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
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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Vernier caliper
Dial caliper
Digital caliper
Some of types caliper
Measuring outside diameter
Measuringinside diameter
measuring depth
Uses of a vernier caliper

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Depth
probe
Outside jaws
Inside jaws
Main scale
Screw clamp
Vernier
scale
Parts of a Vernier caliper
Correct
wrong wrong
Taking outside measurements

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correct
wrong
wrong
Measuring inside diameter
correct
wrong wrong
Measuring depth of a recess

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1/10= 0.1
1/20= 0.05
1/50= 0.02 Measurement accuracy
Vernier scales
How to read the 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

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23 mm+0.40 mm=23.40mm
Reading 0.05 accuracy vernier caliper
1 2
4
3

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1 2
4
3
11mm
23.40mm 48.85mm
5mm
Read vernier caliper with an accuracy of 0.02