# READING VERNIER DEPTH GAGES by lelettoa

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```									                             UNIT THREE          USING VERNIER, DIAL, AND DIGITAL INSTRUMENTS FOR DIRECT MEASUREMENTS                                                                                      121

Additional partial                                                          27 +       millimeters showing on the main scale
on the vernier
.36
27.36
millimeters showing on the vernier scale
vernier caliper with .02-mm
discrimination.

27 mm +
showing on
the main scale
The coincident point of the vernier scale
and the main scale occurs at the 18th
vernier division, corresponding to .36 mm

50 division vernier scale with each division equal to .02 mm

the main scale at the eighteenth vernier division. Since each
vernier scale spacing is equal to .02 mm, the reading on the
vernier scale is equal to 18 times .02, or .36 mm. Therefore,
.36 mm must be added to the amount showing on the main
scale to obtain the final reading. The result is equal to
27 mm + .36 mm, or 27.36 mm.

These measuring tools are designed to measure the depth of
holes, recesses, steps, and slots. Basic parts of a vernier depth
gage include the base or anvil with the vernier scale and the
fine-adjustment screw (Figure C-87). Also shown is the
graduated beam or bar that contains the true scale. To make
accurate measurements, the reference surface must be flat
and free from nicks and burrs. The base should be held firm-
ly against the reference surface while the beam is brought in
contact with the surface being measured. The measuring
pressure should approximately equal the pressure exerted
when making a light dot on a piece of paper with a pencil.                                                              Base clamp                                                    Vernier scale
On a vernier depth gage, dimensions are read in the same
manner as on a vernier caliper.

CALIPERS
Determine the dimensions in the vernier caliper illustrations
Beam
in Figures C-88a and C-88b.

SELF-TEST: READING METRIC VERNIER                                                                           Figure C-87 Vernier depth gage with .001-in.
CALIPERS                                                                                                    discrimination.
Determine the metric vernier caliper dimensions illustrated
in Figures C-89a and C-89b.
MECHANICAL DIAL INSTRUMENTS
FOR DIRECT MEASUREMENT