A radius is the distance between an arc and its center point. Indicate this
distance with a radius dimension line. A radius dimension line uses one
arrowhead at the arc end. Never use an arrowhead at the radius center.
Where location of the center is important and space permits, draw a
dimension line from the radius center with the arrowhead touching the arc.
Place the dimension between the arrowhead and the center. In limited space,
extend the dimension line through the radius center. If you cannot place the
arrowhead between the radius center and the arc, place it outside the arc with
a leader. Where the center of a radius is not dimensionally located, do not
indicate the center.
Where a dimension is given to the center of a radius, draw a small cross at
the center. Where location of the center is unimportant, the drawing must
clearly show that other dimensional features (such as tangent surfaces)
control the arc location.
Figure 3-27 illustrates correctly dimensioned radii.
Figure 3-27.Dimensioning radii.
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