Page 182 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Rotating Machinery: Practical Solutions

BORE READINGS

Some machines require bore readings to be taken for the
alignment process. This could be a bore and face, a bore and rim,
or a bore and bore alignment process. Any of the three systems
mentioned above is easily handled with the methods previously
outlined. Remember, a bore reading is nothing more than an up-
side-down RIM reading. Thus all that is required is to treat every
process involving a bore reading exactly opposite of a rim reading.
The bar sag is set at 12 o’clock as a negative number, since the
indicator is mounted upside-down. Bore readings also must be
divided by two; however, their algebraic sign should not be
changed when transferring across a coupling. The remainder of
the alignment process is exactly the same as dealing with rim
readings.