Lab Record
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Instrumentation Lab
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Lab Record
Experiment-1
Calibration of Pressure Gauge
Date:____________
AIM
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To study and verify the performance of Bourdon pressure gauge.
APPARATUS
Bourdon trainer, Air compressor
CIRCUIT DIAGRAM
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Scale
Bourdon tube
Pointer
Tube section
Spring
Rack
Pinion
Adjustable link age
Pivot
System pressure
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Bourdans
pressure gauge
Pressure indicator
Control valve
Air inlet from toc
Pressure Vessel
Pump
Pressure cell
BSP thread
THEORY
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Connector
Pressure Transducer is a device that converts pressure into an electrical signal through VDT. A
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common type of pressure transducer in which a measurement of displacement is used to convert
pressure to an electrical output voltage is Bourdon tube pressure sensor. The transducer utilizes a
bourdon tube as the elastic element and a Linear Variable Differential Transformer (LVDT) as
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the sensor. The bourdon tube is a C-shaped pressure vessel with a flat-oval cross section that
tends to straighten as internal pressure is applied. In the displacement type pressure transducer,
one end of the bourdon tube is fixed, while the other end is free to displace. The core of the LVDT
is attached to the free end of the bourdon tube and to small cantilever spring that maintains tension
on the ore assembly. The coil of the LVDT is attached to the housing the anchors the fixed end of
the tube.
As the pressure is applied to the bourdon tube the core of the LVDT is pulled through the coil
and an output voltage develops. The output voltage is linear function of the pressure provided the
displacement of the bourdon tube is kept small.
PROCEDURE
1.
POWER: 3 pin mains cable is provided with the instrument. Connect thw3 pins socket to the
instrument at the rear panel and to the A.C mains 230V supply.
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NOTE: Before connecting ensure the voltage is 230V and the power switch is in off position.
2.
Adjust the ZERO potentiometer on the front panel till the display reads “000”.
3.
Close the release valves fixed to the pressure vessel and apply pressure on the sensor using
the Foot air pump.
4.
The core of the LVDT moves up due to the bourdon tube movement proportional to the
pressure built inside the pressure vessel. Pressure can be built up to 2.5 Kg / cm 2 only..
5.
Release the pressure in tank by manual valve in the steps of 10 PSI/5 in I/P pressure gauge
and note down the corresponding Bourdon gauge o/p (electrical) displayed DPM.
6.
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Tabulate the readings and plot the graph between I/P pressure – O/P pressure (DMP reading).
TABULAR FORM
S. No
I/P pressure ( PSI )
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O/P pressure ( PSI )
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LVDT OUTPUT
Avg.ERROR
RESULT
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VIVA QUESTIONS
1.
What transducer? What are the different types of transducers?
Ans. __________________________________________________________________
__________________________________________________________________
2.
What precision and accuracy
Ans. __________________________________________________________________
__________________________________________________________________
3.
What is range of pressure gauge?
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__________________________________________________________________
4.
What is the span of the instrument?
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5.
What is the difference between zero error and span error?
Ans. __________________________________________________________________
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Experiment-2
Calibration of Thermocouple for Temperature Measurement
Date:____________
AIM
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To measure temperature using thermocouple
APPARATUS
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TOP PANEL
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Display
: 3-1/2digit LED
2.
Inputs
: thermocouple sensor (iron constant)
3.
Zero pot
: provided for zero adjustment
4.
Span pot
: provided for calibration
5.
ON/OFF switch
: to ON/OFF the system
6.
Fuse
: 0.5 milli amps
7.
Light LED
: indicating the power supply when the instrument Is in ‘ON’ position
Range
: 0  100 0 c
RESOLUTION
: 0  10 c
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DESCRIPTION
The thermocouple is a thermoelectric device that converts thermal energy into Electric energy.
The thermocouple is used as primary transducer for measurement of temperature converting
thermocouple changes into emf.
Digital Display
Metal (1)
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Junction (2)
Junction (1)
Metal (2)
WORKING PROCEDURE
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1.
To connect the thermocouple sensor at 9 pin connector.
2.
Power ‘ON’ the switch. The front red led glow with which indicates the power available on
the instrument.
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Give the 00 c temperature to the thermocouple by keeping it into the ice, adjust the 0.000
3.
readings on the display by adjust through zero pot.
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4.
Keep the t/c into the boiling water and adjust the display reading 100.0 by adjusting through
span pot 100 0 c is calibrated.
5.
Keep the t/c in air room temperature. The indicator will display room temperature.
OBSERVATION TABLE
S. No
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Temperature in 0 c
(thermometer reading)
Display reading in 0 c
Analogue output in DC
volts
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PRECAUTIONS
1.
To get good performance from the tutor you have to maintain room temperature.
2.
To check the power source, it should be 230v +/- 10%, 50Hz. To avoid over voltage hazard.
3.
To get best performance, you have to put instrument at dust proof and humidity free environment.
4.
Do not try to open instrument or repair it. Contact manufacturer in case of any difficulty.
GRAPHS TO BE DRAWN
1.
To plot temperature Vs Analogue output
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Analogue output
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FUNCTIONAL BLOCK DIAGRAM OF DIGITAL TEMPERATURE MEASUREMENT TUTOR
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Thermocouple
Sensor
Display
Temperature sional
conditioner
Analog
Output card
Zero & Span
Network
Power supply
card
Transformer
On-off switch
Fuse Holder with fuse
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RESULT
VIVA QUESTIONS
1.
What is the principle of Thermocouple?
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Ans. __________________________________________________________________
__________________________________________________________________
2.
What is calibration?
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__________________________________________________________________
3.
How Thermocouple used for Temperature measurement and what is the range of thermocouples?
Ans. __________________________________________________________________
__________________________________________________________________
4.
What are the advantages of Thermocouple?
Ans. __________________________________________________________________
__________________________________________________________________
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Experiment-3
Calibration of Resistance Temperature Detector for
Temperature Measurement
Date:____________
AIM
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Measurement of temperature using Resistance Temperature detector.
APPARATUS
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Temperature controlled water bath.
2.
Resistance Temperature detector.
3.
Temperature Indicator and controller.
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THEORY
Platinum resistance thermometer is employed to divide the interval between the oxygen point
(297.35 F) and antimony point (1166.9F). Certain properties are desirable for RTD material. The
material has a resistivity permitting fabrication in convenient sizes without excessive bulk which
would produce poor time response. Its thermal co-efficient of resistivity is high and as constant
as possible. There by providing a linear output of reasonable magnitude. The material is corrosion
resistant and does not undergo phase changes in the temperature ranges of interest. Finally it
provides reproducible and consistent results.
Rt = Ro (1 + AT + BT2)
Rt = Resistance at Temperature T.
Ro = Resistance at 0C
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B = 6x 10-7 in unit 1 (°c) 2
T = Temperature to Be Measured In 0c
The resistance of RTD increases as the temperature increases. The resistance and
temperature are linearly related over a wide temperature range. Normally used metals for RTD
are copper and platinum. They are capable for higher accuracy than either Thermocouple or
Thermistor. The construction of RTD consists of a wire wrapped around A Solid silver core. The
total element is coated with heat conditioned coating. The RTD is enclosed in a stainless steel or
porcelain tube. Connect-the temperature transducer to the front panel of the instrument.
PROCEDURE
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Connect-the temperature transducer to the front panel of the instrument. Switch on the

power to the instrument.
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
The display reads room temperature as sensed by the sensor.

Keep the sensor in water bath and heat the water.

Note the temperature of water using the glass thermometer.

Note the temperature of water using the digital indicator.

Tabulate the readings in the tabular column and plot the graph of actual temperature vs.
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digital indicator reading.
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TABLE
Sl. No.
14
Standard
Digital
temperature using indicator
thermometer in 0 c reading in 0c
Thermo meter Resistance
reading in 0 c
in ohms
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Possible Graphs
1.
Thermometer reading Vs digital Indicator reading.
2.
Digital temperature reading Vs resistance
Observation
It is observed that the RTD exhibits good linearity in change of resistance over a wide temperature
range.
Panel Details
DISPLAY
: 3 ½ Digit LED Display of 200 mV FSD.
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INITIAL SET : Single turn potentiometer to set Initial Temperature (Room Temperature)
FINAL TEST : Single turn potentiometer to calibrate the instrument (Max. Temperature)
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SELECT
: 3Way rotary switch to select RTD, Thermocouple and Thermister.
POWER ON
: Rocker switch to control power supply to the instrument.
Connection Details
POWER
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: 3 pin mains cable is provided with the instrument. Connect the 3 pin socket to
the instrument at the rear panel and to the AC mains 230v supply.
NOTE
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in off position)
SENSORS
panel.
: Before connecting ensure the voltage is 230 V and the Power switch is
: Connect RTD, Thermistor and Thermocouple to the Connector on the rear
RESULT
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VIVA QUESTIONS
1.
What is the principle of RTD?
Ans. __________________________________________________________________
__________________________________________________________________
2.
What is calibration?
Ans. __________________________________________________________________
__________________________________________________________________
3.
How RTD used for Temperature measurement?
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__________________________________________________________________
4.
What are the advantages RTD?
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Ans. __________________________________________________________________
__________________________________________________________________
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What is the replacement for temperature measurement if RTD is not there?
Ans. __________________________________________________________________
__________________________________________________________________
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Experiment-4
Linear Variable Differntial Transformer (LVDT)
Date:____________
AIM
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To measure Displacement using Linear variable Differential Transformer.
