Download - Calibration of Vernier Capilier
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IIT-Gandhinagar METROLOGY LAB
INDIAN INSTITUTE OF TECHNOLOGY, GANDHINGAR
CALIBRATION OF VERNIER CALIPER
METROLOGY LAB
NAME: ANIL CHEJARA
ROLL NO: 9003022
GROUP: 5
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IIT-Gandhinagar METROLOGY LAB
Table of Content:
1. Objective________________________________________________________________________3
2. Equipment______________________________________________________________________ 3
3. Theory _________________________________________________________________________3
4. Procedure_______________________________________________________________________4
5.Observation______________________________________________________________________5
5. Calculations______________________________________________________________________6
6. Conclusion_______________________________________________________________________7
7. Comment________________________________________________________________________7
SIGNATURE Prof. N. RAMAKRISHNAN IIT GANDHINAGAR
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IIT-Gandhinagar METROLOGY LAB
AIM: To calibrate vernier caplier.
EQUIPMENT: Vernier Caliper and box of slip gauges
THEORY:
Calibration is done to check precision and accuracy of the measuring instrument. If we have references
which are very accurate and well kept under control environment, they can be used to calibrate.
Slip gauge is a precision ground and lapped length measuring standard used as a reference for the
calibration of measuring equipment used in machine shops, such as micrometers, sine bars, calipers,
and dial indicators.
Vernier caliper is capable of measuring internal and external dimensions and can also be used as a depth
gauge. The Vernier Caliper is a precision instrument that can be used to measure internal and external
distances extremely accurately. The vernier, dial, and digital calipers that give a direct reading of the
distance measured to high accuracy. These calipers comprise a calibrated scale with a fixed jaw, and
another jaw, with a pointer, that slides along the scale. Its least count is 0.1 /0.2 mm
The vernier scales may include metric measurements on the lower part of the scale and inch
measurements on the upper, or vice versa, in countries that use inches. Vernier calipers commonly used in
industry provide a precision to 0.01 mm (10 micrometres), or one thousandth of an inch. They are
available in sizes that can measure up to 1,829 mm (72 in).
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IIT-Gandhinagar METROLOGY LAB
BOX OF SLIP GAUGES:
Slip gauge is a precision ground and lapped length measuring standard. They are used as a
reference for the calibration of measuring equipment used in machine shops, such
as micrometers, sine bars, callipers and dial indicators. Gauge blocks are the main means of
length standardization used by industry.
They are the most accurate standards of length available for use in workshops. The accuracy
and finish is so high that two or more slip gauges may be wrung together. When correctly
cleaned and wrung together, the individual slip gauges adhere to each other by molecular
attraction and if left like this for too long, a partial cold weld will take place. If this is allowed
to occur, the gauging surface will be irreparably after use, the gauges should be separated
carefully by sliding them apart. They should then be cleaned, smeared with oil or petroleum
jelly (Vaseline) and returned to their case.
PROCEDURE:
Check the zero error of the vernier callipers.
Take the slip gauges from the box of different sizes and measure them using the
vernier callipers.
Compare the measured value with the given value of the gauges.
After that, combination procedure, we keep two mirrored surfaces at 90 degrees and
turn so that they stick and their final length will be sum of individual lengths.
Now measure the combined length using the vernier caliper and find out the error.
Take care that the gauges are attached properly. Inability to do that would lead to errors.
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IIT-Gandhinagar METROLOGY LAB
OBSERVATIONS:
1) Using single slip gauge
Sr.No. Slip Gauge Reading (mm)
Vernier caliper Reading
(mm)
1 1.45 1.44
2 2.5 2.46
3 3.5 3.5
4 6.5 6.48
5 7 7
6 9 8.98
7 12 11.98
8 14 13.98
9 15 14.98
10 17.5 17.48
11 20 20
12 21.5 21.48
13 23 22.98
14 24.5 24.48
15 50 50
2) Using combination of slip gauges
Sr.No. Combination used Gauge Reading (mm)
Vernier caliper Reading
(mm)
1 3.5+4+5+5.5 18 17.96
2 10+15+16 41 41.04
3 10.5+23.5+24 58 57.98
4 10+50 60 59.98
5 15+23.5+24 62.5 62.6
6 3+75 78 77.98
7 50+75 125 125.08
8 9+50+75 134 134.12
9 20+24.5+100 144.5 144.5
10 50+75+150 225 225
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IIT-Gandhinagar METROLOGY LAB
CALCULATIONS:
Sr.no. Standard Reading (mm)
Vernier Reading (mm)
Error (mm)
%Error
1 1.45 1.44 0.01 0.69
2 2.5 2.46 0.04 1.6
3 3.5 3.5 0 0
4 6.5 6.48 0.02 0.308
5 7 7 0 0
6 9 8.98 0.02 0.222
7 12 11.98 0.02 0.167
8 14 13.98 0.02 0.143
9 15 14.98 0.02 0.133
10 17.5 17.48 0.02 0.114
11 18 17.96 0.04 0.222
12 20 20 0 0
13 21.5 21.48 0.02 0.093
14 23 22.98 0.02 0.087
15 24.5 24.48 0.02 0.082
16 41 41.04 -0.04 0.098
17 50 50 0 0
18 58 57.98 0.02 0.034
19 60 59.98 0.02 0.033
20 62.5 62.6 -0.1 0.16
21 78 77.98 0.02 0.026
22 125 125.08 -0.08 0.064
23 134 134.12 -0.12 0.09
24 144.5 144.5 0 0
25 225 225 0 0
-0.15
-0.1
-0.05
0
0.05
0 50 100 150 200 250
ero
or(
mm
)
standard reading(mm)
error vs standard reading
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IIT-Gandhinagar METROLOGY LAB
CONCULSION:
The vernier caliper used is precise and very accurate as seeing errors during
calibration.
The error in increases as we combine the blocks, it is because of loose contact.
The error in combination of gauges is the addition of caliberation error and air gap.
For small reading human error can cause to very high error which is misleading.
COMMENTS:
Make sure that slip gauges mirror finish side is pure and clean otherwise it will cause
error.
Human error can affect the results very much for small gauges.
There can be thermal expansion so we need o make sure appropriate environment of
gauges.
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 50 100 150 200 250
% e
rro
r
standard reading(mm)
% error vs standard reading