AutoCAD Lab Manual

CONTENTS

Chapter 1 Getting Started 1 Chapter 2 Setting up the Drawing Environment 13

Drawing Aids Setting Drawing Units Setting Grid Limits Function Keys Object Snap

Chapter 3 Using Coordinate System 27 Chapter 4 Drawing Objects 33 Chapter 5 Modifying Objects 47

Objection selection methods Modify Commands

Chapter 6 Adding Dimensions and Text 69 Solved Exercises 81

Exercise 1 Exercise 2 Exercise 3 Exercise 4

Exercises Problems 111

Chapter 7 Working with 3D 115 Exercise Problems 125

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AUTOCAD 2002 Introduction AutoCAD is an outstanding tool for learning the basics of Engineering

Drawing. Featuring Problem solving, step by step tutorials it takes the user

from one view engineering drawing to geometric constructions, multi-view

projections, 3D modeling and solid modeling. Each tutorial follows a traditional

engineering drawing techniques and methods while showing how to utilize the

features and benefits of AutoCAD to achieve professional results.

AutoCAD is the most widely used design and drafting software in the world.

AutoCAD 2002 provides you with the capability to create complex and

accurate drawings. Its position as the industry standard makes it an essential

tool for anyone preparing for a career in engineering, design, or technology.

Because it is the industry standard, AutoCAD is the ideal cornerstone for your

design and drafting skill set. With knowledge of AutoCAD, you will find it easy

to add any number of a wide range of applications to create a complete

design environment suited to your needs.

AutoCAD 2002 interface is more design-centric and less command-centric,

making the software more transparent in design process.

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Starting AutoCAD

From the Start Menu choose Programs. Then choose AutoCAD2002 from the

menu

OR

you can double click the icon available on the desktop

When you start AutoCAD the AutoCAD Today 2002 dialog box is displayed.

The dialog box provides you with two ways to start a drawing. You can

Open Drawings : It enables you to Open a Drawing from a list of four

most recently opened drawings. It also displays a Browse button to

choose another file.

Create Drawings : Create Drawings Tab allows you to create your

drawings in three ways

AutoCAD 2002.lnk

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Start from the scratch : Opens a drawing based on the measurement

system you choose

English – feet and inches

Metric – millimeters

Template : Opens a drawing based on a template you select from a list.

The list displays template files that exist in the drawing template file

location as specified in the options dialog box.

Wizards : Opens a drawing that you set up using either the Quick

Setup wizard or the Advanced Setup Wizard.

STARTING DRAWINGS FROM THE SCRATCH

Starting a drawing from the scratch is a quick way to begin a new drawing.

When you select this drawing startup method, you can select one of the

two measurement systems on which to base the new drawing.

English : Creates a drawing based on Feet and Inches measurement

system. The default drawing boundary, called drawing limits is 12 x 9

inches.

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Metric : Creates a drawing based on metric measurement system. The

default drawing boundary is 429 x 297 millimeters.

To start a new drawing using Start from Scratch (New Drawing)

1. In the AutoCAD2002 Today dialog box select the Create Drawings

Tab. In the ‘Select how to Begin’ window choose Start from Scratch. ( If

AutoCAD is already started, from the File menu, choose New, then

select Create Drawings Tab, in the window Select How to Begin,

choose Start from the Scratch)

2. Select English or Metric as required, the drawing opens based on the

measurement system selected

Command line : NEW

OPEN EXISTING DRAWINGS

To open an existing AutoCAD drawing, you can select Open Drawings tab

in the AutoCAD2002 dialog box or, if AutoCAD is already started, choose

Open from the File Menu..

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To open a drawing

1. In the AutoCAD2002 Today dialog box , choose Open Drawings. It

displays four recently used drawings or if you want to select a drawing

other than these, choose Browse.

2. In the Select file dialog box, select the required file and choose Open.

Command line : OPEN

UNDERSTANDING THE AUTOCAD WINDOW

When you start AutoCAD, the AutoCAD window opens. The window is the

design space. It contains elements that you use to create your designs and to

receive information about them. The main parts of the AutoCAD window are

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Menu Bar It contains the default AutoCAD menus. Menus are

defined by menu files that you can modify or design on

your own. The default menu file is acad.mnu. Menu bar

contains the Pull Down menus such as File, Edit, View,

Insert, Format etc.

Standard Toolbar It contains Microsoft Office standard buttons such as

New, Open, Save, Print etc and frequently used buttons

such as Redraw, Undo, Zoom etc. The lower right corner

of the buttons have flyouts which displays the function of

each button.

Object Properties It enables you to set the properties of the objects such as

Toolbar Color, Linetype and Line-Weight and also manages

Layers.

Draw and Modify Provides access to common Draw and Modify

Toolbar commands. The Draw and Modify toolbars are displayed

when you start AutoCAD. These toolbars are docked on

the left side of the window. They are also called as

Floating Toolbars as they can be easily moved and

placed anywhere on the screen. You can turn the

toolbars ON or OFF. To turn On or OFF any toolbar Right

Click on any available toolbar, it displays a list of toolbars,

select (click on) the desired toolbar you want to display or

close.

Drawing Area It displays the drawing. The drawing area size varies,

depending on the size of the AutoCAD window and other

elements such as toolbars and dialog boxes that are

displayed.

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Crosshairs Identifies pick and drawing points within the drawing area.

You can use the crosshairs, which are controlled by your

pointing device (such as mouse), to locate points and

select and draw objects. It also displays the current X, Y

and Z co-ordinate values as you move it.

User Coordinate It shows the orientation of the drawing. AutoCAD

drawings

System (UCS) are superimposed on an invisible grid, or coordinate

Icon system, based on X, Y and (for 3D) Z coordinates.

AutoCAD has a fixed world coordinate system (WCS) and

a movable user coordinate system (UCS).

Model / Layout It enables you to switch your drawing between model

Tabs (drawing) space and paper (layout) space. You create

your designs in the model space, and then create layouts

to plot or print your drawings in paper space.

Command Window Displays prompts and messages. In AutoCAD you can

give the command in one of the Three ways

Choose an item from the menu or a shortcut menu

Click a button on a toolbar

Enter the command on the Command Line

Whichever method you use to give the command,

AutoCAD displays command prompts and the command

history in the command window. It is a good practice to

have an eye on the command window as the prompts

displayed will enable you to know what exactly is

required. It also displays error messages which will

enable you to rectify the error.

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Status Bar Displays the cursor coordinates in the lower left corner.

The status bar also contains buttons that can be used to

turn on/off the common drawing aids. These include

Snap, Grid, Ortho, Polar, Osnap etc.

USING POINTING DEVICES

The Drawings can be controlled in AutoCAD using a pointing device such as a

standard mouse, an IntelliMouse or a digitizing tablet. The points can be

specified either by clicking the pointing device or by entering coordinates on

the command line.

MOUSE

The options from menus and toolbars can be selected by clicking them with

the mouse. Mouse can also be used to draw or to select objects on the

screen. With a two button mouse, the left button is a pick button used to

specify points on the screen. The right button either displays a shortcut menu

or is equivalent to pressing Enter. With a three button mouse, the middle

button either activates real-time panning or displays the Object Snap shortcut

menu.

INTELLIMOUSE

The IntelliMouse is a two button mouse with a small wheel between the

buttons. The left and right button behave in the same way as in a standard

mouse. The wheel can be used to zoom and pan in your drawing without

using any AutoCAD command.

Using the Intel l iMouse with AutoCAD Zoom in or out Rotate the wheel forward to zoom in,

backward to zoom out .

Zoom to drawing extents Double-click the wheel button

Pan Press the wheel button and drag the mouse

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SAVING DRAWINGS

When you are working on a drawing, you should save it frequently to avoid

loss of work.

To save a drawing.

1. From the file menu choose Save

If you have previously saved and named the drawing, AutoCAD saves

any subsequent changes in the same drawing.

Save Drawing As dialog box is displayed.

2. In the dialog box under File Name, enter the name of the drawing

3. Choose save

Command Line : SAVE

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CLOSING DRAWINGS The close command closes the active drawing (in case you are working with

multiple drawings).