APPARATUS
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LVDT, instrumentation Tutor
THEORY
Differential Transformers, based on a variable Inductance principle, are also used to measure
displacement. The most popular variable-inductance transducer for linear displacement measurement is the linear variable Differential Transformer (LVDT). LVDT is a widely used transducer
for conversion of mechanical displacement into proportional electric voltage. The displacement
ranges from a few microns to few tens of inches. LVDT is free temperature effects and it
provides an AC voltage output proportional to the displacement. The LVDT illustrated in the
figure, consists of three symmetrically spaced coils wound on to an illustrated bobbin. A magnetic
core, which move through the bobbin without contact, provides a path for magnetic flux linkage
between coils. The position of the magnetic core controls the manual between the center or
primary coil and with the outside or secondary coils.
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Metrology & Instrumentation
Output Voltage
0.6
0.4
0.3
0.2
Current Position
Total Linear range
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MAGNITUDE OF THE VOLTAGE OUTPUT AS A FUNCTIONAL OF LVDT CORE
POSITION
Sec.Coil 1
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Primary Coil
Core
Sec.Coil 2
Figure: Diagram to show schematically the working of LVDT
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MOUNTINGS OF LVDT ON THE CALIBRATION JIG
LVDT has to be mounted perfectly on the calibration jig. Micrometer should be moved till the
micrometer reads 20 mm. LVDT should be mounted to the center plate by the two nuts provided.
The core of the LVDT should be aligned with the core of the micrometer. Adjust the core of the
LVDT till it touches the micrometer core and tighten the nut.
6 core shielded cable
LVDT core
LVDT +/-10mm
Base plate
20
Micrometer core
Micrometer
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OPERATING PROCEDURE
1.
Connect the power supply chord at the rear panel to the 230v 50Hz supply. Switch on the
instrument by pressing down the toggle switch. The display glows to indicate the instrument
is ON.
2.
Allow the instrument in ON position for 10 minutes for initial warm up.
3.
Rotate the micrometer till it reads “20.”.
4.
Rotate the core of the micrometer till the micrometer reads “10.0” and adjust the ZERO
potentiometer till the display reads “0.00”.
5.
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Rotate back the micrometer core up to 20.0 and adjust once again CAL potentiometer till the
display reads 10.0. Now the instrument is calibrated for +/- 10.0 mm range. As the core of
the LVDT moves, the display reads the displacement in mm.
6.
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Rotate the core of the micrometer insteps of 1 or 2 mm and tabulate the readings. The
micrometer will show the exact displacement given to the LVDT core the display will read
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the displacement sensed by the LVDT. Tabulate the readings and plot the graph Actual vs
Indicator readings.
OBSERVATION TABLE
S. No
Actual Micrometer
Indicator readings
readings (mm)
(LVDT) (mm)
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Error
% Error
FORMULAE
Error = Indicator reading (LVDT) – Actual Micrometer reading
% Error = [(LVDT reading – Actual Micrometer reading)/ Actual Micrometer reading]*100
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Sample Calculations
Error = Measured value – True value
% Error = [(measured value – True value) / True value]*100
Graph:
Graph is plotted between Actual Micrometer reading on X-axis vs Indicator reading (LVDT) on
Y-axis.
Indicator readings
(LVDT)
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Actual Micrometer
readings
Figure-1: Actual Micrometer Vs Indictor readings
PRECAUTIONS
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LVDT must be calibrated for ‘MAX’ and ‘Min’ displacement accurately.
2.
Connections must be properly given by differentiating among the primary and secondary
coils.
RESULT
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VIVA QUESTIONS
1.
What is the principle of working of LVDT?
Ans. __________________________________________________________________
__________________________________________________________________
2.
What is calibration?
Ans. __________________________________________________________________
__________________________________________________________________
3.
How LVDT used for displacement measurement?
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__________________________________________________________________
4.
What are the advantages of LVDT?
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Ans. __________________________________________________________________
__________________________________________________________________
5.
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What is the replacement for displacement measurement if LVDT is not there?
Ans. __________________________________________________________________
__________________________________________________________________
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Experiment-5
Load Measurement Using Load Cell
Date:____________
AIM
To find the value of load using load cell.
APPARATUS
TOP PANEL
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1.
Display
: 3  1 digit LED
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Inputs
: Load cell
3.
Cal check
: On pushing the red switch you will observe the adjusted calibration on
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the display.
4.
Zero pot
: Provided for zero adjustment.
5.
Span pot
: Provided for calibration
6.
ON/OFF switch
: YO ON/OFF the system.
7.
Fuse
: .0.5 milli amps
8.
Light LED
: Indicating the power supply when the instrument is in ‘ON’ Position
Range
: 0-6 kgs.
Resolution
: 0.1 kg
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DESCRIPTION
The load transducer employ foil type strain gauges bonded to the load sensitive diaphragm. The
transducer is a single body piece machined from special steel, treated for maximum stability. The
design ensures high inherent linearity whilst maintaining low hysterics and ultimate safety factors.
The design uses a full bridge strain gauge configuration. These transducers are well suited for
static as well as dynamic load measurement.
Load
Digital Display
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Figure-2: Load measurement unit cell
WORKING PROCEDURE
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1.
To connect the Load cell at the 9 pin connector.
2.
Power ‘ON’ the switch. The front RED LED glow with which indicates the power available
on the instrument.
3.
Give some time to stabilize the instrument for stabilization (warming up time).
4.
Balance the load cell through the corresponding “ZERO” ten turn trim pot.
5.
Set the gain of Load Cell “SPAN” ten turn pot.
6.
Then to push the micro switch to ascertain the reading position of CAL.
7.
For example:
To apply the load on Load cell say 5 kg. You will observe some reading on the display say
something like 4.85 or so. Now you have to adjust this reading say 5.00by rotating the span
pot and to stop rotating with the desired 5.00 counts are visible.
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OBSERVATION TABLE
S. No
Load Applied in kgs
Digital Reading in kgs
PRECAUTIONS
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Analogue Output DC
(volts)
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1.
To get good performance from the tutor you have to maintain room temperature.
2.
To check the power source, it should be 230 V +/- 10% Hz. To avoid over voltage hazard.
3.
To get best performance, you have to put the instrument at dust proof and humidity free
environment.
4.
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GRAPHS TO BE DRAWN
1.
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Do not try to open instrument or repair it. Contact manufacturer in case of any difficulty.
To plot load vs Analogue output.
Output
Load
RESULT
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VIVA QUESTIONS
1.
What is load cell?
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Ans. __________________________________________________________________
__________________________________________________________________
2.
Where is load cell applicable?
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__________________________________________________________________
3.
Explain the principle of load cell?
Ans. __________________________________________________________________
__________________________________________________________________
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Experiment-6
Angular Measurement Using Angular Sensor
Date:____________
AIM
To measure angle from0 to 180 using angular sensor.
APPARATUS
TOP PANEL
: 3 1
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1.
Display
2.
Inputs
: Angular sensor
3.
Zero Pot
: Provided for zero adjustment
4.
Span Pot
: Provided for calibration
5.
ON/OFF
: To ON/OFF the system
6.
Fuse
: 0.5 milli amps
7.
Light LED
: Indicating is in ‘ON’ Position.
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digit LED
THEORY
Unique capacitance trainer module is the best trainer to demonstrate the use of capacitance as a
transducer. Two plays A1, one is fixed and another one is moving over the fixed plate parallel with
the fixed plate and parallel with the small gap between two. The over taping of the plate will act
as a capacitor with the air as a dielectric media. The parallel plate capacitor is used as a displace33
Metrology & Instrumentation
ment sensor for moving plate will displace angular to the fixed plate,but the fixed plate and moving
plates are parallel to each other. When the moving plate will move or displaced angularly displacement will show the reading or digital mode.
DIAGRAM
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2
1
1. Digital display meter
2. Light LED
3. Angular indication board
4. Fixed plates
4
5 5. Angular sensor
6
6. Moving plate
Range
: 0  180 0
Resolution
: 10
DESCRIPTION
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The tutor used is for measurement of angle through angular transducer.The change in angle will
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be given as input to the system. This will be taken as input to the system. This will be taken as
signal and converted into appropriate output signal using angular transducer.
WORKING PROCEDURE
1.
To connect the angular sensor at the 9 pin connector.
2.
Power ‘ON’ the switch. The front RED LED glow with which indicates the power available
on the instrument.
3.
Adjust the zero reading on the display by zero control trim point.
4.
Travel 20 mm through micrometer.
5.
Pull the angular sensor from zero to three sixty degrees.
6.
Adjust the span range by span control trim pot reading 360 degrees.
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Lab Record
OBSERVATION TABLE
S. No
Angle (in degrees)
Digital Reading (in degrees)
PRECAUTIONS
1.
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Analogue Output in
(milli seconds)
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To get the good performance from the tutor the experiment should be done at room temperature.
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2.
To check the power source, it should be 230V +/- 10% 50Hz. To avoid over voltage hazard.
3.
To get best performance, the instrument should be kept at dust proof and humidity free
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GRAPHS TO BE DRAWN
To plot Angle vs Analogue output
RESULT
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Metrology & Instrumentation
VIVA QUESTIONS
1.
What is angular sensor?
Ans. __________________________________________________________________
__________________________________________________________________
2.
Explain working of angular sensor.
Ans. __________________________________________________________________
__________________________________________________________________
3.
What are the different types of angular sensors?
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Ans. __________________________________________________________________
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4.
What are the applications of angular sensor?
