Chapter 4: Fundamentals III
After completing this Chapter, you will be able to use the following
features:
•Advanced Drawing commands
•Construction commands
•Modify Commands
Advanced Drawing Commands
AutoCAD provides various drawing commands that make it
possible to create geometric figures more easily and accurately.
Construction lines
Polygon
Ellipse
Polyline
Text
Tables
Creating and Modifying Table Styles
Construction lines
The XLINE command draws construction lines that extend infinitely
in both directions from the point selected.
Invoke the XLINE command from the Draw panel
Available options for XLINE include:
Horizontal - Draws a construction line through a point parallel to the
X axis of the current UCS.
Vertical - Draws a construction line through a point parallel to the Y
axis of the current UCS.
Angle - Draws a construction line at a specified angle.
Bisect - Draws a construction line through the first point bisecting the
angle determined by the second and third points, with the first point
being the vertex.
Offset - Draws a construction line parallel to and at the specified
distance from the selected line object.
Construction lines
The RAY command draws lines that extend infinitely in one
direction from the selected point.
The ray is drawn starting at the first point and extending
infinitely in one direction through the second point. AutoCAD
continues to prompt for through points until you provide a null
response to terminate the command sequence.
Polygon
POLYGON command draws 2D polygons (edges with equal length).
The number of sides can be anywhere from 3 (which forms an
equilateral triangle) to 1024.
Invoke the POLYGON command from the Draw panel.
Options include:
Inscribed in circle selection draws polygon of equal
length for all sides inscribed inside an imaginary circle
having the same diameter as the distance across opposite
polygon corners.
Circumscribed about circle selection draws polygon
circumscribed around the outside of an imaginary circle
having the same diameter as the distance across the
opposite polygon sides.
Edge selection allows you to draws polygon by specifying
the endpoints of the first edge.
Ellipse
ELLIPSE command draws an ellipse or an elliptical arc. Invoke the
ELLIPSE command from the Draw panel.
Options include:
Ellipse by Defining Axis Endpoints selection draws an ellipse by
specifying the endpoints of the axes.
Ellipse by Defining the Center of the Ellipse selection draws an
ellipse by defining the center point and axis end-points.
Ellipse by Specifying the Rotation Angle selection draws an
ellipse by specifying a rotation angle after defining two endpoints of
one of the two axes.
Polyline
PLINE command draws connected sequence of segments (straight line
segments, arc segments, or a combination of the two) created as a single
object.
The versatile PLINE command also draws lines and arcs of different
widths, linetypes, tapered lines, and a filled circle.
Invoke the PLINE command from the Draw panel.
By default, AutoCAD prompts for Start point of the polyline and
then prompts for next point or choose one of the options:
Arc selection draws a polyline arc.
Close and Undo selection work similarly to the corresponding
options in the LINE command.
Width selection prompts to specify a starting and an ending width
for a wide segment.
Halfwidth selection is similar to the width option, including the
prompts, except it lets you specify the width from the center of a
wide polyline to one of its edges.
Length selection continues the polyline in the same direction as
the last segment for a specified distance.
Text
AutoCAD provides several text related commands and tools (including a
spell checker) that greatly reduce the tedium of text placement and the
time it takes.
Single-line text
Multi-line text
Editing text
Find and Replace
Justifying Text
Spell check
Creating and Modifying text styles
Single-line text
The TEXT command creates one or more lines of text, ending
each line when you press ENTER. Each text line is an
independent object that can be relocated, reformat, or otherwise
modify.
Options include:
Start point selection specifies a start point for the text
object.
Justify selection controls justification of the text. The
available justification includes: Align, Fit, Center,
Middle, Right, Top: Left-Center-Right, Middle: LeftCenter-Right and Bottom: Left-Center-Right.
Style selection specifies the text style, which determines
the appearance of the text characters.
Multi-line text
The MTEXT command creates text by “processing” the words
in paragraph form; the width of the paragraph is determined by
the user-specified rectangular boundary.
Multiline Text tab
Style panel, Formatting panel, Paragraph panel and Insert panel
The Field dialog box shown with Field category “All” and Field
“Author” selected
Control Character Sequences for Drawing Special Characters and
Symbols
Text Editor shortcut menu
Edit text
The DDEDIT command allows to edit text.