1. Drawings can be Closed by clicking on the close button in the upper-

right corner of the drawing or

2. From the File Menu choose Close

EXITING AUTOCAD

From the File menu choose Exit

Command Line : QUIT

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DRAWING AIDS Introduction

Drawing with AutoCAD is just like drawing on a drawing board. Most new

comers to Computer Aided Design assume that they will need to learn how to

draw all over again. In fact, many of the drawing aids that AutoCAD provides

are analogous to traditional drafting tools. Just as you have a parallel motion

and set squares to help you draw horizontal and vertical lines on a drawing

board, AutoCAD has similar drawing aids which can help you to draw

horizontal and vertical lines on a computer. This means that in many respects,

the drawing techniques are very similar. If you ever get stuck, think how you

would complete a task on a drawing board and then look for a similar way to

do it with AutoCAD.

The Drawing Grid

The Grid can be turned ON/OFF by pressing the button on the status bar.

The drawing grid is a regular pattern of dots displayed on the screen which

acts as a visual aid, it is the equivalent of having a sheet of graph paper

behind your drawing on a drawing board. You can control the grid spacing, so

it can give you a general idea about the size of drawn objects. It can also be

used to define the extent of your drawing. Grid Spacing set to 10 units Grid Spacing set to 5 units

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Setting the Grid Spacing

1. From the Tools Menu select Drafting Settings… The Drafting

Settings tool box is displayed

2. Click on the "Snap and Grid" tab of the Drafting Settings dialog box.

3. Enter the value of the Grid X spacing in units

4. To use the same value for the Grid Y spacing, press Enter.

Otherwise enter a new value for Grid Y spacing.

5. Choose OK

Shortcut Menu

Grid settings can be changed by right-clicking the Grid

button on the status bar and selecting Settings… from

the menu. Drafting Settings dialog box is displayed ,

which enables you to change the value of the Grid.

Enter the value of the Grid spacing press OK.

Command Line : GRID

Specify grid spacing(X) or [ON/OFF/Snap/Aspect] <10.000>: (enter grid spacing)

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The Snap option allows you to automatically set the grid spacing to the

current snap spacing. You can also change the aspect ration of the grid. By

default, the X and Y spacing of the Grid are the same, resulting in a regular

square matrix of grid points. But if you need a grid with different X and Y you

can use the "Aspect" option. Snap Mode

Snap mode takes AutoCAD one step further than the drawing board. With

Snap mode turned on AutoCAD only allows you to pick points which lie on a

regular grid. The Snap grid is completely independent of the display grid.

However, the Grid spacing and Snap spacing are usually set to the same

value to avoid confusion. When Snap mode is turned on and the Grid is

displayed, the Snap and Grid spacing are the same and the crosshairs will

jump from one grid point to another as you move across the screen. This

makes it very easy to draw objects which have a regular shape. The Snap

command is used to set the snap spacing and to toggle Snap mode.

The Snap can be turned ON/OFF by pressing the button on the status bar. Setting the Snap Spacing

1. From the Tools Menu select Drafting Settings… The Drafting

Settings tool box is displayed

2. Click on the "Snap and Grid" tab of the Drafting Settings dialog box.

3. Enter the value of the Snap X spacing in units

4. To use the same value for the Snap Y spacing, press Enter.

Otherwise enter a new value for Snap Y spacing.

5. Choose OK

Shortcut Menu

Snap settings can be changed by right-clicking the Snap

button on the status bar and selecting Settings… from the

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menu. Drafting Settings dialog box is displayed , which enables you to change

the value of the Snap. Enter the value of the Snap spacing press OK.

Command Line: SNAP Specify snap spacing or [ON/OFF/Aspect/Rotate/Style/Type] <10.0000>: (enter the required snap spacing in drawing units)

The "Aspect" option can be used to vary the horizontal and vertical snap

spacing independently. "Rotate" is used to set the snap grid to any angle.

You can also set the snap style to either Isometric or Standard (the default)

using the "Style" option. The Standard style is used for almost all drawing

situations including detail drawings in Orthographic Projection. The Isometric

style is specifically to aid the creation of drawings in Isometric Projection

Ortho Mode

Ortho is short for orthogonal, which means either vertical or horizontal. Like

the other options on the status bar, Ortho is not really a command, it is a

drawing mode which can either be turned on or off.

Click on the button on the status bar. The appearance of the

button tells you whether Ortho is currently turned on or turned off.

When Ortho is turned on, the ORTHO button appears pressed in. You

can see how this appears by looking at the status bar illustration below.

In the illustration, Ortho is turned on but Grid and Snap are turned off.

Command Line : ORTHO

Enter mode [ON/OFF] <OFF>: (type ON or OFF)

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Setting Drawing Units

Every object that is drawn in AutoCAD is measured in units. You determine

the value of the units within AutoCAD before you draw. For example, in one

drawing, a unit might equal one millimeter, while in another drawing, a unit

might equal an inch. In AutoCAD we can set the Unit type and number of

decimal places for object length and angle. Drawing Unit settings control how

AutoCAD interprets the coordinate and angle entries and displays coordinates

and units in the drawing.

To format Drawing Units

1. From the Format menu choose Units. The Drawing Units dialog box is

displayed

2. Under Length, select a unit type and precision (number of decimal

places)

3. Under Angle, select an angle type and precision

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4. To specify an angle direction, choose Direction, and then select the

base angle in the Direction Control dialog box

The angle direction controls the point from which AutoCAD measures

angles and the direction in which they are measured. The default is 0

degrees on the right side of the figure, measured anticlockwise.

5. Choose OK to exit each dialog box

Command Line : UNITS The dialog box is displayed and the units can be changed in the same way as

described above.

Setting Grid Limits

Drawing Limits is used to define the extent of the grid display and to toggle

Limits mode which can be used to define the extent of your drawing. The grid

is displayed within a rectangle defined by two pick points or co-ordinates.

To set Grid limits Command Line : LIMITS Reset Model space limits: Specify lower left corner or [ON/OFF] <0.0000,0.0000>: (pick point, enter co-ordinates or to accept the default value)

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Specify upper right corner <420.0000,297.0000>: (pick point, enter co-ordinates or to accept the default value)

The lower left corner corresponds to the lower left corner of the drawing area

and the upper right corner of the limits corresponds to the upper right corner

of the drawing area.

Drawing Limits can also be used to turn Limits mode on or off. Limits mode

can be used to control where objects can and cannot be drawn. Limits is

turned off by default which means that there is no restriction as to where

points can be picked and objects drawn. When Limits is on, AutoCAD will not

allow points to be picked or co-ordinates entered at the command line which

fall outside of the specified drawing limits. If you try to pick a point outside the

drawing limits when Limits mode is turned on, AutoCAD reports to the

command line:

**Outside limits

Limits mode is useful if you know the extent of your plotted drawing sheet and

you want to prevent objects being drawn outside of this area. However,

Drawing Limits is most commonly used simply to control the extent of the

Grid.

To Change the Grid limits from the Format menu, choose Drawing

Limits and the limits can be changed in the same way as discussed

above.

Note : After setting the grid limits, from the View menu, choose Zoom – All.

The grid shows the area defined by the limits.

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The Function Keys

Many of the modes described above can be controlled quickly using the

keyboard function keys. In most cases this is quicker than using a pull-down

or the command line. The function keys are arranged along the top of your

keyboard. AutoCAD uses function keys F1 to F11. The use function keys is

described below.

Function key Description

F1 AutoCAD Help

F2 Used to toggle (turn on and off) the AutoCAD text window

F3 Object Snaps ON/OFF

F4 Tablet mode ON/OFF

F5 cycles through the Isoplanes, this only has an effect if

"Isometric Snap/Grid" mode is on. The options are Left, Top

and Right

F6 Coordinate display ON/OFF

F7 Grid ON/OFF

F8 Ortho ON/OFF

F9 Snap ON/OFF

F10 Polar Tracking ON/OFF

F11 Object snap tracking ON/OFF

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Object Snap

The Object Snaps (Osnaps for short) are drawing aids which are used in

conjunction with other commands to help you draw accurately. Osnaps allow

you to snap onto a specific object location when you are picking a point. For

example, using Osnaps you can accurately pick the end point of a line or the

center of a circle.

Object Snap Toolbar Command

Line

snaps to

Endpoint END Endpoint of the object

Midpoint MID Midpoint of the object

Intersection INT Intersection of objects

Apparent

Intersection

APP Apparent intersection of objects

Extension EXT Object extension paths

Center CEN Center points of circles, arcs..

Quadrant QUA Closest quadrant of circles or arcs

Tangent TAN Point on a circle or arc, when

connected to last point , forms a line

tangent to the object

Perpendicular PER Object points forming perpendicular

alignment

Parallel PAR Point on an alignment path that is

parallel to the selected object

Insert INS Insertion point

Node NOD objects drawn with Point command

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To use Object Snaps

1. Running object snaps can be switched ON/OFF by clicking on the

button on the status bar.