Ans. __________________________________________________________________
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Experiment-7
Speed Measurement Using Photo Electric Sensor
Date:____________
AIM
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To measure speed using photo electric sensor.
THEORY
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This consists of a circular disc which is connected to the motor. The disc has an intermittent
reflecting (white) and non-reflecting (black) surface. When the light hits the reflecting surface on
the rotating disc, light pulses are obtained and reflected light is focused on to the photo electric
cell.
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CIRCUIT DIAGRAM
V+
R1
C1
X
R
R2
Light source
Disk
VC
Y
The frequency of light pulses is proportional to the disc speed.
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Metrology & Instrumentation
Range
: 750 – 1150RPM
Resolutuion
: 1 RPM
TOP PANEL
:
1.
Display
: 3  1 digit LED
2
2.
Inputs
: RPM transducer
3.
Single turnPot
: Motor speed control adjustment pot
4.
ON/OFF switch
: To ON/OFF the system
5.
Fuse
: 0.5 milli amps
6.
Light LED
: Indicates the power supply when the switch is in ‘ON’ Position.
a.
Display card supply +/- 5v
There are two terminals:
b.
Red
: +5v
Black
: Grid
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Signal conditioner card supply +/- 5v
There are two terminals:
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c.
Red
: +5v
Black
: Grid
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Sensor output to measure CRO
Red
: High
Black
: Low
Square wave in CRO
All the test points can be measured through millimetre AND/OR CRO
OBSERVATION PROCEDURE
1.
To connect the RPM (sensor) at 9 pin connector.
2.
Switch ‘ON’ the system. The RED LED on the front panel will glow. Which indicates the
power available on the instrument.
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3.
Give some time to stabilize the instrument for stabilization (warm up time)
4.
Display shows 0000 reading.
5.
Motor ‘ON’ minimum to maximum speed is 1150 rpm.
OBSERVATION TABLE
S. No
Motor Speed in RPM
PRECAUTIONS
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Time Period in (milli sec)
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To get the good performance from the tutor the experiment should be done at room temperature.
2.
To check the power source, it should be 230V +/- 10% 50Hz. To avoid over voltage hazard.
3.
To get best performance, the instrument should be kept at dust proof and humidity free
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environment.
RESULT
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VIVA QUESTIONS
1.
What are different speed measuring devices?
Ans. __________________________________________________________________
__________________________________________________________________
2.
Principle of contact type and non-contact type speed measuring device?
Ans. __________________________________________________________________
__________________________________________________________________
3.
What is the principle of photo electric sensor?
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4.
What are the applications of Stroboscope?
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5.
What are the advantages and disadvantages of Stroboscope?
Ans. __________________________________________________________________
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Experiment-8
RTD Measurement Tutor Using RTD Sensors
Date:____________
AIM
To measure temperature using RTD.
THEORY
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The principle of operation of resistance temperature detector (RTD) is based on the fact that
electrical resistance of many metals increases almost directly with temperature and is reproducible to high degree of accuracy. The term used to express this characteristic is well known tem-
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perature coefficient of resistance   and is defined by the appropriate formula resistance at
t 0 c Rt  Ro 1  At  .
where
R is the resistance of element at 00 c
T is temperature of the element in 0 c
 is temperature coefficient of resistance for the metal used
Generally platinum, nickel and copper are used as basic materials for RTD.
We may note the following are regards the RTD as transducer for temperature measurement.
1.
The resistance of R.T.D. increases as the temperature increases. The resistance and temperature are linearly related over wide temperature range.
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Metrology & Instrumentation
2.
In general, resistance thermometers are larger and less convenient to apply than the thermocouple. They massive and hence exhibit response characteristics.
Range
: 0  100 0 C
Resolution
: 0 .10 C
CONTROL POTS

0 0 C (Ice point) adjusted by zero pot.

100 0 C (boiling point) adjusted by span pot.
TOP PANEL
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1.
Display
: 3 1/2 digit LED
2.
Inputs
: RTD sensor
3.
Zero pot
: Provided for zero adjustment
4.
Span pot
: Provided for calibration
5.
ON/OFF switch
: To ON/OFF the system
6.
Fuse
: 0.5 milli amps
7.
Light LED
: Indicating the power supply when the instrument is in ‘ON’ position
8.
Test point
:
a)
Display card supply +/- 5V
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There are three terminals:
Red
:
Green :
+5V
Common
Black : -5V
b)
RTD Signal conditioner card supply +/-12V
There are three terminals:
Red
:
Green :
+12V
Common
Black : -12V
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c)
d)
Analogue output 2V full range
Red
: +VE
Black
: -VE
RTD sensor input point
When the system is in OFF position you can measure the resistance of RTD.
All the test point can be measured through multimeter AND/OR CRO
OPERATIION PROCEDURE
1.
To connect the RTD (sensor) at the 9 pin connector.
2.
Switch 'ON' the system the power indicator. The RED LED on the font panel will glow.
3.
Give the OOC temperature to the RTD by keeping it into the ice, adjust the 0.00 reading on
the display by adjust through zero pot.
4.
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Keep the RTD into the boiling water and adjust the display reading 100.0 by adjusting through
span pot 100.00C is calibrated.
5.
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Keep the RTD in air in room temperature. The indicator will display room temperature.
OBSERVATION TABLE
S. No.
Temperature in OC
(Thermometer Reading)
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RTD display reading in OC
Analogue output
(in DC volts)
PRECAUTIONS
1.
To get the good performance from the Tutor you have to maintain room temperature.
2.
To check the power source, it should be 230V +/- 10%, 50 Hz to avoid over voltage hazards.
3.
Handle RTD with carefully because it is very costly.
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GRAPH
1.
Plot graph temperature Vs Analogue output.
Thermometer reading
Rg
R1
RTD sensor
R2
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CAL
R3
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+Sv Power
supply
-Sv
Figure-3: Resistance Temperature Detector
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RESULT
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Lab Record
VIVA QUESTIONS
1.
What is the principle of RTD?
Ans. __________________________________________________________________
__________________________________________________________________
2.
What is calibration?
Ans. __________________________________________________________________
__________________________________________________________________
3.
How RTD used for Temperature measurement?
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Ans. __________________________________________________________________
__________________________________________________________________
4.
What are the advantages RTD?
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__________________________________________________________________
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What is the replacement for temperature measurement if RTD is not there?
Ans. __________________________________________________________________
__________________________________________________________________
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Experiment-9
Level Measurement (Capacitive Transducer)
Date:____________
AIM
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To measure the liquid level of an open tank using capacitive type Level sensor.
THEORY
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A simple capacitor consists of two electrode plates separated by a small thickness of an insulator
(solid, liquid, gas or vacuum) called the di electric. The change in liquid level causes a variation in
the dielectric between two plates, which turn causes a corresponding change in the value of the
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capacitance of the condenser.
Capacitance C = EoErA (n-1)/t
The magnitude of the capacitance depends on the nature of the dielectric constant (Eo),
varies directly with the overlapping area (A) of plates and inversely with distance between plates
(t). In parallel plate capacitor the capacitance is dependent only on dielectric constant. Capacitance varies directly with dielectric constant, which in turn varies directly. with liquid level between plates. Capacitance would be at minimum when the dielectric medium is air and at maximum when dielectric medium is liquid.
APPARATUS
1.
Level measurement trainer kit.
2.
Level sensor capacitive type.
3.
Graduated open tank.
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Metrology & Instrumentation
OPERATIONAL PROCEDURE
1.
Put the electrode assembly in container. Connect the electrode to the control unit. Connect
by patch cord probe 1 and 2 to change pump at C x .
2.
Make power on the unit.
3.
Add water up to say 25 cm in container, and wait for a moment to settle the system at fixed
value. Adjust gain adjust pot to get reading on display.
4.
Slowly drain the water up to zero level in container and adjust zero pot to get zero reading on
display.
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5.
Repeat the steps 3 and 4 to get optimum setting of both zero and gain adjust pot.
6.
Now slowly add water insteps of 2 cm in container up to 25 cm and note the display reading.
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Also note the output voltage by using digital multi meter. Tabulate the result of table 1.
7.
Now slowly drain the container insteps of 2 cm and note the display reading and output
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voltage at Vout . Tabulate the result of Table 1.
OBSERVATION TABLE
S. No
Water Level (cm)
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Display Reading (cm)
Voltage output (volt)
PRECAUTIONS
1.
To get good performance from instrument, the experiment should be done at room temperature.
2.
Insert the sensor at exact centre of the tank. Be sure it is in parallel to the tank surface.
GRAPH
1.
Plot the Graph for Water Level Vs display reading.
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Lab Record
Display
Reading
Water level reading
Level semson
Display
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Graduated operatic
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RESULT
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Tap
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Metrology & Instrumentation
VIVA QUESTIONS
1.
What is level?
Ans. __________________________________________________________________
__________________________________________________________________
2.
What is the principle operation of capacitive transducer.
Ans. __________________________________________________________________
__________________________________________________________________
3.
What are the different applications of capacitive transducers?
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Ans. __________________________________________________________________
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__________________________________________________________________
4.
What are the advantages and disadvantages of capacitive transducer.
Ans. __________________________________________________________________
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Experiment-9
Study and Calibration of a Rotameter
Date:____________
AIM
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To study and calibration of “Rotameter” for water flow measurement.
APPARATUS
Rotameter measuring setup, Measuring jar, Stop watch.
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PRINCIPLE
The variation of flow rate through an area between annual space of the tapered tube and the float
of the rotameter tube and the float generates a variable pressure drop which is related to the flow
rate.
