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22
a.
Man
ufac
turers
usually supply a standard
gauge
with
theirmicrometers.
A
standard
is
a
steel
block,
disc or rod that
is
ground
to
on
ex-
act
size to check
the accuracy
of the rnicro
me-
tcr,
For example. a
1-2 inch micrometer
is
equ ipped with
a
I
ineh
standard gouge.
A
25-50 mm micrometer
is equipped
with
a 25
mm standard gauge.
b.
Place the
standard
gouge between the mi-
crometer's
spindle and anvil and measure
the
outside diameter or length
in
thesame manner
as
measuring
a
vehicle component.
Read
the
micrometer. If the
adjustment
is
correct,
the 0
mark on
the thimbl
e
will be aligned exactly
with
the
sleeve
line.
If the 0
marks
do
not
align,
the micrometer requires
calibration.
c.
To adjust
the micrometer. follow the manu-
facturer's
instruction
provided with
the
mi-
crometer.
Proper Care of a
l\'1icromctcr
Because
the
mi
crometer is
a
precision
instru-
ment,
it
must be
used
corre
ctly and
with
great ca
re.
When using
and storing
a
micrometer,
refer to
the
followin g:
1.
Stor e
a micrometer
in
its
box
or
in
a
protected
place where
dust.
oil.
orotherdebris
cannot come
in
contact
with
them.
Do not
store
micrometers
in
a
drawer
with
othe r
tools
nor
hang them
on
a tool
board.
2.
When storing a
0- 1 in.
(0-25 mill)
micrometer,
the
spindle
and
anvil
must
not contact
eac
h other.
If
they do,
this
may
cause
rust to form on the
contact
ends or
the spind le
will
be
damaged
by
temperature
changes.
3. Do
not clean
a
micrometer with
co
mpressed
air.
Dirt
forced
under
pressure into the
tool can cause
premature
damage.
4.
Occasio
nally lubricate
the micrometer
with
ligh twe ight o
il
to
prevent rust and
corrosion.
5. Before
using a
micrometer, check
its
accurac
y,
Refer to Microm
eter
Accuracy
Check
previously
described in
this section.
Cylinder Bore Gauge
The
cy
linder boregauge
is
a
very
specialized
pre-
cision
tool
comprising
of a dial indicator, handle
and
a
number
ofdifferent
length adapters (anvils) to
C
II A PT ER ONE
adapt
the
gauge
to different bore
sizes. The bore
gauge
is used
10
make cy
linder
bore measurements
such
as bore size, taper
and
out-of-round.
De-
pending
on
the
bore
gauge, it can sometimes
be
used
to
measure
brake
caliper and
master
cylinder
bore sizes.
In some
cases.
an outside
micrometer
must
be
used
to
calibrate
the
gauge to
a
specific
bore diameter.
Select
the
correct
length
adopter
(A,
Figure
31
)
forthe
size
of
the
bore to be measured. Zero the bore
gauge
according
to
manufacturer's
instructions,
in-
sert
the bore
gouge into
the cylinder,
carefully move
it around in the bore
to
make sure
it
is
centered and
that
the
gau
ge
foot
(8,
Figure
31) sits correctly on
the bore
surface.
This
is necessary
in
orderto
obtain
a correct
reading.
Refer
to the
manufacturer's
in-
structions
for reading the
actual
measurement ob-
tained.
S
IIl:l1I IIole Gauges
A set of
small hole
gouges, allows the measu
ring
ofa small hole, groove
or slot.
The
small
hole
gauge
is
used
for
the
smallest
measurements
and
the tele-
scoping
gauges
are used forslig
htly largermeasure-
ments.
A small hole gauge is
required
to measure
rocker
ann
bore and
brake master cy
linder bore
di-
ameters. The
telescoping gauge does not have a
scale for
direct readings.
An
outside micrometer
must be used together
with
the telescoping
gauge
to
determine the bore dimension.
Carefully
insert
the sma
ll
hole
gauge into
the
bore
of
the component
to be
measured.
Tighten the
knurled end
of the gouge
to carefull
y
expanded
the
gauge
fingers to the limit
within the
bore.
Do not
o
vertighten
the gauge.
as
it
has no
built-in
release
feature.
If tightened too much. the gauge
fingers
can
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