only approximate levelness aboard ship. The test bar
LAST. As with any shop equipment you must
method is the most accurate for shipboard use.
observe all posted safety precautions. Review your
equipment operators manual for safety precautions
The leveling of lathes actually refers to the
and any chapters of Navy Occupational Safety and
removal of the twist in the bed. This twist results
Health (NAVOSH) Program Manual for Forces
from setting the machine on an uneven foundation.
Afloat, OPNAV Instruction 5100.19B, which pertain
The machine is leveled by adjusting one or more legs
to the equipment you will be operating.
to remove the twist in the bed so that it is straight and
parallel with the spindle.
ALIGNING AND LEVELING
The Spirit Level Method
Alignment and levelness must be correct to
ensure proper operation of all engine lathes. They
must be aligned and leveled when installed and must
The leveling, or untwisting, of a lathe requires the
be checked periodically. Since the information
use of a very accurate level. An ordinary carpenter's
provided here is only a brief overview, you should
or machinist's level is not sufficiently accurate for
follow the machines' manufacturers instructions.
leveling lathes. A sensitive, graduated-tube spirit
level reading to 10 seconds of arc per graduation
The three basic methods of aligning and leveling
(0.0006 inch per foot) is required. The level should
lathes are spirit method, optical, and test bar. The
be adjustable and should have both a short base and a
optical method requires special equipment. If your
long tube.
ship or shore station has an optical shop, they may be
able to optically align your lathes or there are civilian
The procedure for leveling engine lathes is as
companies that provide this service. Since Machinery
follows:
Repairman do not optically align lathes, we will only
discuss the spirit level and test bar methods.
1. Loosen the lag screws that hold the right end
You should remember that the spirit level method
legs to the deck. Do not loosen the lag screws on the
left end (headstock) legs.
will work well at shore stations, but it will produce
Figure 6-37.--A gap lathe.
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