This document presents an experiment to calibrate a micrometer. It includes: - An introduction to micrometers and their components. - The procedure which involves measuring standard slip gauges using the micrometer and recording the readings. - Formulae to calculate parameters like least count, pitch, indicated reading, and percentage error. - A sample observation table to document the experimental values. - Graphs to be drawn including a graph of percentage error vs actual reading and a graph of indicated reading vs actual reading.

1. PERSENTATION ON
OF
Bachelor of Engineering
IN
Mechanical Engineering
Submitted BY
Shubham Kumar
Submitted To
DR. Ramesh Kumar
Reg. no.-19102132039
Under The Guidance Of
DR. Ramesh Kumar
(HOD)
Department OF Mechanical Engineering
Dept:-Me(HOD)
Calibration of Micrometer

2. CALIBRATION OF MICROMETERS
2
Calibration of Micrometer, by Shubham Kumar
 Apparatus : The following are the apparatuses used in this experiment:
 1. Micrometer
 2. Slip gauges
 Aim : To calibrate the given micrometer
 Theory : A micrometer, as illustrated in
Fig beside, is one of the most common
and most popular form of measuring
instruments. It is used to measure the
linear dimensions of small objects very
accurately.

3.  Principle It utilizes a screw to provide a linear scale conversion of the
circular motion of the screw head into the linear motion of the screw.
 Terminology :
 Pitch : When a screw works in a fixed nut, the screw tip moves through
a definite distance, called the pitch, for one complete rotation. It is equal
to the distance between the two consecutive threads of a screw.
 Least count : It can be defined as the distance moved by the screw when
it is rotated through one division on the head scale. This is the smallest
distance that can be measured accurately with the instrument. It is
therefore the ratio of the rotation of the pitch of the screw to the number
of head scale divisions.
CALIBRATION OF MICROMETERS
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Calibration of Micrometer, by Shubham Kumar

4.  Errors : The possible sources of errors, which may result in
incorrect functioning of the instrument, are as follows:
 1. Lack of flatness of the anvils
 2. Lack of parallelism of anvils at some or all parts of the scale
 3. Inaccurate setting of the zero reading
 4. Inaccurate reading due to inaccurate zero position
 5. Inaccurate readings shown by the fractional divisions on the
thimble.
 Components The major components of a micrometer are as
follows: 1. Frame 2. Anvil and spindle 3. Thimble and barrel
4. Ratchet driver 5. Adjusting nut
CALIBRATION OF MICROMETERS
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Calibration of Micrometer, by Shubham Kumar

5. Procedure : The experimental procedure involves the following steps:
1. Check the micrometer for smooth running over its range.
2. Clean the anvils of the micrometer carefully.
3. Find out the least count.
4. Find out the zero error.
5. Choose standard slip gauges.
6. Note down the dimensions of the chosen slip gauges.
7. Clean the chosen slip gauge.
8. Measure the slip gauge dimension over the micrometer.
9. Note down the measured reading in a tabular form as ‘Indicated reading’.
10. Repeat steps 4–8 for at least 20 trials so that the entire range of the micrometer
is covered.
11. Calculate the error and the percentage error.
CALIBRATION OF MICROMETERS
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Calibration of Micrometer, by Shubham Kumar

6. Formulae :
 The formulae used for the calculation of some parameters are described
here.
 Least count, LC = Pitch of the screw/No. of head scale divisions = ______mm
 Pitch, P = Distance moved by the spindle/One revolution of
the thimble = ______ mm
 Indicated or micrometer reading = (Pitch scale + Coinciding head scale
reading) × LC
 Error = Indicated reading − Actual reading Percentage error =
(Error/Actual reading) × 100
CALIBRATION OF MICROMETERS
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Calibration of Micrometer, by Shubham Kumar

7.  Tabular Column The experimental values can be documented in
the format given in Table below.
 Table : Observation table for the calibration of a micrometer
Observation table for the calibration of a micrometer
CALIBRATION OF MICROMETERS
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Calibration of Micrometer, by Shubham Kumar

8.  In this experiment, the following graphs need to be drawn:
 1. A graph of % error versus actual reading is drawn. The model graph is illustrated in
Fig. A.
 A graph of indicated reading versus actual reading is drawn, as illustrated in Fig. B
 Graphs
Fig A : Model graph of % error versus actual
reading .
Fig B : Model graph of indicated reading versus actual
reading
CALIBRATION OF MICROMETERS
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Calibration of Micrometer, by Shubham Kumar

9. CALIBRATION OF MICROMETERS
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Calibration of Micrometer, by Shubham Kumar