TABLE OF CONTENTS Dimensions for angles, diameters, squares, arcs, and round corners are shown as follows:
Angles are measured in degrees, Fig. 5-8. If greater accuracy is needed, one degree is divided into 60 minutes and one minute is divided into 60 seconds. For reference, a circle has 360 degrees, (O), one degree has 60 minutes ([ ?]), and one minute has 60 seconds ([ ?]). Inch and millimeter measurements both measure angles in degrees.
Objects that are round or square are dimensioned as shown in Fig. 5-9. Smaller items may be dimensioned with a leader line; larger features may use extension and dimension lines. Round objects are expressed as diameters and may have DIA. after the number. Outside diameters may be labeled O.D. and inside diameters may be marked I.D. after the dimension. Symbols may be found on some drawings to indicate round or square features. Symbols precede the dimension as shown in Fig. 5-9. Round and square features are generally measured to their center lines.
Dimensions for arcs and round corners show R. or RAD. or RADIUS after the dimension, Fig. 5-10. Arcs are measured from their center lines.