2. To set the object snaps, right click on the button on the status

bar and select settings or Tools Drafting Settings…, select on the

object snap tab and a Drafting settings dialogue box is displayed.

Select the object snaps required and choose OK

Object Snap Description

The object snap buttons are located on the objects snap flyout on the

standard toolbar. Some of the important and most frequently used object

snaps are described below:

1. Endpoint :

The Endpoint Osnap snaps to the end points of

lines and arcs and to polyline vertices.

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2. Midpoint : The Midpoint Osnap snaps to the mid pionts of

lines and arcs and to the mid point of polyline

segments.

3. Intersection :

The Intersection Osnap snaps to the physical

intersection of any two drawing objects (i.e.

where lines, arcs or circles etc. cross each other)

and to Polyline vertices.

4. Center :

The Center Osnap snaps to the centre of a

circle, arc or polyline arc segment. The cursor

must pass over the circumference of the circle

or the arc so that the centre can be found.

5. Quadrant :

The Quadrant Osnap snaps to one of the four

circle quadrant points located at north, south,

east and west or 90, 270, 0 and 180 degrees

respectively.

6. Tangent :

The Tangent Osnap snaps to a tangent point on

a circle. This osnap works in two ways. You can

either draw a line from a point to the tangent

point or you can draw a line from a tangent point

or you can draw a line which is tangent to two

circles, arcs etc..

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7. Perpendicular :

The Perpendicular Osnap snaps to a point

which forms a perpendicular with the selected

object. As with the Tangent Osnap,

Perpendicular can be used to draw a line to a

perpendicular point or from a perpendicular

point.

8. Parallel :

The Parallel Osnap is used to draw a line

parallel to any other line in your drawing. To

draw a parallel line, first start the Line

command, specify the first point when

prompted and then start the Parallel Osnap.

Hover the cursor over an existing line until you see the Parallel snap

marker. Now, move the cursor close to a parallel position and a dotted

line will appear, indicating the parallel. You can now pick the second

point of your line.

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Using Co-ordinates Introduction

A good understanding of how co-ordinates

work in AutoCAD is absolutely crucial if

you are to make the best use of the

program.

Co-ordinates fall into two types, namely

Cartesian and Polar. A basic

understanding of these co-ordinate types

will help you to use AutoCAD to construct

drawings more easily. They can be further

be classified as either Absolute or

Relative.

Cartesian Co-ordinates

The Cartesian co-ordinate system is the standard co-ordinate system. The

position of a point can be described by its distance from two axes, X and Y.

This results in a simple point description using two numbers separated by a

comma e.g. 34,45

In the example given to the right point

described lies 34.897 drawing units to

the right of the Y axis and 45.473

drawing units above the X axis. The

first value (34.897) is known as the X

co-ordinate because it's value is

measured along the X axis. The

second value is known as the Y co-

ordinate because it's value is

measured along the Y axis. The X and

Y axes are two lines of infinite length which intersect at the origin point. The

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co-ordinate value of the origin point is always 0,0. When viewed in plan the X

and Y axes are always perpendicular to one another with the X axis in a

horizontal position and the Y axis in a vertical position. Normally we work in

the positive quadrant. Although this is not essential for AutoCAD to operate, it

does tend to make life easier because we don't need to worry about negative

numbers.

Polar Co-ordinates

Polar co-ordinates achieve the same result i.e. the description of the position

of a point. The main difference is that polar co-ordinates use distance and

angle to describe the position of a point rather than the X and Y coordinates in

the Cartesian system. The distance and angle measurements are made

relative to an origin. This results in a point description which looks like this

24<30 where the first value is the distance (in drawing units) and the second

is the angle. Notice that the separator in the case of polar co-ordinates is the

"less than" mathematical symbol.

AutoCAD angles start along the

positive portion of the X axis and

increase in an anti-clockwise direction.

You can specify negative angles if you

need to define an angle in a clockwise

direction although this is not really

necessary because angles are

circular, hence an angular value of -30

degrees will give the same result as

an angular value of 330 degrees as

there are 360 degrees in a full circle. The figure on the right illustrates an

example of a line of length 35.8 drawn at an angle of 60 degrees.

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The UCS Icon

In the bottom left hand corner of the AutoCAD

drawing window you will see a symbol like the one

shown on the left. This is called the UCS (User Co-

ordinate System) icon and it is there to remind you

which is the X axis and which is the Y axis. The

empty box at the intersection of the X and Y axes is

there to remind you that you are using "World" co-

ordinates and that the UCS icon is not positioned over the true origin of the

current co-ordinate system, probably because it is off screen.

Absolute & Relative Co-ordinates

Both Cartesian and polar co-ordinates can be divided into two types, absolute

and relative. The distinction is quite simple, absolute co-ordinates relate to the

X and Y axes and the origin of the current co-ordinate system, whilst relative

co-ordinates relate to the current pick point. When you are specifying co-

ordinates you need to tell AutoCAD which type you want. In the case of the

two examples above a relative Cartesian co-ordinate looks like this

@34.897,45.473 and a relative polar co-ordinate looks like this @34.897<30.

For example if you want to draw a line from point 20,10 to 40,30

1. In Absolute Cartesian Coordinate system you specify it as

From point : 20,10

To point : 40,30

2. In Relative Coordinate system you need to specify it as

From point : 20,10

To point :@ 20,20 (relative to previous point)

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Direct Distance Entry

Introduction

Direct distance entry is one of those AutoCAD features that is often

overlooked. This is rather unfortunate because it can be extremely useful and

an amazing time-saver. Basically, direct distance entry enables you to draw

an object, such as a line, by pointing in a particular direction with the cursor

and entering a distance at the command line.

To Draw a line using Direct Distance Entry For example, let as assume that we want to draw a horizontal line with a

length of 30 drawing units.

1. Start the Line command, Draw Line from the pull-down menu or

from the Draw toolbar.

2. When prompted, to specify the first point for the line, pick a point

somewhere on the left side of the drawing area

3. Move your cursor to the right (or in the direction you want the line) of

the first pick point. Hold your cursor in this position and simply enter 30

from the keyboard.

4. Press the Enter key, a line segment is drawn, 30 units long and in the

direction you were pointing.

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Drawing Objects The Draw commands can be used to create new objects such as lines and

circles. Most AutoCAD drawings are composed purely and simply from these

basic components. A good understanding of the Draw commands is

fundamental to the efficient use of AutoCAD.

This section covers the most frequently used Draw commands such as Line,

Polyline, Circle etc. As a newcomer to AutoCAD, you may wish to skip the

more advanced commands in order to properly master the basics. You can

always return back to these commands in the future when you are more

confident.

In common with most AutoCAD commands, the Draw commands can also be

given in THREE ways.

1. Command names or short-cuts can be entered at the Keyboard

Command line : LINE or L

2. Commands can be started from the Draw Pull-Down Menu

3. From the Draw Toolbar.

Note : In a pull down menu a small arrow like " " next to a

menu item means that the item leads to a sub-menu that may

contain other commands or command options. An ellipsis, "…"

after a menu item means that the item displays a dialogue box.

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Lines

Lines are probably the most simple of AutoCAD objects. Using the Line

command, a line can be drawn between any two points picked within the

drawing area. Lines are usually the first objects you will want to draw when

starting a new drawing because they can be used as "construction lines" upon

which the rest of your drawing will be based.

A line can be one segment or a series of segments, but each segment is a

separate line object. The line command can be used when you need to edit

individual segments.

The Line Command

Toolbar

Pull-down menu Draw Line

Command: Line (or) L

To Draw a Line

By Picking points on the screen With the Line command you can draw a simple line from

one point to another. When you pick the first point (P1) and

move the cross-hairs to the location of the second point

(P2) and pick the second point, the line is drawn from the

first point to the second point. Line objects have two ends

(the first point and the last point). You can continue picking

points and AutoCAD will draw a straight line between each

picked point and the previous point. Each line segment

drawn is a separate object and can be moved or erased as required. To end

this command, just hit the key (enter key) on the keyboard.