THEORY
Rotameter is a variable area meter. In the variable area meter, the drop in pressure is constant
and the flow rate is a function of the area of the construction. A rotameter consists of a tapered
tube with the smallest diameter at the bottom. The tube contains a freely moving float, which rests
on a stop at the base of the tube. When the fluid is flowing, the float rises until its weight is
balanced buy the up thrust of the fluid. Its position then indicates the rate of flow. The area for
flow is the annulus formed between the float and the wall of the tube. The figure below shows
schematic details of rotometer tube and float. Use top edge of the float to note rotometer reading.
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Metrology & Instrumentation
PROCEDURE
1.
Connect the turbine flow sensor with indicator marked as flow sensor input.
2.
Start the set up.
3.
Adjust rotameter flow rates in steps of 1 LPM from 01 to 10 LPM and wait for few minutes
till the steady is reached.
4.
Measure the time required for collecting 1 ltr of water in measuring jar using stop watch.
5.
Drain the measuring jar.
6.
Repeat the experiment for different flow rates i.e. 1 to 10 LPM.
7.
Observe the time taken for collection of fluid with stop watch and column of fluid collected.
8.
Note the observations in the observation table.
OBSERVATION
S.
No
Rotameter
reading,fm
(L.P.M)
Time required
for 1 ltr water
collection (Sec)
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Actual
Discharge,
fa (L.P.M)
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Error =
fm-fa
(L.P.M)
Figure-4: Rotometer setup
60
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Correction
(fa-fm)
(L.P.M)
Accuracy %
={(fmfa)/fm}*100
Lab Record
CALCULATIONS
Actual discharge = [(1*60)/ Time required for 1 ltr water] LPH
Error: Rotameter reading – actual reading LPH
Percentage Accuracy : (Error/Full flow of rotameter)* 100
Specimen calculation
Considering the first observation, the specimen calculations are as follows.
Rotameter Reading fm = 1.00 L.P.M
Time required for 1 ltr water collection = 92 sec
Discharge = (1 * 60)/92 = 0.65 L.P.M
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Error = Rotameter reading – actual reading = 1.00 – 0.65 = 0.35 L.P.M
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Percentage Accuracy = | (Error/Full flow of rotameter)*100 |= | (0.35 / 10) * 100| = 3.5 %
GRAPHS
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Plot the graph of Actual discharge Vs. rotameter reading
Plot the graph of % accuracy Vs. rotameter reading.
PRECAUTIONS
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1.
All connections should be neat and clean.
2.
Rotameter has to be installed vertically.
3.
Flow has to be sent from bottom to top.
4.
Stopwatch reading has to be noted accurately.
5.
To check the power source, it should be 230V ?10%, 50 Hz. to avoid over voltage hazards.
6.
To get best performance, you have to put the instrument at dust proof and humidity free
environment.
7.
Do not try to open the instrument or repair it.
RESULT
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Metrology & Instrumentation
VIVA QUESTIONS
1.
What is principle of Rotameter?
Ans. __________________________________________________________________
__________________________________________________________________
2.
How Rotameter is to be installed?
Ans. __________________________________________________________________
__________________________________________________________________
3.
What is variable area flow meter?
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Ans. __________________________________________________________________
__________________________________________________________________
4.
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Can it be used for flow measurement of opaque fluids?
Ans. __________________________________________________________________
__________________________________________________________________
5.
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Advantages of Rotameter?
Ans. __________________________________________________________________
__________________________________________________________________
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6.
Applications of Rotameter.
Ans. __________________________________________________________________
__________________________________________________________________
7.
Name other flow measuring instruments.
Ans. __________________________________________________________________
__________________________________________________________________
8.
What is calibration?
Ans. __________________________________________________________________
__________________________________________________________________
9.
What is the relation between error and correction? table:
Ans. __________________________________________________________________
__________________________________________________________________
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Experiment-1
Measurement of Linear Dimensions by Using Vernier Calipers
and Micrometer
Date:____________
AIM
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To measure length, height, diameters of given component by using Vernier Calipers and Micrometer.
APPARATUS
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Vernier Calipers, Micrometer and work piece.
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Least Count = main scale division / no. of Vernier divisions
THEORY
Vernier calipers: Vernier calipers are employed for both internal and external measurements. It
can also be present to a given measurement for checking dimension of a component.
Principle: The principle of Vernier is that when two scales or divisions slightly different in size
are used the difference between then can be utilized to enhance the accuracy of measurement.
This consist of two rules sliding each other. Main scale is engraved on a solid L shaped frame. On
this scale the cm graduations are divided into 20 parts. So that one small division is equal to 0.05
cm one end of the frame consists of a fixed jaw shaped into a contact tip at its extremity.
The three elements of calipers are fixed beam, jaw and sliding jaw. Jaw permits substantial
improvements in the commonly used measuring techniques. The alignment of distance boundaries
with the corresponding graduations of the rule is ensure by the contact members. The datum of
67
Metrology & Instrumentation
measurement can be made to coincide precisely with one end of boundaries of distance to be
measured. The closely observable correspondence of the reference marks on the slide with the
particular scale value significantly reduces the extent of read out alignment errors.
A sliding jaw which moves along the guiding surface provided by main scale is coupled to the
vernier scale. At its extremity it contains another measuring tip. First the whole movable jaw
assembly is adjusted. The adjusting screw makes final adjustment depending upon the sense of
correct feel. The movement of adjusting screw makes the part containing lock nut to the movable
jaw. The measuring tips are so designed as to inside as well as outside dimensions.
Measuring tips (for external diamension)
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Main scale (fixed scale)
0
1
2
3
4
5
6
7
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Vernier scale (movable scale)
Clamping screw
Fixed jaw
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Movable jaw
Measuring tips (for external diamension)
LEAST COUNT OF VERNIER INSTRUMENTS
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Vernier instruments have two scales: Main scale and the Vernier scale. The main scale is fixed
and the vernier scale slides over the main scale. When zero on the main scale coincides with the
zero on the vernier scale, the vernier scale has one more division than that of the main scale with
which it coincides. So, the value of a division on vernier scale is slightly smaller than the value of
a division on the main scale. This difference is the least count.
Least count (L.C.) is the difference between the value of main scale division and vernier
scale division. Thus least count of a vernier instrument =Value of the smallest division on the main
scale - The value of the smallest division on the vernier scale. Fig. 1, illustrates the principle of
vernier scale and gives a clear idea about its least count.
The value of smallest division on the main scale is 1 mm. Fig. 1shows that 50 divisions on the
vernier scale coincides with 49 divisions on the main scale. Therefore, the value of smallest
division on vernier scale = 49/50 mm. Thus, least count = value of smallest division on main scale
- value of smallest division on vernier scale.
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Lab Record
i.e.,
L.C. = 1 – 49/50 = 0.02 mm.
The least count can also be calculated by the ratio of the value of minimum division on the
main scale to the number of divisions on the vernier scale, in this case L.C. = 1/50 = 0.02 mm.
PROCEDURE
1.
Before using the instrument, it should be checked for zero error. The zero line on the vernier
scale should coincide with zero on the main scale. If this does not happen, then error is
present in the micrometer which must be taken into account while taking the readings.
2.
The least count of the vernier is calculated.
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Least count = Minimum division on the main scale / No. of divisions on the vernier scale.
3.
Place the specimen to be measured in between the measuring jaws.
4.
Note the reading in mm on the main scale to the left of zero on sliding scale.
5.
Now count the number of divisions on the vernier scale from zero to a line, which exactly
coincides, with any line on the main scale.
6.
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Total reading can be calculated as follows.
Total reading = M.S.R. + (V.S.R X L.C)
7.
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The width and height at various sections of the work piece are measured and the average
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reading is calculated.
PRECAUTIONS
1.
Readings should be taken without parallax error.
2.
These should be not be used as a wrench or hammer because it is not rugged.
3.
They should be wiped free from dirt, chips and oil.
4.
They should be set down gently preferably in the box.
OBSERVATIONS
Main Scale Reading = M.S.R
Vernier Scale Reading = V.S.R
Least Count = L.C
Total Reading = M.S.R + (V.S.R X L.C)
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Metrology & Instrumentation
MICROMETER
It consists of an accurate screw having about 10 or 20 threads/cm and revolves in a fixed nut. The
end of the screw forms one measuring tip and the other measuring tip is constituted by a stationary anvil in the base of the frame. The spindle is advanced or retraced by turning a thimble
connected to spindle. The spindle is a slide fit over the barrel and barrel is in the fixed part
attached with the frame. The barrel is graduated in unit of 0.05 cm which is the lead of the screw
for one complete revolution. The thimble has got 25 divisions around its periphery on circular
portion. A lock nut is provided for locking a dimension by preventing motion of the spindle.
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Frame: It is so shaped as to permit measurements of diameter equal to range of micrometer and
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stiffness such that a test load of 1 kg wt. does not alter the distance between them by more than
1.5 µm. The frame is generally made of steel, cast steel, malleable cast iron or light alloy.
Ratchet Driver or Stop: The micrometer should be provided with a ratchet of friction stop
sufficiently diamond knurled to enable satisfactory operation. The torsional movement of ratchet
drive should be so regulated that force exerted between the measuring faces is 05 to .5 kgf. The
material used is suitable quality wear resistant steel.
Thimble and Barrel: All graduation lines are clearly engraved and for ease of reading the
surface of thimble and barrel should have a dull finish and are blackened.