If a text string is selected created by means of a TEXT command,
AutoCAD displays the Edit Text dialog box to edit the selected text and
if text string is selected created by means of the MTEXT command,
AutoCAD displays the Multiline Text Editor dialog box with the
selected text to edit.
Find & Replace
The FIND command is used to find a string of specified text and
replace it with another string of specified text.
Find & Replace dialog box
Justify Text
The JUSTIFYTEXT command change the justification point
of a text string without having to change its location.
The available justification includes: Align, Fit, Center,
Middle, Right, Top: Left-Center-Right, Middle: Left-CenterRight and Bottom: Left-Center-Right.
Spell Check
The SPELL command is used to correct the spelling of text objects
created with the TEXT or MTEXT command.
Creating and Modifying Text Styles
The STYLE command allows to modify or create a new text style that
determines how text characters and symbols appear, other than
adjusting the usual height, slant, and angle of rotation.
The Style option under the TEXT or MTEXT command allows to
choose a specific style from the styles available.
Three things to consider in creating a style: Specify a name for the
text style, select a font and specify how AutoCAD treats general
physical properties of the characters (height, width-to-height ratio,
obliquing angle, backwards, upside-down, and orientation), regardless
of the font that is selected.
Invoke the Text Style command:
Examples of Backward and Upside-down text
Example of vertically oriented text
Example of oblique angle settings applied to a text string
Creating and Modifying Tables
AutoCAD’s TABLE command makes it easy to create tables that
contain text in the row-and-column format customarily found on
drawings for listing revisions, finish schedules, specifications, and
other structured textual information. A combination of table
characteristics such as row and column sizes, border lineweights, text
alignments and associated text styles, and colors can be saved in a
Table Style with a specified name to be recalled and applied to tables
when required.
Creating a Table
Insert Table dialog box:
CREATING AND MODIFYING TABLE STYLES
The TABLESTYLE command is used to create a new table style or
modify an existing one. The appearance of the table is controlled by
its table style. The table style can specify a different justification and
appearance for the text and gridlines for the title, column heads, and
data.
Table Style dialog box
New Table Style dialog box, in which you define the new style
properties. There are three tabs to choose from: General, Text, and
Borders. Options on each tab set the appearance of the data cells, the
column heads, or the table title. The dialog box initially displays the
properties of the table style that you selected as the Start With style.
CREATING OBJECTS FROM EXISTING OBJECTS
AutoCAD not only allows to draw objects easily, but also allows to
create additional objects from existing objects.
This section discusses six important commands that will make your job
easier:
Copy
Array
Offset
Mirror
Fillet
Chamfer
Copying Objects
The COPY command places copies of the selected objects at the
specified displacement, leaving the original objects intact.
The copies are oriented and scaled the same as the original.
If necessary, you can make multiple copies of selected objects. Each
resulting copy is completely independent of the original and can be
edited and manipulated like any other object.
Example in using the COPY command
Creating a Pattern Of Copies
The ARRAY command is used to make multiple copies of
selected objects in either rectangular or polar arrays (patterns)
or along a selected path.
Rectangular array creates a pattern of multiple copies in rows and
columns. By default, AutoCAD creates a rectangular pattern of 3
rows and 3 columns.
Selection of the grip (blue box) of the Base Point (on the source
object), AutoCAD allows you to reposition the array to a new
location.
Selection of the grip of the last row and first column [Figure (a)], AutoCAD
allows you to add additional rows; and selection of the grip of the first row
and last column [Figure (b)], AutoCAD allows you to add additional
columns.
Figure (a)
Figure (b)
To increase the spacing between the columns, select the grip of the first
row and second column [Figure (a)] and drag in the direction you want to
increase the spacing.
To increase the spacing between the rows, select the grip of the second row
and first column [Figure (b)] and drag in the direction you want to increase
the spacing.
Figure (a)
Figure (b)
To increase both number of rows and columns, select the grip of the last
row and last column and drag in the direction you want to increase the rows
and columns.
Polar array creates multiple copies in a circular pattern by specifying
the angular intervals, the number of copies, the angle that the group
covers, and whether or not the objects maintains their orientation as
they are arrayed. By default, AutoCAD creates a polar pattern of 6
additional copies of the selected object.
