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Vernier Caliper

Last updated date: 25th Nov 2023
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Introduction to Vernier Caliper

A vernier scale which is named after Pierre Vernier is defined as a visual aid to take an accurate measurement reading between two graduation markings on a linear scale by using mechanical interpolation. It is used to calculate the internal and external diameters of hollow cylinders. It is also used for the measurement of diameters of round objects with the help of the measuring jaws. It is an extremely precise measuring instrument. It is a device that is used to calculate very accurate linear measurements. In simple words, it measures the straight linear distance between two points. It is a very useful tool to carry in the toolbox.

A vernier caliper is also used to measure the diameter of round and cylindrical objects, by positioning the jaws of the caliper on either side of the circumference.


Vernier caliper is a very useful tool to carry in the toolbox.


Vernier Scale

The vernier scale measures accurate dimensions. It has two scales; a normal large scale (main scale) and a scale inside it is used to calculate measurements without any error.


The vernier scale gives accurate measurement because it is based on the concept of vernier acuity. The vernier acuity is a type of visual acuity which measures the misalignment of two line segments. The human eye can easily detect aligned and non-aligned lines.


The vernier caliper generally shows either metric or imperial measurements, but some calipers measure in both.


Uses of Vernier Caliper

There are three major uses of Vernier Calipers which are as follows:

  •   It is used to measure the internal diameter of a tube or cylinder.

  •  It is useful in measuring the length of the object.

  • Traditionally; a vernier caliper is used to measure the diameter of circular objects.


Apart from these Vernier calipers are useful for many purposes such as for the industrial domain as well as for professionals and engineering purposes.


Purposes of Vernier Caliper

Vernier calipers are useful for several purposes, and that's why it has become handy in the industrial domain, for professionals and engineers. This article lists some of the major uses of a vernier caliper below:

  • Educational Purpose

Vernier calipers are used in engineering research classes to train school students. It is used to assist intermediate and high school physics students to take measurements of different objects with ‘zero error’.

  • Steel Sector

Vernier calipers are an important device in the steel industry. It is used to measure the inner and outer dimensions of objects that are made up of steel. It is also used to measure the thickness of steel objects of different shapes.

  • Medical Sector

The surgical instruments of the medical sector use vernier calipers because the dimensions of medical instruments need to be measured with utmost precision for medical use.

  • Scientific Labs

Scientific Labs use vernier calipers for huge arrays of purposes. For example, to study the effect of thermal variations in different metals that differ in chemical properties. Vernier caliper is also used to precisely measure the objects which are used to join two pieces of two objects thereby employing high skillful precision.

  • Aerospace Sector

No doubt, the aerospace aviation industry requires extremely high precision. Even a slight change in the dimension of an object can lead to major damage and also to the things related to it. Various types of vernier calipers with high precise readings like digital dial calipers are used to tackle such kind of damage to the system.


How to Use a Vernier Caliper?

A vernier caliper is usually used to measure the diameter of circular objects. The circular jaws of the vernier caliper fit perfectly on the circumference of round objects. Vernier caliper consists of two scales, the main scale which is fixed, and a moving vernier scale. The main scale has readings in millimeters. Unlike standard scales, a vernier caliper can measure readings precisely up to 0.001 cm. For accurate measurement, a vernier scale is used along with a vernier caliper.


Range of Vernier Calipers

The maximum capacity of a vernier caliper is determined by the difference between the largest and the smallest measurement reading. Usually, it is the entire length of the main scale of the vernier caliper. The vernier calipers normally have a range of 300 mm. However, vernier calipers of smaller ranges are also available in the market.


Vernier Reading: The smallest measurable distance that can be captured by a vernier caliper is called a vernier reading. It is also called the "Resolution" of a vernier caliper. The imperial vernier calipers normally have a resolution of 0.001 inches, and the resolution or smallest measurable distance of a metric vernier caliper varies from 0.02 mm to 0.05 mm. The resolution is mentioned at the end of a Vernier scale.


Tolerance: Tolerance or instrument error is the accuracy of the readings of a Vernier caliper. Vernier calipers are normally used to calculate low tolerance measurement readings. Low tolerance measurement readings give reliable and accurate results, as the probability of error is minimum. In general, the tolerance of the Vernier calipers is about +/- 0.03mm (+- 0.0015 in).

FAQs on Vernier Caliper

1. What are the types of vernier caliper?

There are three types of vernier caliper based on Indian standards.

The First Type- This caliper contains jaws on both sides for internal and external measurements, and has a needle to measure depth. These vernier calipers are normally made up of steel having a hardness of about 650±50 HV (Vickers Pyramid Number). The below-given image is the first type of vernier caliper.

The Second Type- The second type of vernier caliper doesn't have separate jaws for external and internal measurements. It contains one set of jaws to measure both external and internal measurements. The measuring faces of the jaws of the second type of vernier caliper are suitable to take both external and internal measurements.

2. What are the precautions while using the Vernier Caliper?

  • The smaller jaws of a vernier caliper are used to measure the internal diameter of an object. The primary jaws are used to measure the external diameter.

  • The Vernier Scale Reading: A caliper has the main scale (fixed) and a sliding (Vernier) scale. In addition to it, the vernier scale also has an engraved label to depict the value it represents.

  • Unlocking the Screw: Some of the vernier calipers models have a locking screw in them. One must ensure to unlock those screws before using the vernier caliper. You should twist the screw in the counterclockwise direction to unlock it.

3. What is the difference between a vernier and a caliper?

Caliper is a device which is used to measure the thickness between two surfaces of an object, while vernier is a type of secondary scale with finer graduations (for precise measurements) than the primary scale of a measuring device. The vernier scale measures readings between the graduations of the larger scale.

4. What is the range of Vernier Calipers?

The maximum capacity of a Vernier caliper is the difference between the smallest and largest measurement reading. Usually, it is the total length of the main scale. Vernier calipers, generally, have a range of 300 mm.

5.  What is the meaning of Vernier Reading?

Vernier reading is the smallest measurable distance captured by a Vernier caliper. It is also termed as "Resolution" of the Vernier caliper. Imperial Vernier calipers have a resolution of 0.001 inches. The resolution of metric Vernier calipers varies from 0.02mm to 0.05mm. The resolution is normally indicated at the end of the Vernier scale.

6.   What are the main elements of Vernier Calipers?

The main elements of the vernier caliper are the

  • Main Scale

  • Vernier scale

  • Thumbscrew

  • Lock screw

  • Depth Rod

  • A fixed jaw, and

  • Sliding jaw 

7.   What is the meaning of Least count in Vernier Calipers?

The difference between the value of one main scale division and the value of one Vernier scale division is known as the least count of the Vernier. The least count of vernier calipers is the smallest value that we can measure from this device. To calculate the least count of vernier calipers is the value of one main scale division divided by the total number of divisions on the vernier scale.

8.   What is the principle of Vernier Calipers?

A scale cannot measure objects which are smaller than 1mm but a vernier caliper can measure objects up to 1mm. As already known the vernier caliper has two scales: the main scale and the vernier scale together this arrangement is used to measure very small lengths like 0.1mm.

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