15-10-2012, 05:26 PM
Angular Measurement
Angular_Measurement.ppt (Size: 1.76 MB / Downloads: 87)
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 minutes.
Most common tools
Simple Protractor
Multi-Use Gage
Combination Set
Universal bevel protractor
Sine bar
Sine plate
Universal Bevel Protractor
Precision angles to within 5' (0.083º)
Consist of base
Vernier scale
Protractor dial
Sliding blade
Dial clamp nut
Vernier Protractor
Used to measure obtuse angle (90º-180º)
Acute-angle attachment fastened to protractor to measure angles less than 90º
Main scale divided intotwo arcs of 180º
Scale divided into 12 spaces on each side of 0
If zero on vernier scalecoincides with line on main: reading in degrees
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