Micrometers - Hisun HS400 Service Manual

Although not as precise as a
micrometer, they allow reasonable
precision, typically to within 0.05 mm
(0.001 in.). Most calipers have a range
up to 150 mm (6 in). Calipers are
available in dial, venire or digital
versions. Dial calipers have a dial
readout that provides convenient
reading. Venire calipers have marked
scales that must be compared to
determine the measurement.
The digital caliper uses a liquid-crystal
display (LCD) to show the measurement.
Properly maintain the measuring
surfaces of the caliper. There must not
be any dirt or burrs between the tool and
the object being measured. Never force
the caliper to close around an object.
Close the caliper around the highest
point so it can be removed with a slight
drag. Some calipers require calibration.
Always refer to the manufacturer's
instructions when using a new or
unfamiliar caliper. To read a Vernire
Caliper refer to Figure 21.
The fixed scale is marked in l-mm
increments. Ten individual lines on the
fixed scale equal 1 cm. The movable
scale is marked in 0.05 mm (hundredth)
increments. To obtain a reading,
establish the first number by the location
of the 0 line on the movable scale in
relation to the first line to the left on the
General
fixed scale. In this example, the number is 10
mm. To determine the next number, note
which of the lines on the movable scale align
with a mark on the fixed scale. A number of
lines will seem close, but only one will align
exactly. In this case, 0.50 mm is the reading
to add to the first number. Adding 10 mm and
0.50 mm equals a measurement of 10.50mm.

Micrometers

A micrometer is an instrument designed for
linear measurement using the decimal
divisions of the inch or meter (Figure 22).
While there are many types and styles of
micrometers, most of the procedures in this
manual call for an outside micrometer. Use
the outside micrometer to measure the
outside diameter of round parts and the
thickness of materials. A micrometer's size
indicates the minimum and maximum size of
a part that it can measure. The usual sizes
(Figure 23) are 0-25mm (0-1 in), 25-50 mm
(1-2 in), 50-75 mm (2-3 in) and 75-100 mm
(3-4 in).
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