Standard Metric Micrometer - Polaris 1999 Sportsman 400 Service Manual

GENERAL INFORMATION
19
®
Anvil
STANDARD METRIC MICROMETER
Locknut Sleeve line Thimble
Sleeve marks
4 . Add ing the m icrom eter read ing s in S teps
I.
2
and 3 gives the
actual measurement,
V ernier inch micrometer
A vernier micrometer can acc urately meas ure in
ten -tho usa ndths ofan inc h (0 .00 01 in.). W hi le it has
the same markings as the standard inch micrometer.
a ve rnie r scale sc ribe d on the s leeve
(Figure 25)
makes
it
unique. The vernier scale consists of
eleven eq ually space d I
ines
marked 0-9 w ith a 0 on
each end . Th ese lines run para lle l on the to p of th e
sleeve where each line is eq ua l to 0.0001 inch.
Thus. the vern ier scale divides a thousandth of
3 11
inch (0 .001 in.) into ten-thousandths of an inch
(0.000 1 in.).
To read the vernier micrometer,
perform
the fol-
low ing steps and refer to the ex ample in Fjuure 26 :
I.
Read the micrometer in the same way as on the
standard inch micrometer. This is the initial reading.
2. If a th imb le ma rk lines up exactly w ith th e sleeve
line. reading the vernier scale is not necessary. Ifa
thimble mark does not line exactly with the sleeve
line. read the vernier scale in Step 3.
3. Read the
vernier
scale
to
find which vernier
mark lines up with the one thimble mark. The num-
ber of that
vernier
mark is the number of
ten-t hou sa ndt hs of an inch to add to the in itia l read-
ing taken in Step I.
Metric micrometer
TIle metric micrometer is very similarto the stan-
dard inch micrometer. The differences are the grad-
uations on the thimble and sleeve
as shown in
Figure 27 .
The standard metric micrometer is accurate to
o ne one-h und red th o f an millimeter (0 .0 I mm ). On
the metric micrometer. the spindle screw is ground
wi th
a
threa d pi tch o f on e-ha lf milli m eter (0.5 mm).
Thus, eve ry tum of the
thimble
w ill move the spin-
dle 0.5
111111 .
Th e sleeve line is gra dua ted in millim eters and
hal f mill imeter s.
The marks on the upper side
of the
sleeve
line
arc
equal
to 1.00
mru .
Every
fif th
mark
above the sleeve line is marked with a number. The
actual numbers depend on the size of the microme-
ter. For example, on a 0-25 mm micrometer. the
sleev e ma rks are numbered 0, 5, 10,15.20 and 25 .
On a 25-50
nun
micrometer. the sleeve marks are
numbered 25 , 30, 35, 40 , 45 and 50 . Th is numbering
sequence continues with larger micrometers (50-75
and
75- IO O ).
Each mark o n the low er side of the
sleeve line is equal to 0.5 mm.