Adjusting Nut: These are compensated for wear resistance between the screw position of the
spindle and nut. They are also provided for means of adjustment which is carried out by suitable
spanners and keys. The mean of adjustment should be such that after resetting the ports secured
and the original accuracy is not impaired.
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PROCEDURE
1.
Initially the measurement is checked for zero error.
2.
The head is rotated through a certain number of complete rotations. The distance moved by
the screw is measured from the displacement of head scale edge on pitch scale.
Pitch of screw = distance moved/ no. of rotations.
Least count
= Pitch scale/no. of dimensions on head scale.
3.
The given work piece is held between screw and fixed stud.
4.
The value of the highest division on pitch scale is taken as P.S.R.
5.
The no. of head scale divisions coinciding with index line is taken as observed scale reading.
6.
It is multiplied with least count to get the fraction of P.S.R. The fraction is added to P.S.R.
and total reading is calculated.
7.
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Micrometer readings are taken out at various sections and the average readings are calculated.
PRECAUTIONS
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1.
Readings should be taken without parallax error.
2.
Screw must be rotated by holding only knurl head provided with safety device.
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EXAMPLE OF MICROMETER READING
mm mark
20
5
15
10
0.01 mm marks on thimble
Thimble reading: 0.14 mm
Half mm mark
0.50 mm
Barrel Reading:
5.00 mm
0.00 mm
5.00 mm
Final Reading:
5.00 mm
0.14 mm
5.14 mm
Figure-1: Micrometer reading
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Metrology & Instrumentation
TABULAR FORM FOR VERNIER CALIPERS
S. No
Measuring
Parameters
Main Scale
reading 1 (in
mm)
Vernier
Coincidence (N)
2 ( in mm)
Fraction
N *L.C
3 ( in mm)
Total Reading
4 = 1+3
( in mm)
1.
2.
3.
TABULAR FORM FOR MICROMETER
S. No
Measuring
Parameters
Pitch Scale
reading 1 (in
mm)
Head Scale
coincidence (N)
2 ( in mm)
1.
2.
3.
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RESULT
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Fraction
N *L.C
3 ( in mm)
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1.
The width of given Componentis ___________________
2.
The height of given Component is ___________________
3.
The length of given Component is ___________________
4.
The thickness of given Component is _________________
Total Reading
4 = 1+3
( in mm)
VIVA QUESTIONS
1.
What is the purpose of vernier height gauge?
Ans. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
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Lab Record
2.
What is the least count of vernier height gauge?
Ans. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
3.
What are the various types of linear measuring instrument.
Ans. __________________________________________________________________
__________________________________________________________________
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__________________________________________________________________
4.
How to maintain constant pressure in micrometer?
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Ans. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
5.
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What is the purpose of adjusting nuts in a micrometer?
Ans. __________________________________________________________________
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__________________________________________________________________
__________________________________________________________________
6.
What is the range of dial bore gauge?
Ans. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
7.
What is the least count of digits verniercaliper?
Ans. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
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Metrology & Instrumentation
8.
Explain briefly about the different types of micrometres?
Ans. __________________________________________________________________
__________________________________________________________________
__________________________________________________________________
9.
What is the least count of a micrometer and how is it determined?
Ans. __________________________________________________________________
__________________________________________________________________
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Lab Record
Experiment-2
Measurement of Bores by Internal Micrometers and Dial
Bore Indicators
Date:____________
AIM
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To measure the internal diameter of a given component by using Dial indicator and Internal
Micrometer.
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APPARATUS
Dial bore indicator, cylinder block and Inside Micrometer
RANGE
Internal micrometer: 50-250 mm
Micrometer: 25 - 50 mm
Dial bore indicator: 35 - 60 mm
THEORY
The dial bore gauges are used for measuring internal diameter of a hole, which is machined. The
gauge is supplied with a set of split ball measuring contact points which are hard chrome plated to
retain original spheres along with measuring probes, setting rings are also provided to zero set
indicator wherever the probes are interchanged.
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Metrology & Instrumentation
Inside micrometer calipers has no U-shape frame and spindle. The measuring tips are constituted by the jaws with contact surfaces which are hardened and ground to a radius. One of the
jaws is held stationary at the end and second one moves by the movement of the movable jaw.
This facilities the inspection of small internal dimensions.
PROCEDURE
1.
The internal diameter of the cylinder blocks is measured.
2.
The dial gauge is set to zero.
3.
Internal diameter of the work piece is measured at the top, middle and bottom positions.
4.
Deflections obtained are added to the original diameter.
5.
Average of all readings is taken.
6.
With the help of inside micrometer the diameter is measured at different points and average
value is noted.
7.
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The measuring head is placed in contact with the surface of hole & movement of measuring
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head contact point is transmitted to the amplifying mechanism by the calibrated rods and it’s
shown on the dial indicator. These calibrated rods are located in tabular supports between
the head and dial units. The readings from dial indicator are tabulated.
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PRECAUTIONS
1.
Readings must be taken without parallax error.
2.
The gauge must be placed vertical while measuring.
Figure-2: Inside micrometer
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Figure-3: Dial bore gauge or indicator
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TABULAR FORM FOR INSIDE MICROMETER
S. No
Measuring
Parameter
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P.S.R
(mm)
H.S.R
(mm)
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H.S.R*L.C
(mm)
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P.S.R+(H.S.R * L.C)
(mm)
TABULAR FORM FOR DIAL BORE INDICATOR
S. No
Measuring Parameter
Location
(mm)
Dial indicator readings average
(mm)
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Metrology & Instrumentation
RESULT
1.
The internal diameter of given component by using inside micrometer is ————-
2.
The internal diameter of given component by using dial bore indicator is ————
VIVA QUESTIONS
1.
What is the Least Count of Vernier &outside Micrometer?
Ans. __________________________________________________________________
__________________________________________________________________
2.
What are applications of Vernier &outside Micrometer?
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Ans. __________________________________________________________________
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__________________________________________________________________
3.
What are the errors in Vernier &outside Micrometer?
Ans. __________________________________________________________________
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__________________________________________________________________
4.
Compare Vernier & Outside Micrometer.
Ans. __________________________________________________________________
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__________________________________________________________________
5.
What are the precautions required during use of inside micrometer & dial Boreindicator.
Ans. __________________________________________________________________
__________________________________________________________________
6.
Which one is more precise when compared to inside micrometer & dial boreIndicator.
Ans. __________________________________________________________________
__________________________________________________________________
7.
What are the applications of inside micrometer & dial bore indicator?
Ans. __________________________________________________________________
__________________________________________________________________
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Experiment-3
Measurement of Chordal Thickness by Using Gear Tooth
Vernier Caliper
Date:____________
AIM
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To measure the chordal thickness of gear tooth at the pitch line using gear tooth Vernier caliper.
APPARATUS
Gear tooth, Vernier gauge with caliper, outer calipers.
STANDARD MODULES
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The recommended series of modules adopted by Indian standard system are
First choice: 1,1.25,1.5,1,2,2.5,3,4,5,6,8,10,12,16 and 20.
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Second choice: 1.125,1.375,1.75,2.25,3.5,4.5,5.5,7,9,11,14 and 18.
Third choice: 3.25, 3.75,6.5
The recommended series of diametrical pitches are 20,16,12,10, 8, 7, 6, 5, 3, 21/ 2 ,11/ 4 and 1 .
THEORY
In this method gear tooth Vernier caliper is used to measure the thickness of gear tooth at the
pitch line. The gear tooth Vernier caliper consists of two perpendicular Vernier arms with Vernier
scale on each arm. One of the arms is used to measure the thickness of gear teeth and other for
measuring depth. The caliper is so set that it slides on the top of tooth of gear under test and the
lower ends of a caliper jaws touch the sides of the tooth at the pitch line. The reading on the
horizontal Vernier scale gives the value of chordal thickness (w) and the reading on the vertical
Vernier scale gives the value of chordal addendum. These measured values are then compared
with the calculated values.
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Metrology & Instrumentation
Considering one-gear teeth, the theoretical values of w and d can be found out, W is the
chord ADB, but tooth thickness is specified as an arc distance AEB also the distanced adjusted on
instrument is therefore called chordal thickness and is called chordal addendum.
W = AB = 2AD
Angle AOD =  = 360/4T
Where T is the number of teeth. W = 2AD = 2*AO sin 
i.e w = 2R sin 360/4T (R = pitch circle radius)
Module m = pitch circle diameter/number of teeth = 2R/T, therefore, R = Tm/2
And w = 2 (Tm/2) sin (360/4T)
w = chordal thickness
i.e ; w = Tm sin(90/T)
d = OC – OD
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d = chordal addendum
But OC = OE + addendum = R + m = Tm/2+m
And OD = R cos  = Tm/2 cos (90/T)
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m = module
T = No. of teeth
Therefore, d = Tm/2+m - Tm/2 cos (90/T) = Tm/2 [1+2/T- cos (90/T)]
d = m + Tm/2 [1- cos (90/T)]
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d = m(T+2)
Main Scale
Vertical Slide
Clamping Screws
Main Scale
Horizontal Side with
Vemier Scale
Figure-: Vernier gear tooth caliper
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Lab Record

C
A
E
B
h d
D

O
Figure-5: Chordal thickness method
PROCEDURE
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1.
Adjust the Vernier gear teeth caliper to zero error.
2.
Consider a gear with teeth and measure the thickness of the gear at pitch circle.
3.
Adjust the Vernier gear teeth calipers along the horizontal arm such that it is fit tightly at the
pitch circle.
