You can create diameter dimensions for circles or arcs to measure their diameters. Creating diameter dimensions resembles creating radial dimensions.
You can create various diameter dimensions based on the location and size of circles or arc, and the settings of the dimension style. Either drawing a center mark or line is controlled by the dimension style. If the dimension line is created inside a circle or arc, the center mark or line is not drawn. The system variable DIMCEN controls whether the center mark or line is displayed.
To create a diametral dimension
Choose Dimensions > Diameter.
Select the arc or circle.
Specify the dimension line location.
Command line DIMDIAMETER
Select the circle (A), and then specify the dimension line location (B).
DIMCENTER: Creates the center mark or the centerlines of circles and arcs
DIMDIAMETER: Creates diameter dimensions for circles and arcs
DIMRADIUS: Creates radial dimensions for circles and arcs
QDIM: Quickly creates a dimension
System Variables Reference
DIMATFIT: Determines how dimension text and arrows are arranged when space is not sufficient to place both within the extension lines
DIMCEN: Controls drawing of circle or arc center marks and centerlines by the DIMCENTER, DIMDIAMETER, and DIMRADIUS commands
DIMJUST: Controls the horizontal positioning of dimension text
DIMTAD: Controls the vertical position of text in relation to the dimension line
DIMTIH: Controls the position of dimension text inside the extension lines for all dimension types except ordinate
DIMTMOVE: Sets dimension text movement rules
DIMTOFL: Controls whether a dimension line is drawn between the extension lines even when the text is placed outside
DIMTOH: Controls the position of dimension text outside the extension lines
DIMUPT: Controls options for user-positioned te