Proper positioning of machinery for shaft alignment requires precise moves, normally within a few thousandths of an inch. Most companies nowadays use pre-cut stainless steel shims for vertical corrections. These shims are graduated in thousandths of an inch. But often, the horizontal moves, which should be just as precise as the vertical moves, are done with a sledgehammer, which is not normally graduated in thousandths of an inch!
Please don’t beat your motors! Moving a motor with a hammer can cause all kinds of problems:
- You can get hurt.
- You can damage the motor bearings.
- You can break off cooling fins.
- You can deform the motor feet.
- It can make the laser tool or dial indicators jump around, causing errors.
- And it certainly isn’t a precision way to move machinery. You will usually move the motor back and forth many times, before you “get lucky” and land it in the right place.
There are better ways.
Jacking bolts can greatly improve the accuracy and precision of horizontal machinery positioning. They can be fabricated in house, ordered as part of the pump package, or purchased from aftermarket companies. Even bar or pipe clamps can be used as temporary jacking bolts.
Here’s an example. Let’s say you weld ¾-10 nuts onto the baseplate, and use the matching bolts as jacking bolts. The “10” in ¾-10 stands for 10 threads per inch. That means in one full rotation of the bolt, it will move 0.100”. There are 6 “flats” on the bolt head. So, rotating the bolt one flat will move the bolt 0.0166”. Knowing this will allow for a much more controlled, precise movement of the motor.
Even a hydraulic jack will allow a more controlled movement of the motor than a big hammer.
If you MUST use a hammer, use a dead blow hammer if possible. If that’s still too much to ask, please do not hit the motor directly. Use a brass bar, a block of wood, or something placed between the motor and the hammer. And never hit the motor on the end bell, or side of the motor. Strike at the feet of the motor.
