2015-01-28

What is bent foot condition in shaft alignment?

Bent foot is the condition when the foot is touching the base on the outside portion, but the inside of the foot is bent, creating an angle between the base and the bottom of the foot. When the hold-down bolt is tightened, the foot will deflect and distort the machine frame, depending on what portions of the frame will bend. A bent foot is a type of soft foot that occurs when the bottom of foot is not coplanar, meaning that the foot slopes from one corner to another. The foot may also be bent upward so that the outside edge is not touching the base and the deflection occurs along the outside of the foot. The best way to correct bent foot is to remove the equipment and machine the foot, the base plate, or possibly both.


If the correction must be made in the field, then the shims used in alignment must be stepped to correct the slope. Depending upon the size of the foot and the amount of slope in the bent foot, 4-5 shims may be stepped to match the slope of the foot. Additional modifications to shim may have to be made for the proper slope.

If rise of foot is from the outside going in, all of the equipment feet must be machined coplanar. This type of bent foot cannot be fixed in the field. Unless the feet are machined, it will always deform when tightened.