Radial
dimensions measure the radii and diameters of arcs and circles with optional
centerlines or a center mark.
There are two types of radial dimensions:
- DIMRADIUS measures the
radius of an arc or circle, and displays the dimension text with
the letter R in front of it.
- DIMDIAMETER measures the
diameter of an arc or circle, and displays the dimension text with
the diameter symbol in front of it.
For horizontal dimension text, if the angle
of the radial dimension line is greater than 15 degrees from horizontal,
a hook line, also called a dogleg or landing, one
arrowhead long, is created next to the dimension text.
Control Extension Lines
When
an arc is dimensioned, the radial or diametric dimension does not have
to be positioned along the arc directly. If a dimension is positioned
past the end of an arc, either an extension line will be drawn that
follows the path of the arc being dimensioned or no extension line
will be drawn. When the extension line is suppressed (off), the
dimension line of the radial or diametric dimension is drawn through
the center point of the arc instead of to the extension line.
The DIMSE1 system variable
controls whether or not a radial or diametric dimension will be
drawn with an extension line when it is positioned off the end of
an arc. When the display of the arc extension line is not suppressed, a
gap between the arc and arc extension line is made. The size of
the gap drawn is controlled with the DIMEXO system variable.
Control Centerlines and
Center Marks
Depending
on your dimension style settings, center marks and lines generate automatically
for diameter and radius dimensions. They are created only if the
dimension line is placed outside the circle or arc. You can create
centerlines and center marks directly with the DIMCENTER command.
You can control the size and visibility of centerlines
and center marks on the Modify Dimension Style dialog box, Symbols
and Arrows tab, under Center Marks. You can also access this setting
with the DIMCEN system variable.
The size of the centerline is the length of
the centerline segment that extends outside the circle or arc. It
is also the size of the gap between the center mark and the start
of the centerline. The size of the center mark is the distance from
the center of the circle or arc to the end of the center mark.
Create Jogged Radius Dimensions
With
the DIMJOGGED command, you
can create jogged radius dimensions, also called “foreshortened
radius dimensions,” when the center of an arc or circle is located
off the layout and cannot be displayed in its true location. The
origin point of the dimension can be specified at a more convenient location
called the center location override.
You can control the default angle of the jog
in the Modify Dimension Style dialog box, Symbols and Arrows tab,
under Radius Dimension Jog.
Once a jogged radius dimension is created, you
can modify the jog and the center location override by
- Using grips to move the features
- Changing the locations of the features
with the Properties palette
- Using STRETCH
NoteJogged radius dimensions
can be viewed but not edited in versions previous to AutoCAD 2006.
Also, if you make dramatic changes to the associated geometry, you
may get unpredictable results for the jogged radius dimension.
To create a diameter dimension
-
- Select the arc or circle to dimension.
- Enter options as needed:
- To edit the dimension text content, enter t (Text)
or m (multiline text). Editing within
or overwriting the brackets (<>) changes or removes the dimension
value. Adding text before or after the brackets appends text before
or after the dimension value.
- To change the dimension text angle, enter a (Angle).
- Specify the leader line location.
To create a radius dimension
-
- Select an arc, circle, or polyline arc
segment.
- Enter options as needed:
- To edit the dimension text content, enter t (Text)
or m (multiline text). Editing within
or overwriting the brackets (<>) changes or removes the dimension
value. Adding text before or after the brackets appends text before
or after the dimension value.
- To edit the dimension text angle, enter a (Angle).
- Specify the leader line location.
To create a jogged radius
dimension
-
- Select an arc, circle, or polyline arc
segment.
- Specify a point for the dimension origin
(the center location override).
- Specify a point for the dimension line
angle and the dimension text location.
- Specify another point for the location
of the dimension jog.
To create centerlines automatically
with radial dimensions
-
- In the Dimension Style Manager, select
the style you want to change. Click Modify.
- In the Modify Dimension Style dialog
box, Symbols and Arrows tab, under Center Marks, click Line.
- In the Size box, enter the length of
the centerline overshoot. Click OK.
- Click Close to exit the Dimension Style
Manager.
The example area in the
dialog box displays the results of your changes.
To create centerlines or
center marks on an arc or circle
-
- In the Dimension Style Manager, select
the style you want to change. Click Modify.
- In the Modify Dimension Style dialog
box, Symbols and Arrows tab, under Center Marks, click Line.
- In the Size box, enter the length of
the centerline overshoot. Click OK.
- Click Close to exit the Dimension Style
Manager.
- Select an arc or a circle.
To change the display arc
extension line for radial or diametric dimensions
- Select the radial or diametric dimension
for which you want to suppress the arc extension line.
- Right-click in the drawing. Click Properties.
- In the Properties palette, Lines &
Arrows category, click Ext Line.
- Click the arrow next to Ext Line, and
select On or Off from the list.
- Select On to display the arc extension
line.
- Select Off to suppress the display of
the arc extension line.
- Press Esc to deselect the selected dimension.
CommandsDIMCENTER
Creates the center mark
or the centerlines of circles and arcs.
DIMDIAMETER
Creates a diameter dimension
for a circle or an arc.
DIMJOGGED
Creates jogged dimensions
for circles and arcs.
DIMRADIUS
Creates a radius dimension
for a circle or an arc.
DIMSTYLE
Stores the name of the
current dimension style.
QDIM
Creates a series of
dimensions quickly from selected objects.
System VariablesDIMATFIT
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.
DIMEXO
Specifies how far extension
lines are offset from origin points.
DIMJOGANG
Determines the angle
of the transverse segment of the dimension line in a jogged radius
dimension.
DIMJUST
Controls the horizontal
positioning of dimension text.
DIMSE1
Suppresses display of
the first extension line.
DIMTAD
Controls the vertical
position of text in relation to the dimension line.
DIMTXTDIRECTION
Specifies the reading
direction of the dimension text.
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 text.
