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5. What is Vernier Bevel Protractor? About its main parts.And when,where to use it

# What is Vernier Bevel Protractor? About its main parts.And when,where to use it

## What is Vernier Bevel Protractor?

“A measuring tool by which an angle is measured with greater precision (1°/12th part or 5 minutes), vernier bevel protractor (vernier bevel protractor)”.
With the protractor head of the combination set, we can measure an angle to an accuracy of at least 1°. But through this we can measure an angle to the precision of one twelfth of a degree.

## main part

Its main parts are as follows-

### (1.)Main Scale

This is the part in which 360° of the dial is divided into equal parts, each of which is of 1°.

### (2.)Vernier scale

This scale is fixed on the swivel plate by two screws. In the middle of this scale is the zero line. 12-12 lines (parts) are drawn on either side of the zero line. These 12 parts are equal to 23 parts of the main scale.

It is fixed with the dial with the help of a clamping lever. And it is made of high carbon steel or alloy steel. Its (blade) edges are made at 45° and 60°.

### (4.)disk

This is the main part of it. Parts are made on its edge.

### (5.)dial

It is round shape and marks are made on its circumference from 0° to 360°, it is divided into four equal parts.

### (6.)Stock

It is rectangular in texture. This angle is the surface touching the job in the measuring process. And in the middle of it (stock) there is a slit (groove).

### (7.)Locking Screw

Vernier bevel protractor has two locking screws. One of which locks the locking screw dial to the disc, and locks the screw blade.

## Uses of Vernier Bevel Protractor

In addition to angle measurement, it is also used as a work holding device on the work table of the machine. By this, two types of angles can be measured both obtuse and acute angles.

## Calibration on Vernier Bevel Protractor

Marks from 1° to 360° are made on the circumference of its dial scale. Let’s take the line in front of the stock as 90°. Thus 360° is divided into four equal parts.
In this, every 10th line is marked with 0°, 10°, 20°, 30°, 40°…….
On the disc of the vernier bevel protractor there are 23 main divisions divided into 12 equal parts of the vernier.
One part of the Vernier scale = 23°/12 = 1° 55°

## Least count of vernier bevel protractor

Thus, the value of 12 parts of the vernier scale = 23°
Value of one part of Vernier scale = 23°/12
Since it is approximately equal to 2 parts of the main scale, the value of one part of the main scale = 2°
Least count = value of one part of main scale – value of one part of Vernier scale
Least count = 2° – 23°/12 = 1°/12
least count = 5 minutes
Therefore, in place of 0 – 12 on the Vernier scale, 0 – 60 minutes have been marked, due to which the measurement of Vernier is found directly in minutes.
First of all note down the zero on the Vernier scale, the full degree marks next to the zero on the main scale.
This will be the measurement of the main scale. Its After this, in the same line, see which part of the vernier meets any part of the main scale. And multiply the serial number of which the line is found by 5, from this you can find the value of Vernier scale in minutes.

Example: – If in a Vernier bevel protractor after reading 15° on the main scale, the sixth line of the vernier scale meets any line of the main scale, then what will be its total measurement?

solution:- Measurement of Main Scale = 15°
Least count of Vernier scale = 5 minutes
Value of 6 parts of Vernier = 6 × 5 = 30 minutes
Total measurement = 15°30′