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4.
Observe and note the main scale reading and Vernier scale reading of the coincident point.
5.
Now adjust the vertical arm of the calipers such that to measure the chordal addendum or
height.
6.
Tabulate the reading noted down.
PRECAUTIONS
1.
Observe the readings carefully without any parallax error.
2.
Adjust the Vernier scale at zero error.
3.
Handle the equipment carefully.
4.
Protect the instrument from rust by applying the oil.
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Metrology & Instrumentation
TABULAR FORM
S. No
Measuring
Parameters
Main scale reading
1 (in mm)
Vernier
coincidence (N)
2 (in mm)
RESULT
Fraction
N*L.C
3 (in mm)
Total reading
(4= 1+3)
(in mm)
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Tooth thickness is measured by Gear Tooth Vernier Caliper by “Chordal Thickness Method”
Theoretical value =
Practical value =
VIVA QUESTIONS
1.
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What are the applications of Gear tooth Vernier caliper?
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Ans. __________________________________________________________________
__________________________________________________________________
2.
How do we check the profile of a Gear tooth?
Ans. __________________________________________________________________
__________________________________________________________________
3.
Define various elements of a gear?
Ans. __________________________________________________________________
__________________________________________________________________
4.
What is Chordal addendum?
Ans. __________________________________________________________________
__________________________________________________________________
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Lab Record
5.
What is chordal thickness of gear tooth.
Ans. __________________________________________________________________
__________________________________________________________________
6.
What are the various parts of gear tooth Vernier? v) Differentiate gear tooth Vernier from
Ordinary Vernier?
Ans. __________________________________________________________________
__________________________________________________________________
7.
What are the different types of gears?
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Ans. __________________________________________________________________
__________________________________________________________________
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Metrology & Instrumentation
Experiment-4
Machine Tool Alignment of Test on the Lathe
Date:____________
AIM
Test for level of installation:
(a) In a longitudinal direction
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(b) In a transverse direction Measuring instruments: Spirit level, gauge block to suit the guide
ways of lathe bed, dial gauge.
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THEORY
The following are the alignment tests on the lathe machine:
LEVELLING OF THE MACHINE
Before the various tests on any machine tool are carried out, it is very essential that it should be
installed in truly horizontal and vertical planes. In horizontal plane, both longitudinal and transverse
directions are equally important. If, say, any long lathe bed is not installed truly horizontal the bed
will undergo a deflection, thereby producing a simple bend and undesirable stresses will be introduced. If the bed is not installed truly horizontal in transverse direction, twist will be introduced.
Thus the movement of the saddle can’t be in a straight line and true geometric cylinder can’t be
generated. For proper installation and maintenance of its accuracy, a special concrete foundation
of considerable depth must be prepared. Also this must be insulated from the surrounding floor by
introducing some form of damping.
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Lab Record
The level of the machine bed in longitudinal and transverse directions is generally tested by
a sensitive spirit level. The saddle is kept approximately in the centre of the bed support feet. The
spirit level is then placed at a-a (figure.1), to ensure the level in the longitudinal direction. It is then
traversed along the length of bed and readings at various places noted down. For test in transverse direction the level is placed on a bridge piece to span the front and rear guideways and then
reading is noted. It is preferable to take two readings in longitudinal and transverse directions
simultaneously so that the effect of adjustments in one direction may also be observed in the
other. The readings in transverse direction reveal anytwist or wind in the bed. It may be noted that
the two guideways may be perfectly levelled in longitudinal direction, but might not be parallel to
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each other. This is revealed by the test in transverse direction. The straightness of bed in longitudinal direction for the long beds can also be determined by other methods, e.g., using straight
edges, autocollimators or by taut wire method. But the test in transverse direction can be carried
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out only by spirit level. It is desired that the front guideway should be convex only as the cutting
forces and the weight of carriage act downward on it. If the front guideways are concave, then
the effect will be cumulative. The tendency of the carriage, under cutting forces is to lift upwards
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from the rear and this is prevented by a gib placed underneath the guideways. With the result, an
upward force acts on the rear guideways; which must, therefore, be made concave. Transverse
level may be in any direction, but no twist can be tolerated.
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Readings in Transverse
Direction
Rear Guideway
Bridge Phase
Testing and Longitudinal
Direction
Front Guideway
Figure
True Running of Locating Cylinder of Main Spindle: Locating cylinder is provided to locate
the chuck or face plate. However locating surface can’t be threaded one as threads get worn out
soon and thus introducing play in face plate or chuck. Thus locating surface is cylindrical and this
must run truly; for only then the face plate etc., can run truly. The dial indicator is fixed to the
carriage (or any other fixed member) and the feeler of the indicator touches the locating surface.
The surface is then rotated on its axis and indictor should not show any movement of needle.
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Metrology & Instrumentation
Figure
Axial Slip of Main Spindle and True Running of Shoulder Face of Spindle Nose: Let us
first distinguish between the axial play and the axial slip. Axial play means the indispensable
freedom of spindle movement in axial direction to prevent it from seizing by heating. The spindle
is supported between two bearings. Due to running of spindle, there will be a rise in temperature
and thermal expansion of spindle would be there. If no axial play is allowed, it would try to bend.
Thus there will be no adverse effect of axial play if the direction of cutting forces remains same.
If the direction of cutting force changes, there would be some error introduced due to movement
of spindle axially in either direction. Under such conditions, therefore, it is advisable to cut threads
in one direction only. Axial slip is defined as the axial spindle movement which follows the same
patternand is due to the manufacturing error. Actually this test is meant to check this error. To test
this the feeler of the dial gauge rests on the face of the locating spindle shoulder and the dial gauge
holder is clamped to the bed (figure.8). The locating cylinder is then rotated and the change in
reading noted down. The readings are taken at two diametrically opposite points. The total error
indicated by the movement of the pointer includes three main sources of errors. (i) Axial slip due
to error in bearings supporting the locating shoulder, i.e., the bearings are not perpendicular to the
axis of rotation and due to it a point on the shoulder will move axially in and out at diametrically
opposite points.(ii) Face of the locating shoulder not in a plane perpendicular to axis of rotation.
(Hi)Irregularities of front face. Due to axial slip, in screw cutting, the pitch will not be uniform due
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to periodic movement of the spindle. This, however, is not important while turning.
Figure
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Lab Record
True Running of Headstock Centre: Headstock centre is live centre and the workpiece has
to rotate with this centre. If it is not true with the axis of movement of the spindle, eccentricity will
be caused while turning a work, as the job axis would not coincide with the axis of rotation of main
spindle. For testing this error, the feeler of the dial indicator is pressed perpendicular to the taper
surface of the centre (figure. 9), and the spindle is rotated. The deviation indicated by the dial
gauge gives the trueness of the centre.
Figure
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Parallelism of the Main Spindle to Saddle Movement: This has to be checked in both vertical and horizontal planes. In this we require the use of mandrel. An important precaution in the
use of mandrels and dial indicator is mentioned here. The mandrel must be so proportioned that its
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overhang does not produce appreciable sag, or else the sag must be calculated and accounted for.
The rigidity indicator set up is also very important and must be carefully watched. Otherwise
variations in readings are recorded by pointer may be solely due to deflection of the indicator
mounting in different positions and it becomes very difficult to detect and isolate the spurious
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deflection from the true variations. If axis of the spindle is not parallel to bed in horizontal direction, a tapered surface is produced. Any deviation from parallelism of spindle axis from bed in
vertical axis will produce a hyperboloid surface. For this test, a mandrel is fitted in the taper
socket of the spindle. Mandrel has a concentric taper shank which is close fit to the spindle nose
taper. The feeler of the dial indicator is pressed on the mandrel and the carriage is moved. The
indication in horizontal plane is given by dial (b) and in vertical plane by dial (a) (figure. 10).
(a)
(b)
Figure
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Metrology & Instrumentation
True running of taper socket in main spindle: If the axis of tapered hole of the socket is not
concentric with the main spindle axis, eccentric and tapered jobs will be produced. To test it, a
mandrel is fitted into the tapered hole and readings at two extremes of the mandrel aretaken by
means of a dial indicator as shown in figure.11.
Figure
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Parallelism of tailstock guideways with the movement of carriage: Sometimes the job is
held between head-stock and tail stock centre for turning. In that case the job axis must coincide
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with the tailstock centre. If the tailstock guideways are not parallel with the carriage movement
there will be some offset of the tailstock centre and this results in taper turning. To check the
parallelism of tailstock midways in both the planes i.e., horizontal and vertical, a block is placed on
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the guideways as shown in figure.12 and the feeler of the indicator is touched on the horizontal
and vertical surfaces of the block. The dial indicator is held in the carriage and carriage is moved.
Any error is indicted by the pointer of dial indicator.
Movement of upper slide parallel with main spindle in vertical plane: The dial indicator if
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fixed in the tool post. A mandrel is fitted in the spindle. The feelerof the dial gauge is pressed
against the mandrel in vertical plane and the upper slide is moved longitudinally. This error is not
tested in horizontal plane because there is swivelling arrangement for taper turning. Parallelism of
tailstock sleeve to saddle movement. If the tailstock sleeve is not parallel to the saddle movement,
the height of dead centre would vary as varying lengths of sleeve are taken out. For the jobs held
between two centres, it is necessary that the central axis of the dead centre be coaxial with the
job axis in both the planes.
