TYPES AND USES - Continued
VERNIER DEPTH GAGE
The vernier depth gage consists of a graduated scale (1)
either 6 or 12 inches long. It also has a sliding head (2)
similar to the one on the vernier caliper. (See chapter 6,
Using Vernier Caliper). The sliding head is designed to
bridge holes and slots. The vernier depth gage has the
range of the rule depth gage. It does not have quite the
accuracy of a micrometer depth gage. It cannot enter
holes less than 1/4 inch in diameter. However, it will
enter a 1/32-inch slot. The vernier scale is adjustable
and may be adjusted to compensate for wear.
DIAL DEPTH GAGE
Dial depth gages are for rapidly checking depths of
holes, recesses, slots, scratches, and paint thicknesses.
It should be noted that measurements made with depth
gages should be on a longitudinal axis. The depth gage
will give direct readings on the dial in half-thousands of
an inch (0.0005 in.); press the push button down until
the measuring rod contacts the work and read the depth
on the dial.
A height gage is used in the layout of jigs and fixtures.
On a bench, it is used to check the location of holes and
surfaces. It accurately measures and marks off vertical
distances from a plane surface.
The vernier height gage is a caliper with a special base
(1) to adapt it for use on a surface plate. Height gages
are available in several sizes. Most common are the
10, 18, and 24-inch gages in English measure. The
most common metric gages are the 25 and 46-
centimeter sizes. Height gages are classified by the
dimension they will measure above the surface plate.
Like the vernier caliper (see chapter 6, Reading a
Vernier Caliper), height gages are graduated in divisions
of 0.025 inch. Its vernier scale is divided into 25 units
for reading thousandths of an inch.
A surface plate provides a true, smooth, plane surface.
It is often used as a level base for surface and height
gages from which to make accurate measurements.
Surface plates are usually made of close grained cast
iron (1), are rectangular in shape, and come in a variety
Change 1 14-3