Page 212 - Machinery Component Maintenance

194 Machinery Component Maintenance and Repair

we also add - .007 in. to the south rim reading, giving us - .029 in. Tak-
ing half of this, we find that the machine element to be adjusted is .0145
in. north of the stationary element at the plane of measurement.
Finally, we do a similar operation on our horizontal face readings, and
determine that the north face distance is wider by .014 in.
The remaining part of the form provides space to put the calculated
corrective movements. Although these have been filled in for our exam-
ple, let’s leave them for the time being, since we are not yet ready to
explain the calculation procedure. We will show you how to get these
numbers later. If you think you already know how, go ahead and try-the
results may be interesting.
You have now seen the general idea about data recording and interpre-
tation. By doing it systematically, on a prepared form corresponding to
the actual field setup, you can minimize errors. If you are interrupted,
you will not have to wonder what those numbers meant that you wrote
down on the back of an envelope an hour ago. We will defer consider-
ation of the remaining setups, until we have explained how to calculate
alignment corrective movements. We will then take numerical examples
for all the setups illustrated, and go through them all the way.

Calculating the Corrective Movements

Many machinists make alignment corrective movements by trial and
error. A conscientious person can easily spend two days aligning a ma-
chine this way, but by knowing how to calculate the corrections, the time
can be cut to two hours or less.
Several methods, both manual and electronic, exist for doing such cal-
culations. All, of course, are based on geometry, and some are rather
complicated and difficult to follow. For those interested in such things,
see Refercnces 1 through 15. Also, the alignment specialist should be
aware of programmable calculator solutions. These make use of popular
calculators such as the TI 59 and HP 67. By recording the alignment
measurements on a prepared form, and entering these figures in the pre-
scribed manner into the calculator, the required moves come out as an-
swers. A variation of this is the TRS 80 pocket computer which has been
programmed to do alignment calculations via successive instructions to
the user telling him what information to enter.
By far the simplest calculator is the one described earlier in conjunc-
tion with the laser-based OPTALIGN@ system. Next to it, we rank the
IMS calculator. l4 This is designed specifically “from the ground up’’ for
the more common face-and-rim and reverse-indicator calculations, rather
than being a standard commercial calculator or computer adapted for
alignment. For the more complex multi-element trains, larger central
computers can be used directly with telephone linkups. Ray Dodd’s book