignment, vibration, frame distortion, bearing stress, and cracked feet.
- How is it corrected?
Clean and inspect the base, measure foot movement, and use correct shimming.