VERNIER CALIPER
PRESENTED BY:
ABINASH DAS
MECHATRONICS ENGINEERING
(3RD BATCH)
A GOVT. OF INDIA SOCIETY
CENTRAL TOOL ROOM AND TRAINING CENTRE
THE VERNIER CALIPER
THIS INSTRUMENT MAY BE USED TO MEASURE OUTER
DIMENSIONS OF OBJECTS (USING THE MAIN JAWS), INSIDE
DIMENSIONS (USING THE SMALLER JAWS AT THE TOP), AND
DEPTHS (USING THE STEM).
HISTORY
 CALLIPERS WITHOUT A VERNIER SCALE ORIGINATED IN ANCIENT CHINA
AS EARLY AS THE QIN DYNASTY (9 AD)
 THE SECONDARY SCALE, WHICH CONTRIBUTED EXTRA PRECISION, WAS
INVENTED IN 1631 BY FRENCH MATHEMATICIAN PIERRE VERNIER
(1580–
1637)
 IN SOME LANGUAGES, THE VERNIER SCALE IS CALLED A NONI'S. IT
WAS ALSO COMMONLY CALLED A NONI'S IN ENGLISH UNTIL THE
END OF THE 18TH CENTURY.[4] NONIE'S IS THE LATIN NAME OF
THE PORTUGUESE ASTRONOMER AND MATHEMATICIAN PEDRO
NUNS (1502–1578),
PARTS OF A VERNIER CALIPER
Inner jaws
For internal measurements
Fixed jaw
Movable jaw
Vernier scale
Lock
Fixed jaw
Fine adjustment screw
Main or meter
scale
Movable jaw
For external measurements
Outer jaws
Depth rod
(to measure
depth)

CONSTRUCTION
THE INDICATING SCALE IS CONSTRUCTED SO THAT WHEN ITS ZERO POINT IS
COINCIDENT WITH THE START OF THE DATA SCALE,
 ITS GRADUATIONS ARE AT A SLIGHTLY SMALLER SPACING THAN THOSE ON THE
DATA SCALE AND SO NONE BUT THE LAST GRADUATION COINCIDE WITH ANY
GRADUATIONS ON THE DATA SCALE. N GRADUATIONS OF THE INDICATING SCALE
COVER N−1 GRADUATIONS OF THE DATA SCALE.
SPECIAL DEFINITIONS ON CALIPER MEASUREMENTS
LEAST COUNT- LEAST COUNT REFERS TO THE SMALLEST DISTANCE THAT CAN BE MEASURED
USING AN INSTRUMENT. MOST OF THE VERNIER CALIPERS HAVE A LEAST COUNT OF
0.1MM.
LEAST COUNT = LENGTH OF 1 MSD – LENGTH OF 1 VSD
WHERE MSD AND VSD REFER TO MAIN SCALE DIVISION AND VERNIER SCALE DIVISION
RESPECTIVELY
GENERALLY N DIVISIONS ON MAIN SCALE COINCIDE WITH N-1 DIVISIONS ON VERNIER SCALE
1 VSD IS EQUIVALENT TO (N-1)/N MAIN SCALE DIVISIONS
USING THE FORMULA FOR LEAST COUNT, WE GET
LC = 1 MSD – 1VSD
= 1 MSD – (N-1)/N MSD
= 1/N MSD
LENGTH FORMULA FOR A VERNIER CALIPER
ALTHOUGH THE LEAST COUNT MAY VARY BETWEEN DIFFERENT CALIPERS, THE LENGTH
FORMULA FOR ANY CALIPER IS AS FOLLOWS:
LENGTH = MSR + (VSR * LC)
WHERE MSR, VSR AND LC REFER TO MAIN SCALE READING, VERNIER SCALE READING
AND LEAST COUNT RESPECTIVELY.
0
0
ERROR IN A VERNIER CALIPER
ANY VERTICAL CALIPER MAY HAVE TWO TYPES OF ERRORS:
1.POSITIVE ZERO ERROR
2. NEGATIVE ZERO ERROR
POSITIVE ZERO ERROR –
OCCURS WHEN THE ZERO OF THE VERNIER SCALE IS TO THE RIGHT OF THE
VERNIER SCALE WHEN THE TWO JAWS ARE IN CONTACT.
TO TAKE THE PRECISE VALUE FOR THE MEASUREMENT WE ARE TAKING, WE
HAVE TO SUBTRACT THE VALUE OF THE POSITIVE ZERO ERROR FROM THE
OBTAINED MEASUREMENT.
NEGATIVE /POSITIVE ZERO ERROR –
OCCURS WHEN THE ZERO OF THE VERNIER SCALE IS TO THE LEFT OF THE VERNIER SCALE WHEN
THE TWO JAWS ARE IN CONTACT.
OCCURS WHEN THE ZERO OF THE VERNIER SCALE IS TO THE RIGHT OF THE VERNIER SCALE
WHEN THE TWO JAWS ARE IN CONTACT.
TO TAKE THE PRECISE VALUE FOR THE MEASUREMENT WE ARE TAKING, WE HAVE TO ADD THE
VALUE OF THE NEGATIVE / POSITIVE ZERO ERROR TO THE OBTAINED MEASUREMENT.
Positive Zero Error
0
0
0
Negative Zero Error
0
NO ZERO ERROR
NO ZERO ERROR IS THE PRECISE ARRANGEMENT OF THE METER SCALE AND
THE VERNIER SCALE SO THAT THE ZEROS OF BOTH SCALES FIT EACH OTHER
AS FOLLOWS:
0
0
TO TAKE PRECISE MEASUREMENTS, WE HAVE TO ENSURE THAT THE CALIPER
WE ARE USING IS OF NO ZERO ERROR.
TAKING A MEASUREMENT
1.
