Chapter 4 CAD Commands and Functions 107
are defi by the intersection of a major axis fined
and minor axis. The axes intersect at the center
point of the object and divide the ellipse into
four quadrants. The
Ellipse
command draws the
shape automatically based on points specifiedfi
for the major and minor axis endpoints.
Ellipses can be drawn by several methods.
One method is to locate the two axes by select-
ing two endpoints of one axis and one endpoint
of the other axis, Figure 4-8. Another method is
to locate the ellipse’s center, and then specify one
endpoint of each axis. A third method is to pick
the ellipse’s major axis endpoints and then enter
a rotation angle.
AutoCAD Example:
Command: ellipse↵
Specify axis endpoint of ellipse or [Arc/Center]: 4,4↵
Specify other endpoint of axis: 8,4↵
Specify distance to other axis or [Rotation]: 6,5↵
Command:
Rectangle
A square or rectangle can be drawn using
the
Line
command. However, the
Rectangle
com-
mand automates the process of creating a square
or rectangle, Figure 4-9. Most CAD software
provides at least two methods for constructing
a rectangle. These are specifying the width and
height of the rectangle or specifying opposite
corners of the rectangle.
AutoCAD Example:
Command: rectangle↵
Specify fi rst corner point or [Chamfer/Elevation/Fillet/
Thickness/Width]: 1,5↵
(or pick a point on screen)
Specify other corner point or [Area/Dimensions/
Rotation]: 6,3↵
(or pick a point on screen)
Command:
Polygon
The
Polygon
command automates the
construction of a regular polygon. A regular
polygon is an object with sides of equal length
and included angles. The
Polygon
command can
create an object with three or more sides. A com-
mon approach used by many CAD programs
is to either inscribe the polygon within a circle
or circumscribe it about a circle, Figure 4-10.
The information required in these instances
includes the radius of the circle, method desired,
and number of sides for the polygon. Another
method available in some CAD programs is to
defi the end points of one side of the polygon. fine
The software generates the remaining sides to
create a regular polygon.
AutoCAD Example:
Command: polygon↵
Enter number of sides 4: 5↵
Specify center of polygon or [Edge]: 1,5↵
(or pick a
point on screen)
Enter an option [Inscribed in circle/Circumscribed
about circle] I: c↵
Specify radius of circle: 2↵
Command: ↵
POLYGON Enter number of sides 5: 5↵
Specify center of polygon or [Edge]: 6,5↵
(or pick a
point on screen)
Enter an option [Inscribed in circle/Circumscribed
about circle] C: i↵
Specify radius of circle: 2↵
Command:
Text
You can add text to a drawing using the
Text
command. This is important for placing
notes, specifications, and other information on a fi
Figure 4-9. You can draw a rectangle by specifying
opposite corners.
Figure 4-8. There are several ways to create ellipses.
In this example, points are picked to identify the major
and minor axes.