1. The document discusses bevel protractors, which are instruments used to measure angles. 2. It defines key angle measurement terms like degrees, minutes, and seconds. 3. It describes the main parts of a bevel protractor including the body, base, blade, locking nut, adjusting screw, and eyepiece. It is used to measure angles by placing the blade against the workpiece.

1. 1
Prepared by,
Mr. S. B. Kamble
Department of Mechanical Engineering
Sharad Institute of Technology, College of Engineering, Yadrav
Bevel Protractor
Subject – Metrology and Quality Control

2. Bevel
Protractor

3. Unit of angle derived from theoretical considerations is the radian, defined as the
angle subtended at the centre of a circle by an are length equal to radius of circle.
The angle is defined as the opening between two lines which meet at a point.
Ɵ
Circle is divided into 360 parts, each part is called a degree ( º).
Each degree is divided in 60 minutes ( ') and each minute into 60 Seconds ( “)
Angle

4. Angle Measuring Instruments

5. Ɵ
Ɵ = 40°
Angle Measurement

6. Bevel Protractor
Body
1. Body
Eyepiece
Acute Angle
Attachment
Base
Blade
Adjusting Screw
Locking
Nut
Blade Locking
Nut
2. Base
8. Acute angle attachment
3. Blade
4. Blade Locking Nut
5. Adjusting screw
6. Locking Nut
7. Eyepiece

7. Angle Measurement by Bevel Protractor
Workpiece
Ɵ

8. Angle Measurement by Bevel Protractor
Degree ( º)
Minutes ( ')
Least Count = 60'/12
Main Scale
Vernier Scale
Least Count = 5' (Minute)
Angle Measurement:
Main Scale Reading
Vernier Scale
reading = 3rd line
=28º
Total Reading = Main Scale Reading + Vernier Scale Reading X (LC)
= 28º+3 X (5')
Total Reading = 28º15'

10. 10