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Using Cartesian Coordinates

1. Select the command from the Toolbar or Draw Line

Command Sequence

Command : Line

Specify first point : 10,5 (or give any point) press

Specify next point : 20,30 press

Specify next point : enter the coordinates of the next

point or to complete the line

A line will be drawn between these two points

Using Polar Coordinate system

1. Select command from the Toolbar or Draw Line

Command Sequence

Command : Line

Specify first point : Specify value of a point press or pick a

point

Specify next point : @20<45

Specify next point : enter the length and angle of the

next line or to complete the

line

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Using Direct Distance Entry

1. Select the command from the Toolbar or Draw Line

Command Sequence

Command : Line

Specify first point : Specify value of a point press or pick a

point

Specify next point : 30, move the cursor in direction in which you

want the line

Specify next point : enter the length of the next line, move the cursor

in the direction of the desired line or press

enter to complete the line

Polylines

A polyline is a connected sequence of line or arc segments created as a

single object. Polyline command can be used when you need to edit all

segments at once, set width of individual segments, make segments taper

and close the polyline. In practice the Polyline command works in the same

way as the Line command allowing you to pick as many points as you like.

Again, just hit to end. As with the Line command, you also have the option

to automatically close a polyline end to end. To do this, type C to use the

close option instead of hitting . The example above shows a number of

polylines to give you an idea of the flexibility of this type of line.

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The Polyline Command

Toolbar

Pull-down menu Draw Polyline

Command: Pline (or) PL

To Draw a rectangle of 50 x 30

1. Select command from the toolbar (or) Draw Polyline

Command Sequence

Command : Pline

Specify start point: (pick P1)

Current line-width is 0.0000

Specify next point or [Arc/Halfwidth/Length/Undo/Width]: 50, move cursor

towards right press

Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: 30, move

cursor upwards press


cursor towards left press


cursor downwards press

(or C to close)

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Rectangle

The Rectangle command is used to draw a rectangle whose sides are vertical

and horizontal. The position and size of the rectangle are defined by picking

two diagonal corners. The rectangle isn't really an AutoCAD object at all. It is,

in fact, just a closed polyline which is automatically drawn for you. The

Rectangle command also has a number of options. Width works in the same

way as for the Polyline command. The corners of the rectangle can be

Chamfered and Filleted. The Elevation and Thickness commands are 3D

options.

The Rectangle Command

Toolbar

Pull-down Menu Draw Rectangle Command Rectangle (or) REC

Command Sequence

Command : Rectangle

Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: (pick P1)

Specify other corner point or [Dimensions]: (pick P2)

41

The Polygon Command

The Polygon command can be used to draw any regular polygon from 3 sides

up to 1024 sides. This command requires four inputs from the user, the

number of sides, a pick point for the center of the polygon, whether you want

the polygon inscribed or circumscribed and then a pick point which

determines both the radius of this imaginary circle and the orientation of the

polygon. The polygon command creates a closed polyline in the shape of the

required polygon.

This command also allows you to define the polygon by entering the length of

a side using the Edge option. You can also control the size of the polygon by

entering an exact radius for the circle.

To Draw a Polygon

Toolbar

Pull-down menu Draw Polygon

Command Polygon (or) POL

Command Sequence

Command : Polygon

Enter number of sides <4>: 5

Specify center of polygon or [Edge]: pick P1 or type E to define by edge

length

Enter an option [Inscribed in circle/Circumscribed about circle] <I>:

(to accept the inscribed default or type C for circumscribed)

Specify radius of circle: pick P2 or enter exact radius

42

Circle

Along with Line and Polyline, the Circle command is probably one of the most

frequently used. In common with the other commands in this section there are

a number of options that can help you construct just the circle you need. Most

of these options are self explanatory but in some cases it can be quite

confusing. The Circle command, for example, offers 6 ways to create a circle.

The Circle Command

Toolbar

Pull-down menu Draw Circle Center, Radius

Command Circle (or) C Command Sequence

Command : Circle

Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: (pick P1)

Specify radius of circle or [Diameter] <50.0195>: 25 (or pick P2)

(this value is taken as radius of the circle) Circle – Center, Diameter Command : Circle

Specify center point for circle or [3P/2P/Ttr (tan tan radius)]:

(pick P1)

43

Specify radius of circle or [Diameter] <50.0195>: type D

Diameter <50.0195> : 40 ( value of diameter) Circle – 2P ( Two Points) 2P which uses two points on the circumference to form a diameter

Command : Circle

Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: 2P

Specify first end point of the circle’s diameter : pick P1 or specify value of

point

Specify second end point of the circle’s diameter : pick P2 or specify value of

point Circle – 3P (Three Points) 3P which uses any three points on the circumference to form a diameter to

draw the circle. The command can be used in the same way as described

above.

Circle – Ttr ( Tangent, Tangent, Radius)

To use this option you need to have two lines already drawn which can be

described as tangents to the circle to be drawn. Once the tangents are

specified, it will prompt you to enter the radius of the circle. A circle will be

drawn with this radius and the two lines as tangents.

44

Command : Circle

Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: T

Specify point on object for first tangent of the circle : select L1 (line 1)

Specify point on object for second tangent of the circle : select L2 (line2)

Specify radius of the circle < 23.657> : 10 ( specify value of radius)

Circle – Tangent, Tangent, Tangent

To use this option you need to have three lines already drawn which can be

described as tangents to the circle to be drawn. Once the tangents are

specified, a circle will be drawn with these three lines as tangents. The Arc Command

The Arc command allows you to draw an arc of a circle. There are numerous

ways to define an arc, the default method uses three pick points, a start point,

a second point and an end point. Using this method, the drawn arc will start at

the first pick point, pass through the second point and

end at the third point.

Toolbar

Pull-down menu Draw Arc 3 Points Command Arc or A

45

Command Sequence

Command: ARC

Specify start point of arc or [Center]: (pick P1)

Specify second point of arc or [Center/End]: (pick P2)

Specify end point of arc: (pick P3)

You can either pick points or specify the actual value of the

point in terms of X, Y coordinates. The command allows you

to draw an arc by 10 dif ferent methods. All the options work

in the same way as described above. The Continue option

allows you to draw arcs continuously with the last option used.

It will automatically select the end point of the previous arc as

the start point and will prompt you to enter only the end point.

Tips:

1. In AutoCAD Default values are given in like <Default> or <34.878> and

Options are given in square brackets like [ 2P/3P/ Ttr]. Each option is

separated by a forward slash /.

2. To accept the default value/settings press Enter.

3. To use an Option which is not the default just type in the name of the

option. You need not type the entire name, just type the characters

which are given in capital letters. For Example to use option CLose,

there is no need to type the complete name, typing CL is sufficient.

49

Modifying Objects Object Selection

Before you start using the AutoCAD Modify commands, you need to know

something about selecting objects. All of the Modify commands require that

you make one or more object selections. AutoCAD has a whole range of tools

which are designed to help you select just the objects you need. As with so

many aspects of AutoCAD, developing a good working knowledge of these

options can drastically improve your drawing speed and efficiency.

Selecting Objects by Picking

Perhaps the most obvious way to select an object in AutoCAD is simply to

pick it. Those of you who have used other graphics based utilities will be

familiar with this concept. Generally all you have to do is place your cursor

over an object, click the mouse button and the object will be selected. In this

respect AutoCAD is no different from any other graphics utility.

When you start a Modify command such as ERASE, two things happen. First,

the cursor changes from the usual crosshairs to the pickbox and

second, you will see the "Select objects" prompt on the command line. Both of

these cues are to let you know that AutoCAD is expecting you to select one or

more objects.

Select objects:

To select an object, place the pickbox over a part of the object and left-click

the mouse. When the object has been picked it is highlighted in a dashed line

Object selection by Pick Box The selected object highlighted

50

to show that it is part of the current selection and the command line reports "1

found". You will now see the "Select objects" prompt on the command line

again. At this point you can continue adding more objects to the current

selection by picking them or you can press or the Space Bar to complete

the selection.

Window Selection

Selecting objects by picking objects can become quite tedious if you want to

select a large number of objects. Just imagine having to pick a hundred or

more objects in a large drawing! Fortunately AutoCAD provides a number of

selection options which can help you select objects more efficiently. The

Window option is invoked by typing W in response to the "Select objects"

prompt. Window allows you to define a rectangle using two points in exactly

the same way as the RECTANGLE command. Once the window is defined, all

objects which lie entirely within the window will be selected.

Select objects : W

Specify first corner : pick P1 (or any point away from the drawing to be

selected)

Specify opposite corner : pick P2

Object Selection by Window only objects within the window selected

51

Crossing Window Selection

The Crossing Window option is invoked by typing C at the "Select objects"

prompt and is a variation of the Window command. The command sequence

is exactly the same but objects are selected which lie entirely within the

window and those which cross the window border.

