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C H A P T E R 22Fundamentals of 2D

Construction


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Engineering Graphics with AutoCAD 2011, 1/eJames Bethune

2011 Pearson Higher Education,Upper Saddle River, NJ 07458. All Rights Reserved.2

LINERANDOM POINTS

The Line command is

used to draw straight

lines between

two defined points

The Line tool on

the Draw panel


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To randomly select points1. Select the Linetool on the Draw

panel under theHome tab.

Command: _lineSpecify first point:

2. Place the cursor

randomly on thedrawing screen

and press the left

mouse button.

Specify next point

or [Undo]:

3. Randomly pickanother point on the

screen.Specify next point or

[Undo]:


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To exit a command sequence

Press the key, which will

return you to a command prompt.

Note:

The key allows you to exitalmost all Auto-CAD commands.

The Line command may be

reactivated by pressing the right

mouse button immediately afterselecting the Enter option. A dialog

box will appear


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ERASE

There are two ways to

erase lines: select

individual lines or

window a group of lines.

The Erase tool is located

on the Modify panel

under the Home tab


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To Erase individual lines1. Select the Erase

tool on the Modifypanel.

Command: _erase

Select objects:

select cursor (pickbox).

2. Select the two open

lines by placing the

rectangular cursor

on each line, one at

a time, and pressing

the left mouse

button

Select objects: 1 foundSelect objects:

3. Press the right mouse

button or the Enter

key to complete the

Erase sequence.


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To erase a group of lines

1. Select the Erase tool.Command: _erase

Select objects:

2. Place the rectangular selectcursor above and to

the left of the lines to be erased andpress the left mouse button.

3. Move the mouse, and a shaded

window will drag from the selectedfirst point.

4. When all the lines to be erased

are completely within the window,

press the left mouse button.

Once selected, elements"will change color on the screen.

All elements completely within the window will be erased.


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LINESNAP POINTS

Lines can be drawn using calibrated snap spacing. This

technique is similar to drawing points randomly, but because

the cursor is limited to specific points, the length of lines can

be determined accurately.


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LINECOORDINATE VALUES

AutoCAD will also accept locational inputs, the start andend points of a line, in terms of X,Y coordinate values. The 0,0

origin is located in the lower left corner of the drawing screen.

Lines can be drawnusing coordinate points.


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LINEDYNAMIC INPUTS

The Dynamic Input command allows both angular anddistance values to be added to a drawing using screen prompts .

The Dynamic Inputs dialog box is used to control the Pointer Input,Dimension Input, and Dynamic Prompts aspects of dynamic input

(See Next Slide).


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Dynamic Input settings

The Dynamic

Inputs dialog box

is used to controlthe Pointer Input,

Dimension Input,

and Dynamic

Prompts aspects of

dynamic input


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CONSTRUCTION LINE

The Construction Line command is used to draw lines of infinite

length. Construction lines are very helpful during the initial layout of

a drawing. They can be trimmed during the creation of the drawing

as needed.

Construction line


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Other Construction Line commands:

Construction lines drawnusing the Horizontal, Vertical,

and Angular options

The lines shown below were created using the Hor (horizontal),Ver (vertical), and Ang (angular) options.


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Construction Line command: Offset

The Offset option allows you to draw a line parallel to an existingline, regardless of the lines orientation, at a redefined distance.

Construction lines drawn

0.5 apart using theOffset option.

Press the right mouse button to end the Offset command sequence

and return a command prompt to the command prompt line


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CIRCLEThe Circle tool is on the Draw panel. Circles may be defined by a center point and

either a radius or diameter; by two or three points on the diameter; or by the tangents totwo existing lines or arcs and a radius value.

Each of these commands has a separate tool on the Draw panel that is a flyout from the

Circle tool


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CIRCLE Creation Types

Circle Radius

Circle Diameter

Circle 2 points

Circle 3 points

Circle Diameter

Tangent Tangent Radius

* See of you can Name the Circle Creation Types


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CIRCLE CENTERLINES

It is standard

drawing

convention to

include

centerlines

with all circles.

Circles usuallyrepresent holes.

The circles

center point is

used to locate

the circle and,

during

manufacture,serves as the

location point for

a drill.

