Vernier caliper - Digital caliper

Vernier caliper - Digital caliper

What Is Vernier Calliper?

A vernier calliper is defined as a measuring device that is used for the measurement of linear dimensions. It is also used for the measurement of diameters of round objects with the help of the measuring jaws.

Vernier Calliper Diagram

French mathematician Pierre Vernier invented the vernier scale in 1631. The main use of the vernier calliper over the main scale is to get an accurate and precise measurement.

Least Count of Vernier Calliper

The least count of vernier callipers is also known as the vernier constant. It is defined as the difference between one main scale division and one vernier scale division.

It is mathematically given as:

VC = 1 MSD – 1 VSD

Therefore, the least count of vernier calliper is 0.1 mm.

What Is Zero Error?

Zero error is defined as the condition in which the measuring device registers a reading when there should not be any reading.

The zero error of the vernier calliper is calculated as:

Actual reading = Main scale + Vernier scale – (Zero error)

There are two types of zero error:

Positive zero error: When the jaws of the vernier calliper are closed, the reading is positive and away from the actual reading of 0.00 mm. For instance, if the reading is 0.08 mm, then the zero error is +0.08 mm.

Negative zero error: When the jaws of the vernier calliper are closed, the reading is negative and away from the actual reading of 0.00 mm. For instance, if the reading is 0.10 mm, then the zero error is -0.10 mm.

How to Read Vernier Calliper?

The first step is to measure nothing through which we can check if the main and the vernier scales are aligned.

When the main scale reading and the vernier scale reading are at zero, it means there is no zero error.

Now, place a ball between the two jaws of the vernier scale.

Look at the 0 mark on the vernier scale lining with the main scale.

That gives the main scale reading.

Next, look for the point on the vernier scale, which is aligned with the main scale, which gives the vernier scale reading.

It is important to note that the readings will most of the time be in decimals.

The number before the decimal point is the main scale reading, while the number after the decimal point is the vernier scale reading.

THE DIGITAL CALIPER

The Digital Caliper (sometimes incorrectly called the Digital Vernier Caliper) is a precision instrument that can be used to measure internal and external distances extremely accurately. The example shown below is a digital caliper as the distances/measurements, are read from a LCD display. The most important parts have been labelled.

Earlier versions of this type of measuring instrument had to be read by looking carefully at the imperial or metric scale and there was a need for very good eyesight in order to read the small sliding scale. Manually operated vernier calipers can still be bought and remain popular because they are much cheaper than the digital version. Also, the digital version requires a small battery whereas the manual version does not need any power source.

Digital calipers are easier to use as the measurement is clearly displayed and also, by pressing the inch/mm button the distance can be read as metric or imperial.

The display is turned on with the on/off button. The external jaws should then be brought together until they touch and the zero button should be pressed. The digital caliper can then be used to measure distances. Always go through this procedure when turning on the display for the first time.

MEASURING EXTERNAL DISTANCES

The material to be measured is placed between the external jaws and they are carefully brought together. The locking screw is tightened so that the jaws do not move apart. The digital display can then be read. The distance can be read by in metric and imperial by pressing the inch/mm button.