Bevel Protractor

It is the simplest angle measuring instrument. A simple vernier bevel protractor with its various elements is shown in fig.2.27. The body of the bevel protractor is designed in such a way that its back is flat and there are no projections beyond its back. The base plate is attached to the main body and an adjustable blade is attached to a circular plate containing vernier scale. The main body carries a main scale graduated in degrees. The adjustable blade which is capable of rotating freely about the centre of the main scale engraved on the body of the instrument can be locked in any position. An acute angle attachment is provided at the top. The base of the base plate is made flat so that it could be laid flat upon the work piece. The blade can be moved along throughout its length and can also be reversed. The acute angle attachment can be readily fit into the body and clamped in any position.

Universal Bevel protractor: The protractor dial is slotted to hold a blade which can be rotated with the dial to the required angle. It can also be adjusted independently to any desired length. The blade can be locked in any position. This instrument is capable of readings precisely within

5 minutes.

Optical Bevel protractor: This instrument is capable of taking readings within 2 minutes of an arc. The interval circular scale is graduated in divisions of 10 minutes of arc. Readings are taken with the help of optical magnifying system which is an integral part of the instrument.

Uses of Bevel protractor:

The bevel protractors can be used to test the flatness, squareness, parallelism, straightness, angular measurements, etc.

Types of bevel protractors:

As per IS practice, there are two bevel protractors, namely;

1) Mechanical Bevel protractor