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1. Unit 2
INSPECTION AND GENERAL
INSTRUMENTS

2. Linear andAngular Measurements:
⚫The Linear Measurement
measurements of length,
includes
diameters,
⚫The Angular measurement includes
the measurement of angles or tapers
heights and thickness

3. Measurements:
⚫Measurement systems are mainly used
in industries for quality control.
⚫Often widely using measurements are
◦ Linear Measurement
◦ Angular measurement

4. Classification of Linear measuring instruments:
⚫A very common measurement is that of
dimensions,i.e.,length,width,height of an
object
⚫Linear measuring instruments are classified as
follows,
Low resolution devices (up to 0.25mm)
Medium resolution devices (up to 0.0025mm)
High resolution devices (less than microns)

5. Low resolution devices:
⚫Steel rule
⚫Steel rule with assistance of
◦ Calipers
◦ Dividers &
◦ Surface gauges
⚫Thickness gauges

6. Medium resolution devices:
⚫Micrometer
⚫Micrometer with assistance of
◦ Telescoping
◦ Extendable ball gauges
⚫Vernier calipers
⚫Dial indicators
⚫Microscope

7. High resolution devices:
⚫Gauge blocks
⚫Gauge block with assistance of
◦ Mechanical comparator
◦ Electronic comparator
◦ Pneumatic comparator
◦ Optical flats

8. Linear Measuring Instruments:
⚫Vernier caliper
⚫Micrometer
⚫Slip gauge or gauge blocks
⚫Optical flats
⚫Interferometer
⚫Comparators

9. VERNIER CALIPER:
⚫ Vernier calipers are available in size of 150
mm, 225 mm,900 mm and 1200 mm.
⚫ The selection of the size depends on the
measurements to be taken.
⚫ Vernier calipers are precision instruments,
and extreme care should be taken while handing
them.

10. Vernier caliper:
⚫Components ofVernier calipers are
◦ Main scale
◦ Vernier scale
◦ Fixed jaw
◦ Movable jaw
⚫T
ypes ofVernier calipers
◦ T
ypeA vernier caliper
◦ T
ype B vernier caliper
◦ T
ype C vernier caliper

11. TypeA Vernier Caliper:

12. TypeA Vernier Caliper:

13. Type BVernier Caliper:

14. Type BVernier Caliper:

15. Type C Vernier Caliper:

16. Type C Vernier Caliper:

17. Vernier caliper:
VERIER CALIPER WITH 0.02MM LEAST COUNT IS GENERLY USED
IM WORK SHOP.
In this Vernier caliper main scale division (49mm) are divided in to 50
equal part in the Vernier scale.
=1 mm
=4950 mm
i.e. 1 main scale division
(MSD)
1.Vernier scale division
(VSD)
Least count is 1mm – 4950 =150 mm
THE DIFFERENCE BETWEEN 1.MSD and 1. VSD=0.02MM

18. Example:
Main scale reading (MSR) =35mm
The vernier division coinciding with the main scale in the 20th
division.
Vernier scale reading (VSR)=20 X 0.02=0.40mm.
True Dimension/Value = 35mm+0.40= 35.40mm
35.40 mm

19. Vernier Depth Gauge:
 A vernier depth is very commonly used
precision instrument for measuring depth of
holes recesses,slot and step.
 Its construction and method of reading are
similar to those of a vernier caliper.

20. VERNIER DEPTH GAUGE:
 Base
 Graduated beam
 Clamping screw
 Fine adjustment mechanism
 Vernier scale

21. VERNIER DEPTH GAUGE

22. Errors in depth measurement
Base is Lifted when measured point is slided with pressure
Point pressure causes the base a triffle
Gauge is imperceptible

23. VERNIER HEIGHT GAUGE:
.
The main parts of a vernier
height gauge and their
function are given
 Base
 Beam
 Vernier slide
 Fine setting device
 Vernier plate
 Locking screws
 Scriber

24. VERNIER HEIGHT GAUGE

25. MICRO METER :
A micro meter is a precision instrument
used to measure a job, generally within an
accuracy of 0.01mm.
take
used to
are know
the outside
as outside
Micrometer
measurements
micrometer.

26. PARTS OF MICROMETER:
1. Frame
2. Anvil and spindle
3. Screwed spindle
4. Graduated sleeve or barrel
5. Ratchet or friction stop
6. Spindle clamp

27. Inside Micrometer:

28. Stick Micrometer:

29. Micrometer Depth Gauge:

30. Thread Micrometer:

31. V-Anvil Micrometer:

32. Reading the MICRO METER :

33. Reading the MICRO METER : contd.,

34. Bore gauge
Most bore gauges consist of a dial
indicator, extension pieces, bezel and
locknut, spring-loaded guide, and sensor
button

35. Measuring a bore with a bore gauge
.
practice is to check the
bore gauge in the standard
after you take each set of
measurements
to ensure that readings
are accurate

38. Gauge blocks – Use and precautions

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• Production gauges are of various types, but there is
a little doubt that the majority are in the form of
limit gauges.
• These are designed to cover a very wide range of
work.
• The general form of limit gauges is of the fixed type.
That is to say, gauging contact elements remain fixed
during the gauging process.
• Gauging elements, however, may be provided with
means for size adjustment
Classification of Limit
Gauges

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Following gauges are the most commonly used
in production work. The classification is
principally according to the shape or purpose
for which each is used.
1. Snap gauges 5. Form Comparison Gauge
6. Thickness Gauges
7. Indicating Gauges
8. Pneumatic Gauges
2. Plug gauges
3. Ring gauges
4. Length gauge
Classification of Limit Gauges
(cont..)