Block
Tailstock Guideways
Figure
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Lab Record
If it is not so, the jobmay be tilted up or down or in sideways due to the support of the dead
centre. The test is carried out by fixing the dial indicator on the tool post and pressing the plunger
against the sleeves first in vertical and then in horizontal plane (figure. 14). The carriage is moved
along the full length of the sleeve and deviations as indicated by dial indicator are noted down.
Tailstock sleeve should be rising towards the free end in vertical plane and should be inclined
towards the tool pressure in horizontal plane. Parallelism of tailstock sleeve taper socket to saddle
movement. A mandrel is put in the sleeve socket. The dial gauge is fixed on the tool post and
plunger ispressed against the mandrel and saddle is moved from one side to the other. This test is
carried out in both the horizontal and vertical planes.
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Figure
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Figure
Alignment of both the centres in vertical plane: Besides testing the parallelism of the axes
individually (main spindle axis and tailstock axis) it is-necessary to check the relative position of
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the axes also. Both the axes may be parallel to carriage movement but they may not be coinciding.
Figure
So when a job is fitted between the centres, the axis of the job will not be parallel to the
carriage movement. This test is to be carried out in vertical plane only. A mandrel is fitted between the two centres and dial gauge on the carriage. The feeler of the dial gauge is pressed
against the mandrel in vertical plane as shown in figure.16 and the carriage is moved and the error
noted down.
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Metrology & Instrumentation
Figure
PRECAUTIONS
1.
The mandrel must be so proportioned that its overhang does not produce appreciable sag,
else the sag must be calculated and accounted for.
2.
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The indicator set up must be rigid, otherwise variations in recordings as recorded by point
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may be solely due to deflection of the indicator.
RESULT
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VIVA QUESTIONS
1.
What is a lathe?
Ans. __________________________________________________________________
__________________________________________________________________
2.
What are principle parts of the lathe?
Ans. __________________________________________________________________
__________________________________________________________________
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Lab Record
3.
What are the types of headstock?
Ans. __________________________________________________________________
__________________________________________________________________
4.
What are the four types of tool post?
Ans. __________________________________________________________________
__________________________________________________________________
5.
In leveling of machine, which direction is more important in horizontal plane?
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Ans. __________________________________________________________________
__________________________________________________________________
6.
In what direction the parallelism of the main spindle to saddle movement is checked?
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Ans. __________________________________________________________________
__________________________________________________________________
7.
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Which of the following is done for testing the true running of headstock centre?
Ans. __________________________________________________________________
__________________________________________________________________
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Metrology & Instrumentation
Experiment-5
Angular Measurement of a given Component by using Sine
bar and Bevel Protractor
Date:____________
AIM
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To measure the angle of a given component by using sine bar and Bevel protractor.
EQUIPMENT
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Sine bar, slip gauges set, dial indicator, surface plate and Bevel protractor.
THEORY
Sine bars used in conjunction with slip gauges constitute a very good device for the precise
measurement of angles. Sine bars are used either to measure angle very accurately or for locating any work to a given angle with in very close limits. Sine bars are made from high carbon, high
chromium, corrosion resistant steel, hardened, ground and stabilized. Two cylinders of equal diameters are attached to the ends. The axes of two cylinders are mutually parallel to each other
and also parallel to and at equal distance from the upper surface of sine bar. The distance between two axes is exactly 5 or 10 inches in British system and 100, 200 and 300 mm n metric
system. All the working surfaces and the cylindrical surfaces of the rollers are finished to surface
finish of 0.2 m R a value or better. Some holes are drilled in the body of the bar to reduce the
weight and to facilitate handling.
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Lab Record
Dial Gauge
Workpiece of component
B
Sine bar
Slip
gauges H

A
C
Surface plate (Datum surface)
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Sine bar
Roll
A
Workpart to be measured
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H
Gage blocks
Figure: Sine bar
PROCEDURE
Sine bar is kept at an angle to the surface plate by keeping it on the slip gauges of the required
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height and the object is placed on the surface of the sine bar such that the top surface of object is
nearly horizontal. Now by moving the dial gauge from one end to other end the difference in
heights of the two ends of the object from the surface plate is obtained. Depending on the situation height of the slip gauges can be increased or decreased.
Sin  h / 1  h 2  h 1  / 1
h = height of slip gauges
l = distance between centres of rollers
PRECAUTIONS
1.
The plate on which sine bar is placed must be perfectly flat.
2.
Slip gauges must be properly selected.
3.
Deflection in the dial gauge must be accurately noted.
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Metrology & Instrumentation
TABULAR FORM FOR SINE BAR
S. No
Height of slip gauges ( in mm)
Total Angle (in degrees)
RESULT
The taper angle of a given component using sine bar is ——
BEVEL PROTRACTOR
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Theory: The angle is defined as the opening between two lines, which meet at a point. If a circle
is divided into 360 parts, each part is called a degree (0). Each degree is further divided into sixty
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parts called minutes (1) and each minute is further subdivided into 60 parts called seconds ( 11).
Bevel protractor is the simplest instrument for measuring the angle between two faces of a
component. It consists of a base plate attached to the main body and an adjustable blade, which is
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attached to a circular plate containing Vernier scale.
Various components of Bevel Protractor:
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Blade
Blade locking nut
Turrent
Working edge
Acute angle attachement
Locking nut
Slow motion device
Stock
Main scale
Vernier scale
Main body
Working edge
Figure: Bevel Protractor
Body: It is designed in such a way that its back is flat and there are no projections beyond its back
so that when the bevel protractor is placed on its back of its surface plate. The flatness of the
working edge of the stock and body is tested by checking the square ness of blade with respect to
stock and blade is set at 900.
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Lab Record
Stock: The working edge of the stock is about 90 mm in length and 7 mm thick. It is very essential
that working edge of the stock is perfectly straight and if at all departure is there, it should be in
the form of concavity and of the order of 0.01 maximum over the whole span.
Blade: It can be moved along the turret through out its length and can also be reversed. It is about
150 or 300 mm long, 3 mm wide and thick and ends bevelved at angles 450and 600with in the
accuracy of 5 minutes of arc. Its working edge should be straight up to 0.02 mm and parallel up to
0.03 mm over the entire length of 300 m. it can be clamped in any position.
Acute angle attachment: It can be readily fitted into the body and clamped in in any position. Its
working edge should be flat to with in 0.005 mm and parallel to the working edge. Bevel protrac-
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tors are tested for flatness, square ness, parallelism, straightness and angular intervals by suitable
methods.
PROCEDURE
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The given specimen is placed on the working edge of the base plate.
2.
Moving blade of the protractor, which is in contact with circular Vernier scale, is rotated so
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that the blade is in contact with the surface of the specimen where angle is to be determined.
3.
Then the circular blade containing the Vernier scale is fixed and the readings of the Vernier
are noted.
4.
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The procedure is repeated for different specimens.
PRECAUTIONS
1.
Angle should be measured without parallax error.
2.
Circular blade must be in contact with surface of specimen.
TABULAR FORM FOR BEVEL PROTRACTOR
S. No
Main scale reading
(degrees)
Vernier coincidence *
L.C (min)
Total Angle (in degrees)
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Metrology & Instrumentation
RESULT
The taper angle of a given component by using Bevel Protractor —————VIVA QUESTIONS
1.
Name some angle measuring devices?
Ans. __________________________________________________________________
__________________________________________________________________
2.
What is the least count of mechanical Bevel Protractor?
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Ans. __________________________________________________________________
__________________________________________________________________
3.
What is the least count of optical Bevel Protractor?
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Ans. __________________________________________________________________
__________________________________________________________________
4.
What is a sinebar?
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Ans. __________________________________________________________________
__________________________________________________________________
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5.
What are the limitations of Sinebar?
Ans. __________________________________________________________________
__________________________________________________________________
6.
What is the difference between the sine bar and sine center?
Ans. __________________________________________________________________
__________________________________________________________________
7.
What is the use of V-block?
Ans. __________________________________________________________________
__________________________________________________________________
8.
How do you specify sinebar?
Ans. __________________________________________________________________
__________________________________________________________________
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Lab Record
Experiment-6
Checking the Flatness of the Surface Plate by
using Spirit Level
Date:____________
AIM
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To check the flatness of surface plate by using spirit level.
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APPARATUS
Spirit level, Surface plate
THEORY
Spirit levels are used for measuring the small angle or inclinations and also enable the position of
a surface to be determined with respect to horizontal. A spirit level consists of a sealed glass tube,
ground on its inside surface to a convex form with a large radius of curvature. A scale is engraved
on the glass at the top of the tube. The tube is nearly filled with either such that only a small
volume remains at the top part of the tube, which contains either vapors in the form of a bubble.
The side edges of the frame level are made strictly square with the base. A glass tube filed with
either is mounted in the base. For checking the vertical surfaces, the side edge of the frame level
is placed in to exact contact with the surface and reading of the bubble noted down.
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Metrology & Instrumentation
Figure-19: Spirit level
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Figure: Spirit levelused for checking the straightness of the wall
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PROCEDURE
1.
Take a surface plate and place the spirit level on it to check flatness.
2.
The glass tube is set in the base and adjusted in such a way that when the surface is
horizontal the bubble rests at the center of the scale, which is engraved on the glass.
3.
When the base of the level is moved out of the horizontal, the bubble tries to remain at the
highest point of the tube and thus moves along the scale.
4.
To check the flatness of entire surface plate, place the spirit level at different places randomly and note down the readings.
PRECAUTIONS
1.
Readings should be taken without parallax error.
2.
Handle the equipment carefully.