Select objects : C

Specify first corner : pick P1 (or any point away from the drawing to be

selected)

Specify opposite corner : pick P2

Objects selected by Crossing Window Objects within and crossing the

window will be selected

The Undo Option

It often happens that you inadvertently add objects which you don't want to a

selection set during its compilation. When this occurs in the middle of a

complicated selection it can be pretty annoying. Fortunately AutoCAD allows

you to undo the last selection made during the compilation of a selection set.

All you need do is enter U at the next "Select objects" prompt to remove the

objects previously added.

52

Selecting All objects

The All option is invoked by typing ALL at the "Select objects" prompt. You

can use this option to select all the objects in the current drawing, no picking

is required.

Select objects : ALL

Using a Previous selection

AutoCAD always remembers the last selection set you defined. This is very

useful because you may need to make a number of changes using different

commands to the same group of objects. In order to re-select the last

selection set you can use the Previous option. The previous option is invoked

by typing P at the "Select objects" prompt

Select objects : P

Tips :

1. Lines, polygons and windows drawn using the selection options do not

exist as drawing objects. Once the selection has been made they

disappear.

2. When you are picking objects in a complex drawing, use the ZOOM

command transparently to make object selection easier. You can Zoom

In or Zoom Out using the wheel on a Scrolling Mouse. Zoom options

can also be selected from the toolbars and are automatically

transparent (it will work within your existing command without canceling

it.)

53

Modify Commands

AutoCAD drawings are rarely completed simply by drawing lines, circles etc.

Most likely you will need to Modify these basic drawing objects in some way in

order to create the image you need. AutoCAD provides a whole range of

modify tools such as Move, Copy, Rotate and Mirror.

As is usual with AutoCAD, the Modify tools can also be accessed in one of

three ways

1. Command names or shortcuts can be entered from the Keyboard

Command : Move (or) M

2. From the Modify Pull-down menu

3. From the Modify Toolbar.

The method you choose is entirely up to you. Ultimately

you will use the method that you feel most comfortable

with or the one you find most efficient. AutoCAD allows

great flexibility and there aren't any right or wrong ways of

working. That said, it should be pointed out that the use

of toolbars in AutoCAD is almost always quicker than any

other method.

54

The Erase Command

The Erase command is one of the simplest AutoCAD commands and is one of

the most used. The command erases (deletes) any selected object(s) from

the drawing. Remember you can always get deleted objects back by typing U

to undo, or using from the Standard toolbar.

Toolbar

Pull-down menu Modify Erase

Command Erase (or) E

Command Sequence

Command : Erase

Select object : pick an object to erase (using any method described above)

Select object : (to end selection and erase the object)

The Copy Command

The Copy command can be used to create one or more duplicates of any

drawing object or objects which you have previously created. Copy is a very

useful and time-saving command because you can create very complex

drawing elements and then simply copy them as many times as you like.

The multiple option allows you to create additional copies of the selected

object(s) by picking as many new points as you like. To invoke the multiple

option type M, at the prompt and it will ask you to specify base point and

second point, select the points as explained below. To end a multiple copy,

just hit the key.

Toolbar

Pull-down menu Modify Copy

Command Copy (or) CP

55

Command Sequence

Command : Copy

Select object : W ( or pick an object to copy using any method described

above)

Specify first corner : pick P1

Specify other corner : pick P2

Select object : (to end selection or you can use any option to select more

objects)

Specify base point or displacement, or [Multiple]: pick P3 Specify second point of displacement or <use first point as displacement>:pick P4

Note: The "Base point", P3 and the "Second point", P4 do not have to be

picked on or near the object. The two points are simply used to indicate the

distance and direction of the copied object from the original object

The Mirror Command

The Mirror command allows you to mirror (get reflection of) selected objects in

your drawing by picking them and then defining the position of an imaginary

mirror line using two points. This command is particularly very useful for

drawing symmetric objects.

Toolbar

Pull-down menu Modify Mirror

Command Mirror

56

Command Sequence

Command : Mirror

Select object : W (or pick an object)

Specify first corner : pick P1

Specify other corner : pick P2

Select object : (to end selection)

Specify first point of mirror line: pick P3

Specify second point of mirror line: pick P4

Delete source objects? [Yes/No]<No> :

Object to be mirrored selected, the selection Mirror image (reflection) of the window and the imaginary mirror line is object shown dashed

The Offset Command

Offset is probably one of the most useful commands for constructing

drawings. The Offset command creates a new object parallel to or concentric

with a selected object. The new object is drawn at a user defined distance

(the offset) from the original and in a direction chosen by the user with a pick

point. You can offset lines, arcs, circles, ellipses, 2D polylines, xlines, rays

and planar splines.

Toolbar

Pull-down menu Modify Offset

Command Offset

57

Command Sequence

Command : Offset

Specify offset distance or [ Through] <1.0000>: specify offset distance

Select object to offset or <exit>: select an object (you can use only pick box)

Specify point on side to offset : pick P1 or select a point on side to offset

Select object to offset or <exit>: or select another object

In the illustration above, a line has been offset to the right by the "Offset

distance" specified and picking a point ‘P1’ to the right of the original line, to

indicate the side to offset . The result is a new line to the right of the original.

Objects can be offset inside or outside to create a new object which is

concentric with the original. In the illustration, a new object has been created

inside of the original by picking a point inside the original object. The distance

between the two objects is the offset distance. The measures of the new

object is the difference of measures of the original object and the offset

distance. In reality, offset objects inherit their object properties from the

original object.

58

The Move Command

The Move command works in a similar way to Copy command except that no

copy is made, the selected object(s) is simply moved from one location to

another.

Toolbar

Pull-down menu Modify Move

Command Move (or) M

Command Sequence

Command : Move

Select object : W ( or pick an object to move using any method described

above)

Specify first corner : pick point

Specify other corner : pick point


objects)

Specify base point or displacement: pick P2 Specify second point of displacement or <use first point as displacement>:pick P3

Objec t Se lec ted to move dur ing move a f te r moving to new

loca t ion

59

The Rotate Command

The Rotate command allows an object or objects to be rotated about a point

selected by the user. AutoCAD prompts for a second rotation point or an

angle which can be typed at the keyboard.

Toolbar

Pull-down menu Modify Rotate

Command Rotate (or) RO

Command Sequence

Command : Rotate

Select object : W ( or pick an object to rotate using any method described

above)

Specify first corner : pick point P1

Specify other corner : pick point P2


objects)

Specify base point : pick P3 (or any point along which rotation desired)

Enter rotation angle or [Reference] : Enter the value say 30

Objec ted se lec ted fo r ro ta t ion objec ted a f te r ro ta t ion

60

The Scale Command

The Scale command can be used to change the size of an object or group of

objects. You are prompted for a pick point about which the selection set will

be scaled. Scaling can then be completed by picking a second point or by

entering a scale factor. For example a scale factor of 2 will double the size of

the objects in the selection set and a factor of 0.5 will half them.

Toolbar

Pull-down menu Modify Scale

Command Scale

Command Sequence

Command : Scale

Select object : W ( or pick an object to scale using any method described

above)

Specify first corner : pick point P1

Specify other corner : pick point P2


objects)

Specify base point : pick P3

Specify scale factor or [Reference] : 2 (or specify a value)

Object selected, before Scaling Object after scaling by a factor 2

61

The Trim Command

The Trim command can be used to trim (cut) a part of an object. In order to

trim an object you must define the "cutting edge". Cutting edges can be lines,

xlines, rays, polylines, circles, arcs or ellipses. The Trim command, unlike

most other modify commands requires that two separate object selections are

made. The cutting edges are selected first (there can be one or more) and

then the objects to be trimmed are selected.

Toolbar

Pull-down menu Modify Trim

Command Trim (or) TR

Command Sequence

Command : Trim

Select Cutting edges……

Select object : All (or pick an object by using any method described above, but ‘ALL’ is preferred as you can trim any object without bothering about multiple selection)


objects)

Select object to trim or shift-select to extend or [Project/Edge/Undo]: pick point

(point marked ‘ X’ on the object to be trimmed)

Select object to trim or shift-select to extend or [Project/Edge/Undo]: pick point

(point marked ‘X’ on the object to be trimmed)

Select object to trim or shift-select to extend or [Project/Edge/Undo]: (to

end) or (pick point marked ‘X’ on the object to be trimmed)

62

Object before trimming cutting edges selected using ALL option

with objects to trim shown by ‘X’

Object after trimming the edges marked ‘X’

Note : At each trimming step you are given the option to undo the previous

trim. This can be very useful if you inadvertently pick the wrong object.