The Center Mark option found on the Dimensions panel of the

Annotate tab.


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The Center Mark tool

Select the Symbolsand Arrows tab,

then the Centermarks Line option.


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POLYLINEApolyline is a line made from a series of individual,connected line segments that act as a single entity

Polyline are used to

generate curves and

splines and can beused in three-

dimensional

applications to produce

solid objects.


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Polyline Arc

A Polyline drawnusing the Arcoption

The Polyline Arc is a single entity.

Select the Polyline tool

from the Draw panel.


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To draw different line thicknesses

The Width option is used to define the width of a line. The

Halfwidth option is used to define half the width of a line.


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SPLINE

A closed spline

A spline is a curved line created through a series of

predefined points. If the curve forms an enclosed area, it iscalled a closed spline


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ELLIPSE

Click the Ellipse Axis, End tool on

the Draw panel.


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Ellipse Arc

An ellipse may also be defined in terms of its angle of rotationabout the major axis. An ellipse with 0 rotation is a circle, an

ellipse of constant radius. An ellipse with 90 rotation is a straight

line, an end view of an ellipse


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RECTANGLE

The Rectangle command is used to draw rectangles. Therectangles generated are blocks, that is, they are consideredto

be one entity, not four straight lines.


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POLYGONApolygon is a closed

figure bounded bystraight lines.The Polygon

command will drawonly regular

polygons, in

which all sides areequal


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POINT

The Point command is used to draw points on a drawing.The default setting for a points shape is a small dot, the kind used

to display background grids. Other point shapes are available.


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TEXT

Text is added to a drawing using the Multiline Text tool found onthe Annotation panel. The Annotation panel is located under the

Home tab.

The Multiline Text command is used to enter text.First, the area in which the text is to be entered is defined. Text is typed

into the dialog box.


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The Text Editor

The Multiline Text tool is also available on the Text panel of theAnnotate tab.

The Text Editor panel is used to change the text height, color, fontstyle, and text justification.


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Justify Text

AutoCAD will justify text to the left unless otherwise specified.


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The symbol options

AutoCAD has three symbol commands:%%C

%%P

%%D

A symbol will initally appear in the %% form in the Text Editor dialogbox but will change to the equivalent symbol when the text is

transferred to the drawing.

Symbols may also be created using the Windows Character

ALT 0216

ALT 0177ALT 0176


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MOVE

The Move command is used to move a line or object to a newlocation on the drawing.

Any point may beselected. Snap

points are usually

used as base pointsbecause they candefine precise

displacement

distances andaccurate new

locations.


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The Copy command

The Copy commandmaintains the original

object in its originallocation, then creates a

copy that can be moved toa new location.

The Copy command is used to make anexact copy ofan existing line or object. The

Copy command can also be used to createmore than one copy without reactivating the

Command.


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OFFSETThe process may be repeated by

double-clicking the right mouse

button and selecting the Repeat

Offset option.

Mirror

Any line may be used as a mirror line,

including lines within the object

The Mirror command is very

useful when drawing symmetricalobjects. Only half of the object need be

drawn. The second half can be created

using the Mirror command.


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ARRAY

Objects may be arrayed using either the Rectangularor the Polaroption.


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ROTATE

The Rotate tool is used to rotate an object about a specifiedbase point.


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TRIM

The Trim tool isused to cut away

excessively long

lines.

Trim is a very

important AutoCAD

command and is

used frequently. Cutting Edge

Trimmed area


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EXTEND & BREAK

The Extend command allowsgiven lines to be extended

to new lengths

The Break command is used toremove portions of an object. It is

similar to the Trim command butdoes not require cutting edges


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CHAMFER

A chamfer is a

straight-line

corner cut, usually

cut at

45. Other angles

may be used.


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FILLET

The Fillet command islocation sensitive. The finalshape of the fillet will dependon the location of yourselection points. Here are

four examples of fillets drawnfrom the same initial arc linesetup.


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TABLEThe Table command is used to create tables such as the one

shown below. Tables are used on drawings to define multiple holedimensions, to define coordinate data, and to create parts lists,

among other uses.


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Creating tablesClick the Table command tool on the annotation Panel.

The Insert Table dialog box will appear

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