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Lab Record
RESULT
VIVA QUESTIONS
1.
What is the use of Spirit Levels?
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Ans. __________________________________________________________________
__________________________________________________________________
2.
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Where the bubble rests on the scale when spirit level is placed horizontally?
Ans. __________________________________________________________________
__________________________________________________________________
3.
What is the range of base length of type-1 spirit level?
Ans. __________________________________________________________________
__________________________________________________________________
4.
For which surfaces, spirit level is used for testing straightness?
Ans. __________________________________________________________________
__________________________________________________________________
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Metrology & Instrumentation
Experiment-7
Measurement of Screw Thread Profile Using Tool
Maker’s Microscope
Date:____________
AIM
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To measure various elements of a given screw using Tool maker’s microscope.
APPARATUS
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Tool maker’s microscope, Specimen
THEORY
The tool maker’s microscope is a versatile instrument that measure by optical means with no
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pressure being involved thus very useful for measurement on small and delicate parts.
It is designed for:
a.
Measurement on parts of complex form e.g. – profile of external thread, tool, templates,
gauges, etc.
b.
Measuring centre to centre distance of holes in any plane.
c.
A variety of linear measurements.
d.
Accurate angular measurements.
SPECIFICATION
MAGNIFICATION: 30X (Standard)
OBJECTIVE: 2X
EYEPIECE: W.F.15X with crossrectile
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Lab Record
FIELD OFVIEW: 8mm. (approx.)
WORKINGDISTANCE: 80mm
OBSERVATIONTUBE: monocular inclined at 30degree
STAND: largeandheavybaseprovideextraoverallrigiditytothe instrument
MEASUREMENT STAGE: 150X150.
Size travel up to 50mm in each direction, least count 6 minutes.
CONSTRUCITON OF MICROSCOPE
BASE: The study base rest on three support two of which are adjustable for levelling the instru-
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ment. The base has built in all electrical transformers and their control panel and transmitted
illuminator with green filter.
ARM: The arm has a groove guide on which the microscope tube is vertically adjusted by rack
and pinion system
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FOCUSSING MECHANISM: The course focusing movement provided in the microscope
tube separately. The coarse motion is knurled knob on both side of the tube and ha as the total
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travel of 200mm. It’salso lock any position by lever, this movement is characterized by its exceptionally smooth and accurate precision. The vertical travel or measurement up to 10mm, thickness
can be read by the depth dial gauge. The thickness is being measured with the difference of two
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different focusing of object. The least count of gauge is 0.01.
Eye piece
Optical head
Column
Work table
with carriage
Hollow base
Lamp
Collimator lens
Mirror
Base
Figure: Tool maker’s microscope
101
Metrology & Instrumentation
EYEPIECE PROTRACTOR: This unique protractor head graduated 0 to 360 degree with
adjustable vernier reading to 6 minutes cross line incorporated in the protractor head rotating in
the optical axis of the microscope the cross linegraticules is replaceable with many other
measuringgraticules.
MEASURING STAGE: The stage plate is of 150 X 150 mm having very smooth and precise
movements in both axis with special ball racers arrangements. The travel of the stage is 25mm. In
both direction with precise imported micrometer head, least count 0.01 or 0.005mm. The stage
has two T-slots for mounting accessories like rotary stage, center holding device attachment and
V-blocketc.
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ROTARY STAGE: A rotating stage is fixed in T-slots of square plate having 360 degree graduations on its periphery with vernier reading to6 minute, and lock screw. All types of horizontal
angular measurements can be done with this stage.
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ILLUMINATING SYSTEM: Two possible range of illuminating system are provided with
standard equipment to meet every application, operated through 6 volts solid state variable light
control built in transformer.
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Sub-stage transmitted light from a bottom source providing collimated green filter halogen
light for viewing contours and transparentobjects.
2.
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Surface incident illuminator for shadow free lighting, for high power examination of opaque
objects.
PROCEDURE
MEASUREMENT OF SCREW THREAD PITCH
1.
The image of the thread profile is set so that some of the profile coincides with the cross hair
as seen on the ground-glass screen.
2.
The reading on thimble of the longitudinal micrometer screw is noteddown.
3.
Then the part is traversed by the micrometer screw until a corresponding point on the profile
of the next thread coincides with the crosshairs.
4.
The reading on thimble is again noted and the difference in two readings gives the actual
pitch of thescrew.
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Lab Record
MEASUREMENT OF ANGLE OF THREAD
1.
It is determined by rotating the screen until a line on the screen coincides with one flank of
the threadprofile
2.
The angle of screen rotation is noted and then the screen is further rotated till the same line
coincides with the other flank of thread. The difference in two angular readings gives the
actual angel of thread on thescrew.
TABULAR FORM FOR PITCH OF THE THREAD
S. No
Micrometer reading in mm
Pitch of the thread B-
Initial micrometer readings on
Final micrometer readings
thread pitch A(mm)
on thread pitch B(mm)
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A (mm)
TABULAR FORM FOR ANGLE OF THE THREAD
S. No
Initial angle in
degrees
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Final angle in
degrees
Difference
Mean
CALCULATIONS
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Metrology & Instrumentation
PRECAUTIONS
1.
Readings should be noted without parallax error.
2.
The instrument is to be cleaned for dirt and must before use.
RESULT
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Thus the elements of the given screw were measured by using Tool Maker’s Microscope.
Pitch of the screw :
Thread angle :
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VIVA QUESTIONS
1.
What are the applications of Toolmakers microscope?
Ans. __________________________________________________________________
__________________________________________________________________
2.
State the principle involved in Toolmakers microscope?
Ans. __________________________________________________________________
__________________________________________________________________
3.
How to change the magnification in Toolmakers microscope?
Ans. __________________________________________________________________
__________________________________________________________________
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Lab Record
Experiment-8
Surface Roughness Measurement with Roughness
Measuring Instrument
Date:____________
AIM
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To measure the surface roughness parameters Rz, Ra and Rmax using surface roughness tester.
APPARATUS
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Surface roughness tester and specimens
THEORY
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Surface roughness testers are used when visual and feel comparisons are just not sufficient. This
instrument is compatible with four standards of site to measure surface roughness of various
machinery-processed parts, calculate corresponding and clearly display all measurements parameters. When measuring the roughness of a surface, the sensor is placed on the surface and then
uniformly slides along the surface by driving the mechanism by the sharp built-in probe. This
roughness causes displacement of the probe which results in change of inductive amount of
induction coils so as to generate analogue signal, which is in proportion to the surface roughness
at output end of phase-sensitive rectifier.
Transducer
(pieze-electrical or inductive)
Scanning arm
105
Metrology & Instrumentation
MECHANICAL DETERMINATION OF ROUGHNESS PARAMETERS
The figure shows the principle for scanning the surface profile. The piezo-electrical transducer is
used for simpler tasks and the inductive transducer for more demanding ones.
R a  The mathematical average value for roughness Rais the generally recognized parameter
and the one mostly used internationally. The average roughness value is the mathematical average of the absolute profile deviations within the scanning path. Rais preferably used in order to
evaluate gradual surface changes.
Roughness parameter Ra
Z[x]
Z
r
t
l
m
u
Ra
X
For example, this is the case with grinding when the grinder becomes less effective. How-
c
e
ever, different profile forms cannot be detected using the Ravalue. The measured numerical
value for R a is always smaller than that of the R z valuedetermined on the same roughness
profile due to the calculation formula.
p
S
R z  The determined roughness. The determined roughness depth R z is the mathematical aver-
age from the largest individual roughness depths znfrom a number of individual measurement
paths I e   c . Average of the largest roughness depths of measurement paths directly adjacent to
each other weakens the influence of individual peaks and ridges. The complete path l is the sum
of the individual measurement paths.
z1
z2
z3
z4
z5
Ie=c
l
Roughness parameter R z 
106
z1  z 2  z 3  z 4  z 5
5
Lab Record
PROCEDURE
1.
Select the measuring range, evaluation length, and cut-off value, depending on the surface to
be measured.
2.
Choose the pick-up system that is suited for the application.
3.
Carry out a freehand measurement of the specimen surface.
4.
Generate the required surface roughness values and record the results in the format.
OBSERVATIONS
Traversing Unit:
Traversing length: ________________
Tracing speed
: ________________
Evaluation length: ________________
Specimen Number
1
2
p
S
3
4
Rz (µm)
c
e
r
t
Ra (µm)
m
u
Rmax(µm)
5
RESULT
VIA Procedure
1.
Select the measuring range, evaluation length, and cut-off value, depending on the surface to
be measured.
2.
Choose the pick-up system that is suited for the application.
3.
Carry out a freehand measurement of the specimen surface.
4.
Generate the required surface roughness values and record the results in the format.
107
Metrology & Instrumentation
OBSERVATIONS
Traversing Unit:
Traversing length: ________________
Tracing speed
: ________________
Evaluation length: ________________
VIVA QUESTIONS
1.
Define the following terms a) Roughness b) Waviness c) Lay d) Sampling Length.
m
u
Ans. __________________________________________________________________
__________________________________________________________________
2.
Explain the terms Ra,Rz, RMS.
r
t
Ans. __________________________________________________________________
__________________________________________________________________
3.
c
e
What are the various methods of measuring surface roughness?
Ans. __________________________________________________________________
__________________________________________________________________
4.
p
S
Explain the use of dial bore gauge?
Ans. __________________________________________________________________
__________________________________________________________________
5.
What is the principle involved in sprit levels?
Ans. __________________________________________________________________
__________________________________________________________________
108