Calibration tools
RESTRICTED
Precision
Surface
Plates
and
Tables
Precision
Level
Precision
Mirror
Tachometer
CALIBRATION TOOLS
Precision surface plates and leveling tables
provide
a true surface which
may be used as a re-
ference
and provide a precision surface upon which
the precision level may be leveled.
PRECISION LEVEL. The precision level is used
to level
the stand, stabilizer, vertical gyro and
precision
precision level consists of two parts,
capable by turret
adjustments of chang
ing their relationship to each
other.
First there
is the glass tube containing the liquid with its
bubble.
Then there
is the
The level has been properly leveled when the
base the prectecte
The procedure to accomplish this is to place
the level upon the adjustable three-legged table.
(Actually a
precision table is inserted between
the two, but it has no significance other than to
provide a perfectly flat surface). Then the thumb
screws of the adjustable table are rotated until
the bubble is centered.
Now two things are true:
the glass is perfectly horizontal and (2) in-
sofar as the base is not it has exactly the same
amount--but opposite--of error
in tas has the
adjustable table.
By positioning
the precision
level about 180°
, we find
out how much this error
is
and are
also in a position to remove one-half
of it with
the level and the other half with the
table. When the level has been turned about 180°.
the error in the level is now not only equal with
that in the table but
also they are the same and
not opposite errors.
If exactly one-half of the
error were removed
with the level and the remain-
ing one-half
with the table,
then there would
be
no need of again turning the level about 180°
The level should be checked for accuracy from
time to
by positioning it on a true surface
about 180°; if the level is accurate, the bubble
should
be
off exactly the same amount in each
case.
The precision mirror is used for the reflect-
surface to
level
erect the optics.
The mirror must
used only in
shop calibration.
Speed
mine the
indicator (tachometer) is used to deter-
revolutions per minute (rpm) of revolving
the
mirror.
The
base.
parallel
to
the
glass.
ing
be
and
is
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