63

The Extend Command

This command extends a line, polyline or arc to meet another drawing object

(known as the boundary edge). In the illustration on the right, two lines are

extended to meet another line (inclined line) which forms the boundary edge.

This command works in a similar way to the Trim command, described above.

Two selections are made, one for the boundary edge(s) and one for the

object(s) to extend.

Toolbar

Pull-down menu Modify Extend

Command Extend

Command Sequence

Command : Extend

Select boundary edges……

Select object : All (or pick an object by using any method described above, but ‘ALL’ is preferred as you can trim any object without bothering about multiple selection)


objects)

Select object to extend or shift-select to trim or [Project/Edge/Undo]: pick P1

(point marked ‘ X’ on the object to be extended)

Select object to extend or shift-select to trim or [Project/Edge/Undo]: pick P2

(point marked ‘X’ on the object to be extended)

Select object to extend or shift-select to trim or [Project/Edge/Undo]: (to

end) (point marked ‘X’ on the object to be extended)

64

Line L1 and L2 before extending boundary edge selected, shown as dashed

Lines L1 and L2 extended up to

the boundary edge

Lines and other objects can be extended in one

of two directions. In the illustration shown on the

right, the line could be extended either to the

right or to the left. You can tell AutoCAD in which

direction to extend by picking a point to the right

or left of the midpoint respectively.

65

The Break Command

The Break command enables you to break (remove part of) an object by

defining two break points. The Break command can be used with lines,

polylines, circles, arcs ellipses, splines, xlines and rays. When you break an

object, you can either select the object using the first break point and then

pick the second break point, or you can select the object and then pick the

two break points.

Toolbar

Pull-down menu Modify Break

Command Break

Command Sequence

Command : Break

Select object : select the object to break

Specify second break point or [First point]: F

Specify first break point : pick P1

Specify second break point : pick P2

66

The Chamfer Command

The Chamfer command enables you to create a chamfer between any two

non-parallel lines as in the illustration below or any two adjacent polyline

segments. Usually, the Chamfer command is used first to set the chamfer

distances before drawing the chamfer.

Toolbar

Pull-down menu Modify Chamfer

Command Chamfer

Command Sequence

Command : Chamfer

(TRIM mode) Current chamfer Dist1 = 10.0000, Dist2 = 10.0000

Select first line or [Polyline/Distance/Angle/Trim/Method]: D (to set distances)

Specify first chamfer distance <10.0000>: 20 (or enter required distance)

Specify second chamfer distance <20.0000>: to accept first distance value

or enter a different value

Select first line or [Polyline/Distance/Angle/Trim/Method]: (pick P1)

Select second line: (pick P2)

The Chamfer command has a number of options. The Polyline option can be

used to chamfer all vertexes of a polyline simultaneously. The Distance option

67

allows you to specify the two chamfer distances. Angle allows the angle

between the first line and the chamfer to be specified. Trim is used to control

whether the original lines are trimmed to the chamfer or remain as they are.

Finally, Method is used to toggle the command between Distance and Angle

mode.

The Fillet Command

The Fillet command is a very useful tool which allows you to draw an arc

between two intersecting lines or adjacent polyline segments. You first need

to use the command to set the required radius and then a second time to

select the lines to fillet.

Toolbar

Pull-down menu Modify Fillet

Command Fillet

Command Sequence

Command : Fillet

Current settings: Mode = TRIM, Radius = 10.0000

Select first object or [Polyline/Radius/Trim]: R (to set

the radius)

Specify fillet radius <10.000>: 25

Select first object or [Polyline/Radius/Trim]: pick P1

Select second object : pick P2

The Fillet command can also be used to fillet arcs and circles. The "Polyline"

option also allows you to fillet all vertices of a polyline with a single command.

Trim is used to control whether the original lines are trimmed to the fillet or

remain as they are.

71

Adding Dimensions and Text

Dimensions

AutoCAD provides a whole range of dimensioning tools which can be used to

quickly dimension any drawing without the need for measurement.

Dimensioning in AutoCAD is automatic; lines, arrows and text are all taken

care of by the dimension commands. AutoCAD dimensions are special blocks

which can easily be edited or erased as necessary.

AutoCAD divides dimensions into four main categories:

Linear

Radial

Ordinate

Angular

When working with dimensions it is very important that line

origins are picked accurately so that the resulting

measurement and text are correct. Always use an Osnap to

pick dimension line origins.

72

Linear Dimensions

The Linear dimension commands are used to dimension along straight lines.

There are five linear dimension commands, namely: DIMLINEAR,

DIMCONTINUE, DIMBASELINE, DIMALIGNED and DIMROTATED. The Linear Dimension Command

Toolbar

Pull-down menu Dimensions Linear

Command DIMLINEAR

Command Sequence

Command : Dimlinear

Specify first extension line origin or <select object> : pick P1

Specify second extension line origin : pick P2 Specify dimension line location or [Mtext/Text/Angle/Horizontal/Vertical/Rotated]: (pick a point to position the dimension line)

The Aligned Dimension Command

You can use this command to generate aligned dimensions. These are

dimensions along inclined lines which cannot be dimensioned with the

DIMLINEAR dimension command because that command will only give a

measured dimension in either a horizontal or vertical direction. However, as

you can see from the command sequence below, this command works in

exactly the same way.

Toolbar

Pull-down menu Dimensions Aligned

Command DIMALIGNED

73

Command Sequence

Command : Dimaligned

Specify first extension line origin or <select object> : pick P1

Specify second extension line origin : pick P2

Specify dimension line location or [Mtext/Text/Angle]: (pick a point to position the

dimension line)

The Radius Dimension Command

Toolbar

Pull-down menu Dimensions Radius

Command DIMRADIUS

Command Sequence

Command : Dimradius

Select arc or circle : pick P1


dimension line)

The Diameter Dimension Command

Toolbar

Pull-down menu Dimensions Diameter

Command DIMDIAMETER

Command Sequence

Command : Dimdiameter

Select arc or circle : pick P1


dimension line)

74

The Angular Dimension Command

Toolbar

Pull-down menu Dimensions Angular

Command DIMANGULAR

Command Sequence

Command : Dimangular

Select arc, circle, line or <specify vertex> : pick P1

Select second line : pick P2


dimension line)

The Baseline Dimension Command

You can use this command to generate a series of dimensions from a single

base point. You must have already created the first dimension in the

sequence using a command such as DIMLINEAR.

Toolbar

Pull-down menu Dimensions Baseline

Command DIMBASELINE

Command Sequence

Command : Dimbaseline

Specify second extension line origin or[Undo/Select] <select> : pick P3


Specify second extension line origin or[Undo/Select] <select> : (or pick

point)

75

In the example above, the "35" dimension was created using the DIMLINEAR

command. The others were created using DIMBASELINE and picking points

P3 and P4.

The Continue Dimension Command

You can use the Continue command to add a string of dimensions. You must

already have created the first dimension in the sequence using a command

such as DIMLINEAR. There is no prompt for the first line origin, AutoCAD

automatically selects the second line origin of the previous dimension to be

the first of the new dimension. There is also no prompt for the dimension line

position, AutoCAD automatically matches up with the previous dimension.

Toolbar

Pull-down menu Dimensions Continue

Command DIMCONTINUE

Command Sequence

Command : Dimcontinue



Specify second extension line origin or[Undo/Select] <select> : (or pick

point)

Using the Continue command you can very quickly generate a string of

dimensions which align perfectly. In the example above, the "35" dimension

was drawn with the DIMLINEAR command; all the other dimensions were

drawn using the DIMCONTINUE command and simply picking the points P3

and P4, one after the other. You can only continue a dimension in a single

direction.

76

The Leader Command

The Leader command can be used to annotate any point on a drawing.

Toolbar

Pull-down menu Dimensions Leader

Command LEADER

Command Sequence

Command : Leader

Specify first leader point or [Settings] <settings> : pick P1

Specify next point :

Specify next point :

Enter text width <0> : (or specify value of width)

Enter first line of annotation text <Mtext> : enter the text

Enter next line of annotation text : (or enter the text)

The Center Mark Command

You can use the Center Mark command to annotate a circle or an arc with a

cross at the center

Toolbar

Pull-down menu Dimensions Center Mark

Command DIMCENTER

Command Sequence

Command : Dimcenter

Select arc or circle : pick on the circumference of circle or arc

A cross is drawn at the center point.

