In this animation, we show you how to check your machinery for soft foot (or machine frame distortion) issues, and how to fix the problem.
0:00 How to find and fix soft foot
0:06 Parallel soft foot
0:43 How to fix parallel soft foot
1:15 Bent foot
1:57 How to fix bent foot
2:14 Squishy soft foot
2:44 How to fix squishy soft foot
3:01 Induced soft foot
3:42 How to fix induced soft foot
Soft foot find-and-fix
Parallel soft foot:
The feet are not coplanar, that is rocking or parallel. The laser system shows high readings for soft foot at opposite corners. Readings from the feeler gauge determine which foot or feet to shim and how much.
Why does this happen?
One, leg is too short, or two, the base plate or mounting pads are not coplanar.
Insufficient shims under one foot or both, diagonally opposed feet.
How do you correct it?
If one foot is too short the feeler gauge shows that the short foot has an even air gap, and the opposite air gap is tapered inward. Shim the amount of even air gap under the short foot. If two feet are short: the feeler gauges show tapered air gaps that are bigger outwards on both feet. Shim both saw feet about 60 percent of the feeler gauge values.
Bent foot / outside angled foot:
The bottom of the foot is not coplanar with the base. The laser systems show high soft foot readings at three or four feet. The feeler gauge foot with the highest soft foot reading will show a tapered air gap from one corner of the foot to another.
Why does this happen?
The machinery has been dropped or otherwise roughly handled. The base plates are bent or poorly machined. There's a severe vertical angular misalignment. The feet are welded. Foundation settling has occurred.
How do you correct it?
Re-machine the feet, the base or both. Build a step shim or a metal wedge.
Safety note: Trim the excess portion of the step shims that protrude and
discard.
Squishy soft foot:
The laser system clearly and repeatedly indicates soft foot but the feeler gauges show little or no gap.
Why does this happen?
There's dirt, grease, paint, or rust between the foot and the base. The shims are bent. The shims have burrs or thread bite. There are too many shims. Don't use more than three shims per foot.
How do you correct it?
Remove any contamination under, around and on top of the foot. Replace bent or damaged shims. If you follow the proper initial alignment procedure this type of soft foot should not occur.
Induced:
The laser system shows more than one soft foot, usually on the same side or the same end of the machine. The feeler gauge finds a gap, usually parallel or nearly parallel.
Why does this happen?
External forces are affecting the machine frame, such as: Coupling or pipe stress. Overhung machines. Belts or chain loads on pulleys and gears. The flex conduit is excessively rigid. Structural bracing is attached to the machine. The jacking bolts are inadvertently left tight.
How do you correct it?
Eliminate the source of the external force. Use the laser alignment system for tracking
movement during pipe or coupling installation.
And always think of this! Re-measure and aim to have all soft foot readings within 0.05 millimeters to minimize machine frame distortion. Re-tighten all bolts to 100% torque.
#laseralignment #easylaser