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9. Electric Gauges
10. Electronic Gauges
11. Projecting Gauges
12. Multiple Dimension Gauges
Classification of Limit Gauges
(cont..)

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1. Snap Gauges:
a. A Snap gauge is used in the measurement of
external dimensions,
b. It consist of a U-shaped frame having jaws
equipped with suitable gauging surfaces.
c. A plan gauge has two parallel jaws or anvils
which are made to some standard size & cannot
be adjusted
d. They may be either single-or double -ended
Description of some commonly used gauges:

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1. Snap Gauges: (Cont..)
e. Special forgings & stampings are
available commercially for their
manufacture, or they may be constructed
from gauge plate
f. Special snap or gap gauges may have to
be used for checking the recessed
diameters & other features
Description of some commonly used gauges: (Cont..)

46. Snap Or Gap
Gauge
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2. Plug Gauges:
◦ A plain plug gauge is an accurate cylinder used
as an internal gauge for size control of holes
◦ It is provided with a suitable handle for holding
& is made in a variety of styles
◦ These gauges may be either single or double
ended
◦ Double ended plain gauges have “GO” and “NOT
GO” members assembled on opposite ends,
where as Progressive gauges have both gauging
sections combined on one side
Description of some commonly used gauges: (Cont..)

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2. Plug Gauges: (cont..)
Possible Forms of Plug Gauges:
a. Solid Type (Double ended)
b. Solid Type (Single ended)
c. Renewable-end type (Double ended)
d. Progressive Type
e. Shell form type (Double ended)
f. Shell form type (Single ended)
g. Bar end Type
h. Special Types
Description of some commonly used gauges: (Cont..)

49. Plug
Gauge
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3. Ring Gauges:
– Used to gauge outside diameters
– Used in Pairs as “Go” & “Not Go”
4. Taper Gauges:
– Taper gauges are not dimensional gauges but
rather a means of checking in terms of degrees
– Their use is a matter more of fitting rather than
measuring
Description of some commonly used gauges: (Cont..)

51. Ring, Taper Plug & Taper Hole Gauge
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5. Thickness or Feeder Gauge:
◦ It consist of a number of thin blades & is used in
checking clearances & for gauging in narrow places
6. Dial Gauge:
◦ Dial gauges or Dial Test Indicators are used for checking
flatness of surfaces & parallelism of bars & rods
◦ They are also used for testing the m/c tools
◦ They can also be used for measurement of linear
dimensions of jobs which require easy readability &
moderate precision
Description of some commonly used gauges: (Cont..)

53. Thickness
Gauge
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54. Dial
Gauge
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55. Comparators – Working and advantages
MECHANICAL COMPARATOR

56. Advantages
•Mechanical comparators are not
expensive as compared to other types of
amplifying devices.
•These types of comparators don't need
any external electricity supply.
•It has extremely high magnification.
•Its optical lever is lightweight.
•These are easily understood due to a
linear scale.

57. ELECTRICAL COMPARATOR

58. Advantages of Electrical
Comparator:
•Vibrations are reduced due to
least weight of mechanical.
•It consists of less moving parts.
•By AC supply the friction errors
are reduced.
•For measuring units the
indicating instrument can be held
at remote locations.

60. Advantages of pneumatic
comparator
It is very accurate and precise.
High magnification up to 30000:
1 is possible in a pneumatic
comparator. Since indicating
device and measuring head are
placed at different places, there
is no interference. They are self-
cleaning because a jet of air
helps in cleaning the workpiece

61. Opto-mechanical measurements using
measuring microscope
OPTICAL MICROSCOPY

63. PROFILE PROJECTOR

64. Angular measuring instruments

65. Bevel protractor

67. UNIVERSAL BEVELPROTECTOR

68. clinometer
The clinometer is a tool used by plumbers,
surveyors, miners, skiers, artillery gunners, sailors,
foresters, and chiropractors to measure angles of
elevation and to determine slopes using gravity.
Although the clinometer was invented in 1889 by
William B. Melick, it is still used today to measure
the heights of objects that are difficult or cannot
be directly measured.

70. Angle gauges

73. Level gauges are sensing and measuring devices used to monitor the
level of a fluid in a tank or other storage container. These instruments
are commonly used in industrial process applications to monitor fluid
levels in drums, tanks, pressure vessels, and other similar applications.
The gauge comprises numerous pieces, including a head, float,
measuring tape, bottom anchored bracket, guide wires, elbows,
anchors, coupler, pipe support brackets, and pipework.
Level gauges have various benefits, including tolerating high
pressure, temperature, and vibrations in difficult situations. They can
be used in conjunction with a switch or alarm in a system and are
easily read from a distance. They need minimum maintenance, may be
repaired without disrupting the system, and can be tailored for
demanding applications.
Level gauges are frequently used when a direct physical measurement
of the fluid’s level is either impossible or impractical, such as when the
fluid being measured is toxic, or the tank or vessel carrying the liquid is
sealed and under pressure.
Precision level

75. SINE BAR

77. Angle dekkor

78. Alignment telescope

84. Measurement of Gears