77

Adding Text

Text conveys important information in your drawing. You use text

for t i t le blocks, to label parts of the drawing, to give

specifications, or to make annotations. AutoCAD provides two

ways to create text.

Line Text – used for short simple entries

Mtext (Mult i l ine text) – used for longer entries with

formatting

Using Line Text

Pull-down menu Draw Text Single Line Text

Command : Text

Current text style: "Standard" Text height: 2.5000

Specify start point of text or [Justi fy/Style]: pick a point

Specify height <2.5000>: (or specify value of text height)

Specify rotation angle of text <0> : (or specify angle)

Enter Text : Welcome To AutoCAD (enter the text required)

Enter Text : (or enter the second line of text)

Using Multiline Text (Mtext) For Long complex entries, multiline text can be used. It consists of any

number of text lines or paragraphs that fit within the width specified (by

defining a window). Unlike single-line text, multilline text includes as part of

the same mtext object all text lines or paragraphs created in a multiline text

editing session. You can move, rotate, erase, copy, mirror or scale mtext

objects. Multiline text has more editing options. Using multilane text editor you

can underline, change font, colour, text etc.

78

Toolbar

Pull-down menu Draw Text Multiline Text…

Command MTEXT

Command Sequence Command : Mtext

Specify f irst corner : pick a point ( defines one end of text

window)

Specify opposite corner : pick a point (define opposite end of the

text window)

The text wi l l f i t in this window. Once the window is defined

Mult i l i lne text editor dialog box is displaced as shown below

Using the Character tab of mult i l ine text window you can

enter the text, change the font, change the size of the font,

specify colour, insert symbols

79

Using Properties tab you can change the style, specify

justi f ication of the text, change the width and specify the

rotation angle of the text.

Using the Line spacing Tab you can specify the spacing

between the text

After you enter the text and make the necessary edit ing

choose OK to exit the command. The text wil l then be entered

in your drawing area.

83

Lesson 1 Objective :

At the end of this lesson you will be able to understand the use of

Grid

Snap

Ortho

Line

Erase

Q. Draw the Front Elevation, Plan and the Left Hand End Elevation of the object shown in figure 1.

Figure 1

84

Front Elevation Before you begin to draw, turn the Grid, Snap and Ortho ON.

Step # Command Sequence Description

1. Select command from the

Toolbar or Draw Line

The Line command is invoked

2. From Point : P1 or any point on the screen

3. To point : 80 Move the cursor towards right

4. To point : 10 Move the cursor upwards

5. To point : 80 Move the cursor towards left

6. To point : 10 Move the cursor downwards

7. To point : To end the command




9. From Point : P2 point on the left hand top corner








15. From Point : P3 point on the right hand top

corner





85

Plan Step # Command Sequence Description




2. From Point : P4 Point 20mm (2 dots) above the

left hand top corner of front elev.









9. From Point : P5 Point 20mm (2 dots) to the right

of top left hand corner







14. From Point : P6 Point 20mm (2 dots) to the left of

top right hand corner







19. From Point : P7 Pick point



86

Left Hand Elevation Step # Command Sequence Description




2. From Point : P8 Point 20mm (2 dots) to the left

of the front elev.











11. From Point : P9 Pick the point and turn OFF

Ortho

12. To point : P10 Pick point


14.

Select command from the


This Line is a not visible. It has

to be changed to Hidden

(dashed). How to change to a

hidden line will be discussed in

next lesson.

11. From Point : P11 Pick the point and turn ON Ortho



87

Figure showing the Three Views

88



Grid

Snap

Ortho

Line

Linetype

Dimension

Text

Q. Draw the Front Elevation, Plan and the End Elevations of the object shown in figure 2. Show all hidden surfaces. Also add dimensions and text.

89

Front Elevation Before you begin to draw, turn the Grid, Snap and Ortho ON.












9. To Point : 40 Move the cursor towards left





12. From Point : P3 point on the right hand top

corner





17. To point : pick point P4 To get the inclined line (turn Off

ortho before drawing this line)

18 To point : 20

Move the cursor downwards

(don’t forget to turn On ortho

before you begin to draw the

line)

19 To point : To end the command

90

Plan Step # Command Sequence Description




2. From Point : P5

Point 40mm (4 dots) above the

right hand top corner of front

elev.





7. To point : C To close the figure and end the

command





of top left hand corner








top right hand corner







19. From Point : P8 Pick point



91

Right Hand Elevation Step # Command Sequence Description





of the front elev.






8. To point : C To close and exit command




10. From Point : P10

Point 40mm (4 dots) from the

bottom right hand corner of the

view drawn







Point 20mm (2 dots) to the right

of bottom left hand corner of

view drawn



92

Left Hand Elevation Step # Command Sequence Description





the front elev.






8. To point : C Closes the figure and exits

command





Point 40 mm ( 4dots) from the

bottom left hand corner of the

view drawn



13.




Note : This line has to be

changed to a hidden detail line


Point 20mm (2 dots) to the left of

bottom left hand corner of view

drawn



93

To Change the Line to Hidden Detail Line (dashed)

From the object properties tool bar, select line-type control, then

choose other…. Or Format Linetype….

Line Type Manager dialog box will be displayed

Choose Load

Load or Reload

Linetypes dialog box

will be displayed.

Scroll Down and

select ‘Hidden 2’

Choose OK to close

each dialog box

Select the line(s) you want to change by clicking on them

94

Select linetype control on the object properties toolbar

Choose Hidden 2, the line will be changed to a dashed line

To remove the selection press ‘Esc’ key on the keyboard twice.

Adding Dimensions

Turn On Osnap to select the points precisely before you begin to add

dimensions.


1. From the pull-down menu select Dimension Linear

2. Specify first extension line origin or <select

object> :

Select the end

point of the line

3. Specify second extension line origin : Select the other

end point

4. Specify dimension line location or

[Mtext/Text/Angle/Horizontal/Vertical/Rotated]:

Specify the point

Adding Text


1. Select from the tool bar or Draw Text Multiline text

Mtext Command is

invoked

2. Specify first corner : Pick a point to start

3.

Specify other corner : Specify the other

point, Mtext editor

is displayed

4. Type : FRONT ELEVATION

Change font, size

and justification if

required, Press OK Add the other Dimensions and Text in the same way.

95

Figure showing the four views with dimensions and text

96



Offset

Trim

Extend

Mirror

Q. Draw the Front Elevation, Plan and one of End Elevations of the object shown in figure 3. Obtain the other End Elevation by using Mirror command. Show all hidden surfaces. Also add dimensions and text.

Figure 3

97

To draw 3 boxes one each for front elevation, plan and

LH Elev.

Box for the Front Elevation.


1. Select from the tool bar or

Draw Line

Using Line command to draw

two reference lines

2. From point : Pick point

3. To point : Pick point

Move the cursor downwards and

pick the point to get a vertical

line, without any measure

4. To point : Pick point

Move the cursor towards right

and pick appoint to get a

Horizontal line

5. To point : To end command

6. Select from the toolbar or

Modify Offset

7. Specify offset distance or through

<1.000> : 70

To draw a line at a distance of

70mm from existing line

8. Select object to offset: Select the vertical line

9. Side to offset Select a point on the right side of

the line

10. Select object to offset : To end the command


Modify Offset


<1.000> : 40


40mm from existing line

13. Select object to offset: Select the horizontal line

14. Side to offset Select a point above the line


98

To Trim the Extra Lines

16. Select from the toolbar or Modify

Trim

12.

Select Cutting edges…

Select objects : All

You can use any object

selection method, but

this is preferred

13. Select objects : To end selecting cutting

edges

14. Select object to trim or shift-select to

extend or [Project/Edge/Undo]: pick point

Select a point on the

horizontal line to be

trimmed




horizontal line to be

trimmed




Vertical line to be

trimmed




vertical line to be

trimmed


extend or [Project/Edge/Undo]:

To end the command

99

Box for the Plan


Modify Offset


<1.000> : 20


20mm above the front elev.

3. Select object to offset: Select the top horizontal line in

the front elev.




Modify Offset


<1.000> : 30


30mm above the previous line.




As there are no vertical lines to offset in the plan, we will use Extend

command to extend the vertical lines from the front elev. And then

trim the extra lines (or) you can use Line command to draw them



Modify Extend

Using Extend command to

extend vertical lines from elev.