FIRST FIND WHETHER THERE’S AN ERROR ON THE CALIPER.
2.
SECOND FIND ITS LEAST COUNT(LC)
3.
PLACE THE OBJECT BETWEEN THE APPROPRIATE JAWS (OUTER/INNER) OR ON THE
DEPTH ROD ACCORDING TO THE MEASUREMENT.
4.
THE READING OF THE MAIN SCALE (MSR) WHICH IS TO THE LEFT OF THE ZERO OF
THE VERNIER SCALE IS THE MAIN SCALE READING
5.
NOW LOOK UP FOR THE NO. OF DIVISIONS ON THE VERNIER SCALE WHICH EXACTLY
COINCIDES WITH ANY OF THE MAIN SCALE READING. THIS IS THE VERNIER SCALE
READING(VSR)
6.
THE LENGTH OF THE OBJECT IS CALCULATED USING THE FORMULA: LENGTH = MSR
+ (VSR * LC)
7.
IF THERE’S AN ERROR IN THE CALIPER ADD OR SUBTRACT DEPENDING ON THE TYPE
(POSITIVE ERROR/NEGATIVE ERROR)
MEASURING WITH OUTER JAWS
1. FIRST FIND WHETHER THERE’S AN ERROR ON THE CALIPER.
2. SECOND FIND ITS LEAST COUNT(LC)
3. PLACE THE OBJECT BETWEEN THE OUTER JAWS
4. THE READING OF THE MAIN SCALE (MSR) WHICH IS TO THE LEFT OF THE
ZERO OF THE VERNIER SCALE IS THE MAIN SCALE READING
5. NOW LOOK UP FOR THE NO. OF DIVISIONS ON THE VERNIER SCALE WHICH
EXACTLY COINCIDES WITH ANY OF THE MAIN SCALE READING. THIS IS THE
VERNIER SCALE READING(VSR)
6. THE LENGTH OF THE OBJECT IS CALCULATED USING THE FORMULA: LENGTH
= MSR + (VSR * LC)
7. IF THERE’S AN ERROR IN THE CALIPER ADD OR SUBTRACT DEPENDING ON
THE TYPE (POSITIVE ERROR/NEGATIVE ERROR)
MEASURING WITH INNER JAWS
1. FIRST FIND WHETHER THERE’S AN ERROR ON THE
CALIPER.
2. SECOND FIND ITS LEAST COUNT(LC)
3. PLACE THE OBJECT BETWEEN THE INNER JAWS
4. THE READING OF THE MAIN SCALE (MSR) WHICH IS TO THE LEFT OF THE ZERO OF
THE VERNIER SCALE IS THE MAIN SCALE READING
5. NOW LOOK UP FOR THE NO. OF DIVISIONS ON THE VERNIER SCALE WHICH EXACTLY
COINCIDES WITH ANY OF THE MAIN SCALE READING. THIS IS THE VERNIER SCALE
READING(VSR)
6. THE LENGTH OF THE OBJECT IS CALCULATED USING THE FORMULA: LENGTH = MSR +
(VSR * LC)
7. IF THERE’S AN ERROR IN THE CALIPER ADD OR SUBTRACT DEPENDING ON THE TYPE
(POSITIVE ERROR/NEGATIVE ERROR)
MEASURING
WITH
DEPTH
ROD
Vernier caliper
1. FIRST FIND WHETHER THERE’S AN ERROR ON THE CALIPER.
2. SECOND FIND ITS LEAST COUNT(LC)
Depth rod
3. KEEP THE OBJECT IN CONTACT WITH THE BRIM OF THE VERNIER CALIPER.
EXTEND THE DEPTH ROD UNTIL IT MEETS THE DEPTH TO BE MEASURED.
Object whose depth
is to be measured
4. THE READING OF THE MAIN SCALE (MSR) WHICH IS TO THE LEFT OF THE ZERO
OF THE VERNIER SCALE IS THE MAIN SCALE READING.
5. NOW LOOK UP FOR THE NO. OF DIVISIONS ON THE VERNIER SCALE WHICH
EXACTLY COINCIDES WITH ANY OF THE MAIN SCALE READING. THIS IS THE
VERNIER SCALE READING(VSR).
6. THE LENGTH OF THE OBJECT IS CALCULATED USING THE FORMULA: LENGTH =
MSR + (VSR * LC).
7. IF THERE’S AN ERROR IN THE CALIPER ADD OR SUBTRACT DEPENDING ON
THE TYPE (POSITIVE ERROR/NEGATIVE ERROR).
In figure 4 above, the first significant figures are taken as the
main scale reading to the left of the Vernier zero, i.e. 3.7 cm.
The remaining digits are taken from the Vernier scale reading
that lines up with any main scale reading, (i.e. 0.46 mm or
0.046 cm) on the Vernier scale. Thus the reading is
3.746
HOW TO READ AND USE THE
VERNIER CALIPER?
The reading here is 3.7 mm or 0.37 cm.
The reading here is 15.8 mm or 1.58 cm.
CONCLUSION
 THESE ARE USED FOR MAKING MEASUREMENTS THAT ARE
ACCURATE TO A HUNDREDTH OF A MILLIMETRE.
IT CAN BE USED TO MEASURE INTERNAL AS WELL AS EXTERNAL
DIMENSIONS, AND DEPTHS OF FEATURES LIKE STEPS AND BLIND
HOLES, IN SMALL COMPONENTS. NOWADAYS MANY MACHINISTS.
THE ADVANTAGE TO USING A VERNIER CALLIPER IS THAT THE
MEASUREMENT IS GOING TO BE MORE ACCURATE. RULERS AND
TAPE MEASURES ARE NOT ACCURATE ENOUGH WHEN A PRECISE
MEASUREMENT …
ANY
QUERIES???
THANK…