By selecting the grip (blue box) of the Base Point (on the source
object) [Figure in (a)], AutoCAD allows you to change the array
radius.
By selecting the grip located on one of the arrayed items [Figure (b)],
AutoCAD allows you to change the angle between the items.
By selecting the grip of the center point of the array, AutoCAD allows
you to reposition the array.
Figure (a)
Figure (b)
In the Path array, AutoCAD creates multiple copies of the
selected object(s) along a selected path such as a polyline,
circle or rectangle. You can specify whether the objects
maintain their orientation or are aligned with the path as they
are copied.
Whenever an array object is selected, AutoCAD displays an
editing ribbon with panels for editing the selected array. You
can make the necessary changes to the pattern of the selected
array.
Creating Parallel Lines, Parallel Curves, and Concentric Circles
The OFFSET command creates parallel lines, parallel curves, and
concentric circles relative to existing objects.
Special precautions must be taken when using the OFFSET command
to prevent unpredictable results from occurring when using the
command on arbitrary curve/line combinations in polylines.
Valid objects include the line, spline curve, arc, circle, and 2D
polyline. If you try to select another type of object, such as text,
you will not be able to select the object. The object selected for
offsetting must be in a plane parallel to the current coordinate
system.
Creating a Mirror Copy Of Objects
The MIRROR command creates a copy of selected objects in
reverse, that is, mirrored about a specified line.
Text objects are mirrored relative to other objects within the selection
group. But text will or will not retain its original orientation, depending
on the setting of the system variable called MIRRTEXT. If the value of
MIRRTEXT is set to 1, then text items in the selected group will have
their orientations and location mirrored. If MIRRTEXT is set to 0
(zero), then the text strings in the group will have their locations
mirrored, but the individual text strings will retain their normal, left-toright, character appearance.
Creating a Fillet Between Two Objects
The FILLET command fillets (rounds) the intersecting ends of two
arcs, circles, lines, elliptical arcs, polylines, rays, xlines, or splines
with an arc of a specified radius.
If the TRIMMODE system variable is set to 1 (default), then the
FILLET command trims the intersecting lines to the endpoints of
the fillet arc.
If TRIMMODE is set to 0 (zero), then the FILLET command
leaves the intersecting lines at the endpoints of the fillet arc.
AutoCAD allows you to make additional pairs of objects to be filleted
without exiting the FILLET command by choosing Multiple option.
Creating a Chamber Between Two Objects
The CHAMFER command allows you to draw an angled corner
between two lines. The size of the chamfer is determined by the
settings of the first and the second chamfer distances.
If the TRIMMODE system variable is set to 1 (default), then the
CHAMFER command trims the intersecting lines to the endpoints
of the chamfer line.
If TRIMMODE is set to 0 (zero), then the CHAMFER command
leaves the intersecting lines at the end-points of the chamfer line.
AutoCAD allows you to make additional pairs of objects to be
filleted without exiting the CHAMEFR command by choosing
Multiple option.
MODIFYING OBJECTS
AutoCAD not only allows to draw objects easily, but also allows to
modify objects. This section discusses four important commands that
will make your job easier:
Move
Trim
Break
Extend
Moving Objects
The MOVE command moves one or more objects from their
present location to a new one without changing orientation or
size.
Trimming Objects
The TRIM command is used to trim the portion of the object(s) that is
drawn past a cutting edge or from an implied intersection defined by
other objects.
Objects that can be trimmed include lines, arcs, elliptical arcs, circles,
2D and 3D polylines, xlines, rays, and splines. Valid cutting edge
objects include lines, arcs, circles, ellipses, 2D and 3D polylines,
floating viewports, xlines, rays, regions, splines, and text.
Erasing Parts of Objects
The BREAK command is used to remove parts of objects or to split an
object in two parts, and it can be used on lines, xlines, rays, arcs,
circles, ellipses, splines, donuts, traces, and 2D and 3D polylines.
Extending Objects to meet Another Object
The EXTEND command is used to change one or both endpoints of
selected lines, arcs, elliptical arcs, open 2D and 3D polylines, and rays
to extend to lines, arcs, elliptical arcs, circles, ellipses, 2D and 3D
polylines, rays, xlines, regions, splines, text string, or floating
viewports.