NAME OF EXERCISE: MEASURING WITH MICROMETER
TOOLS REQUIRED:
micrometer
MATERIALS REQUIRED: cotton
waste, kerosene. Round stock.
PROCEDURE
I.
Select a suitable range of micrometer.
II. FIND OUT THE LEAST COUNT OF THE MICROMETER.
1. To find out
the pitch of the micrometer, note down the linear distance moved after one
complete revolution of the thimble.
2. Note down
the total number of division on the thimble scale.
3. Calculate
the least count by the equation,
III.
CHECKING THE ZERO ERROR OF THE MICROMETER
1. Bring the spindle
tip on to the anvil of the screw gauge.
2. When
touching, note down the zero line of the thimble scale coincided with the datum
line of the main scale.
3. If the zero
line is below the datum line, the error will be positive. Note down the number
of division zero line of thimble scale towards the datum line, along with a positive
sign.
4. If the zero
line is above the datum line, the error will be negative. Note down the number
of division zero line of thimble scale towards the datum line, along with a
negative sign.
5. Find out
the value of zero error by multiplying the least count with zero error.
IV.
MEASURE THE OUT SIDE DIAMETER OF THE ROUND STOCK
1. Clean the surface to be
measured.
2. Place the work piece in
between the anvil and spindle.
3. Rotate the thimble
scale until the spindle just touches the work surface and ensure the tightness
with the ratchet stock.
4. Take the main scale
reading.
5. Take the thimble scale reading.
6. Find out the total
reading by using the equation,
7. For getting actual
reading, use the formula
8. Repeat the
steps 2 to 7, note down the reading and take the average for final reading.
TABULAR COULUMN
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SL.NO.
|
MAIN SCALE READING
|
THIMBLE SCALE READING
|
LEAST COUNT
|
TOTAL READING
|
ACTUAL READING
|
FINAL READING
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1
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2
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3
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4
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All dimensions are in mm
SAMPLE CALCULATION
1.
TO FIND OUT
THE LEAST COUNT OF THE MICROMETER,
Pitch of
the micrometer=________mm
Number
of divisions on the thimble scale=______mm
Least
count=(1/50)x0.5
=0.01mm
2.
TO FIND OUT
THE ZERO ERROR OF THE MICROMETER,
Zero error value=least count x ___________=__________mm
3.
TO FIND OUT
THE ACTUAL READING,
Main scale reading=__________mm
Thimble scale reading=_________mm
Total reading= main scale reading +
( thimble scale reading x least count )
=________________+(______________x_____________)
=____________mm
Actual reading= Total reading –
Zero error value
=_______________-______________
=________mm
Final reading= average of total
reading
=(____________+____________+__________+_________)/4
= ___________mm
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