This document discusses various measuring and testing tools used to determine lengths and angles. It describes steel rules, pocket rules, folding rules, calipers including outside, inside, and odd leg calipers. Vernier calipers are explained in detail including their parts, uses for measuring outside diameter, inside diameter, and depth. Accuracy of vernier calipers ranges from 0.1mm to 0.02mm depending on the scale. The document provides instructions for correctly reading vernier calipers.
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Measuring and testing tools
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MEASURING AND TESTING
TOOLS
Measuring tools are instruments used to determine lengths and angles.
List of Measurement and testing tools
Steel rule
Pocket (flexible) rule
Folding rule
Calipers
Outside
Inside
Odd leg
Vernier caliper
Micrometer
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Steel rule
It is used for taking small measurement (mostly below 300 mm)
One side is marked in millimeters and the other side is marked
in inches
It can also serve as a straight edge for marking out
Note: when taking measurement hold the edge so that the
divisions are in contact with the object you are measuring.
Pocket (flexible) rule
They are made of flexible steel, which are spring loaded in the
case.
They can be used to measure longer lengths up to 5 m
It is very convenient and measures both straight lengths and
curves
They can be conveniently carried in the pocket
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Folding rule
It is used for measuring lengths up to 1 m
It is made of wood or plastic
Can show both metric and imperial units
Calipers
Calipers are used to transfer to transfer measurements and
parallel lines.
The three types of calipers are outside, inside, and odd leg
(hermaphrodite)
outside inside Odd leg
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Outside caliper
It is used to check outside diameter of round bars, the
thickness of plates and for testing parallel surfaces
Inside caliper
It is used for
measuring inside diameters of holes
testing distance between shoulders
testing the sides of holes for parallelism
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Odd leg caliper
It has one caliper-like leg and
one needle-like point.
The odd leg caliper is used
to;
A. Locate outside and inside
centers by scribing three or
four arcs
B. Mark parallel line on flat or
round material
vernier caliper
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Reading (0.05)vernier scale
1. The last numbered division on the bar to the left of the zero on
the vernier scale represents the number of millimeters. In the
example above the #1 (10 mm) is the last number left of the
zero on the vernier scale.
2. Count the graduations between the last number (#1) and the
zero on the vernier scale. In the example above there are 7 (7
mm) graduations between the #1 and the zero on the vernier
scale.
3. Locate the line on the vernier scale that aligns with a bar line.
Divide the number below the line by 10. In the example above it
is the line with #8 (8/20 = 0.4 mm).
4. The measurement in the example above is 10 mm + 7 mm + 0.6
mm = 17.4 mm
5 mm+0 mm=5mm
Reading 0.05 mm accuracy vernier caliper