3. 3
Angular Measurement
• Circles are divided into 360 equal parts,
each being a degree.
• Each of these degrees can be evenly
divided into 60 equal parts. These parts
are called minutes.
• These minutes can be evenly divided into
60 equal parts. These parts are called
seconds.
4. 4
Types Of Tools:-
• Most common tools:-
• Simple Protractor
• Multi-Use Gauge
• Combination Set
• Universal bevel protractor
16. 16
• Precision
angles to within
5' (0.083º)
• It Consists of :-
• Base
• Vernier scale
• Protractor dial
• Sliding blade
• Dial clamp nut
Universal Bevel Protractor
17. 17
Vernier Protractor
• Used to measure obtuse angle (90º-180º)
• Acute-angle attachment fastened to
protractor to measure angles less than 90º
• Main scale divided into
two arcs of 180º
• Scale divided into 12
spaces on each side of 0
• If zero on vernier scale
coincides with line on
main: reading in degrees
18. 18
Reading a Vernier
Protractor
• Note number of whole degrees between zero
on main scale and zero on vernier scale
• Proceeding in same direction, note which
vernier line coincides with main scale line
50º
Fourth
• Multiply number by 5' and add to
degrees on protractor dial
4 x 5'= 20'
Reading =
50º 20'
19. 19
Sine Bars
• Used when accuracy of angle must be
checked to less than 5 minutes
• Consists of steel bar with two cylinders
of equal diameter fastened near ends
• Centers of cylinders exactly 90º to edge
• Distance between centers usually 5 or 10
inches and 100 or 200 millimeters.
• Made of stabilized tool hardened steel
22. 22
TRY SQUARE
• A try square is a wood working or a metal
working used for marking and measuring a piece
of wood. The square refers to the tool's primary use of
measuring the accuracy of a right angle (90 degrees);
to try a surface is to check its straightness or
correspondence to an adjoining surface. A piece of
wood that is rectangular, flat, and has all edges (faces,
sides, and ends) 90 degrees is called four square.
24. 24
Dial Gauge
• The dial gauge also known as the indicating
gauge and used for checking concentricity of
rods, holes and flatness of surfaces to accuracy
of 0.01mm. These gauges are widely used on
lathe.