12. Select boundary edges…..

Select object : select line L1

Select the top horizontal line

13. Select object : End selecting boundary edges

14.

Select object to Extend or shift-

select to trim or

[Project/Edge/Undo]:select L2

Select the vertical line in the

front elev.

15.

Select object to trim or shift-

select to extend or

[Project/Edge/Undo]: select L3

Select the other vertical line in

the front elev.

100

16.


select to extend or

[Project/Edge/Undo]:

To end the command


Modify Trim

To trim the lines between front

elev. and plan

18. Select Cutting edges…


You can use any object selection

method, but this is preferred

19. Select objects : To end selecting cutting edges

20.


select to extend or

[Project/Edge/Undo]: pick point X

Select a point on the vertical line

to be trimmed

21.


select to extend or

[Project/Edge/Undo]: pick X

Select a point on the vertical line

to be trimmed

22.


select to extend or


To end the command

Figure showing the various steps to draw the box for the Plan

101

Box for the Left Hand Elevation


Modify Offset


<1.000> : 20


20mm to the left of front elev.

3. Select object to offset: Select the vertical line on the left

in the front elev.

4. Side to offset Select a point to the left of line



Modify Offset


<1.000> : 30


30mm above the previous line.




As there are no horizontal lines to offset in the LH Elev., we will use

Extend command to extend the horizontal lines from the front elev.

and then Trim extra lines.



Modify Extend

Using Extend command to

extend vertical lines from elev.

12. Select boundary edges…..

Select object : select line L4

Select the vertical line

13. Select object : End selecting boundary edges

14.

Select object to Extend or shift-

select to trim or

[Project/Edge/Undo]:select L5

Select the top horizontal line in

the front elev.

15.


select to extend or

[Project/Edge/Undo]: select L6

Select the other horizontal line in

the front elev.

102

16.


select to extend or


To end the command


Modify Trim


elev. and LH elev.






20.


select to extend or


Select a point on the horizontal

line to be trimmed

21.


select to extend or



line to be trimmed

22.


select to extend or


To end the command

103

To complete the views Front Elevation


Modify Offset

To offset all vertical lines from

the vertical line on the right


<1.000> : 15


15mm

3. Select object to offset: Select the vertical line on the left

in the front elev. box

4. Side to offset Select a point on the right



Modify Offset


<1.000> : 15


15mm from the previous line.

8. Select object to offset: Select the vertical line

9. Side to offset Select a point on the right



Modify Offset


<1.000> : 10


10mm

13. Select object to offset: Select the previous line

14. Side to offset Select a point to the right of line

15. Select object to offset: Select the previous line

16. Side to offset Select a point on the right of line



Modify Offset

To offset Horizontal lines


<1.000> : 8


8mm

20. Select object to offset: Select the horizontal line at

bottom of the box of front elev.

104


22. Select object to offset: Select the horizontal line at top

of the box of front elev.

23. Side to offset Select a point below the line



Modify Offset

To offset Horizontal lines


<1.000> : 10






Modify Offset


<1.000> : 15


15mm




34. Select object to offset : To end the command Trimming the unwanted lines to obtain the actual shape


Modify Trim


elev. and LH elev.






38.


select to extend or


Select a point on the line to be

trimmed

105

39.


select to extend or



line to be trimmed. Continue till

all lines are trimmed

40.


select to extend or


After trimming all extra line and

to end the command

Note : Some lines may not get trimmed as they don’t intersect. Erase them.

In the same way you can complete the Plan and Left Hand

Elevation.

Mirror Image of the Left Hand Elevation to obtain the

Right Hand Elevation


Modify Mirror

To obtain RH Elev. taking mirror

image of LH elev.

2. Select objects : W

3. Specify first corner : Pick a point a little away from LH

elev.

106

4. Specify other corner : Pick a point on opposite corner

5. Select objects : To end selection

6. Specify first point of mirror line :

pick P1

Select the midpoint of the Front

elev.

7. Specify the second point of

mirror line : pick P2

Select a point moving the cursor

vertically

8. Delete source objects [Yes/No]

<No> :

To keep the original object

Figure showing left hand elevation selected for Mirror and Right

Hand Elev. obtained as mirror image. Make necessary changes in the

RH Elev. and Add Dimensions and Text to complete the drawing.

107


At the end of this lesson you will be able to understand the use of Sectional

Views

Hatch

Linetype

Dimension

Text

Q. Draw the Sectional Front Elevation, Plan and one of the End Elevations of

the object shown in figure 4. Obtain the other end elevation by Mirror

Command. Show all hidden surfaces and also add dimensions and text.

Note : 2 holes φ 6 CSK to φ 12 x 4 deep

Figure 4

108

Sectional View : Sectional views are drawn to show the inner details of the

object more clearly. In sectional views it is assumed that the object is cut by a

CUTTING PLANE and one half of the object is removed to see the inside

details. The view drawn after cutting the body is called a sectional view. As

the object is cut, therefore it is necessary to show the solid area in the

sectional view. To show solid area we use hatching lines, which are drawn at

an angle of 45 degrees.

The cutting plane seen as a

rectangle shows how the object

will be cut.

Object cut by a

cutting plane. The

inner details are

seen clearly. The

view drawn will be

called Sectional

Front Elevation as

the object is cut

Parallel to the

front.

109

To Draw the four views of the Object.

The method to draw the views remains the same as discussed in previous

exercises. However the Front Elevation has to be drawn assuming that the

object is cut and the solid area should be represented by hatching lines.

Wherever there is a hole it has to be shown by center line.

Drawing of the views, adding dimension and text is left to you and we will be

discussing how to draw hatching lines and change the line to center line.

To Draw the Hatching Lines



Draw Hatch…

The Boundary Hatch Dialog Box

will be displayed

2. Under Pattern Select ANSI31

The lines are already at 45

degrees. Therefore do not

change angle to 45, let it be zero

3. Click on Pick Points Area where hatching has to be

done

4. Select Internal Point : Select the area wherever it is

marked X

5. Press Enter It will return back to the dialog

box

6. Choose Preview To make sure that it is correct

7. Choose OK To hatch and end the command

To Change the Center Lines

1. Go to Object Properties Toolbar

2. Select Others, Linetype manager will be displayed

3. Select LOAD

4. Select ‘CENTRE 2’ and choose OK to close each window

5. Select the line to change, and select CENTRE 2 from the toolbar

110

Figure Showing the Front Section

111

Exercise Problems

Ex. 1-1 Ex. 1-2

Ex. 1-3

Ex. 1-4

112

2 holes φ 8 CSK to φ 12 x 4 deep

Ex. 1-5 Ex. 1-6

φ 8 C’Bore to φ 12 x 12 deep

Ex. 1-7 Ex. 1-8

113

Ex. 1-9

Ex. 1-10 Ex. 1-11

117

Working with 3D

Introduction

You may have already found out why CAD has many advantages over

manual drafting. One big advantage is that once you've drawn something, you

shouldn't have to draw it again. If you manually drew a house plan or any

object, you would have to draw a front elevation, side elevations, and possibly

a perspective view. With one 3-D CAD model, you can generate views from

any angle.

There are THREE types of 3D Modeling available in AutoCAD

Wire-frame Modeling

1. A wire-frame model is assumed to be made by connecting

wires to obtain the required shape.

2. A wire-frame model will not have AREA or VOLUME

3. As it has no area and no volume, we cannot perform any

mass property calculations.

Surface Modeling

1. A surface model is made of surfaces(planes).

2. A surface model has AREA but NO VOLUME

3. Mass properties cannot be calculated as it has no volume.

Solid Modeling

1. A 3-D model created using solid 'building blocks'. This

is the most accurate way of representing real-world

objects in CAD.

2. It has both AREA and VOLUME

3. All Mass/Material Properties can be calculated.

118

Isometric Drawing

This is the simplest way to give a 3-D representation while using only 2-D

commands. This has been the usual way of doing things before CAD allowed

true 3-D work to be done. Many times an isometric drawing is used to

compliment a 3 view orthographic drawing.

Setting up Isometric Grid and Snap

Right Click on GRID or SNAP in the status bar or

Tools Drafting Settings…

The Drafting Settings dialog box will be displayed, click on the Snap

and Grid Tab

Under Snap type & style select Isometric Snap

The Grid will be displayed which will be at an angle of 30 degrees

AutoCAD has a command called ISOPLANE which allows you to easily draw

at a 30 degree angle as needed for an isometric drawing. To understand the

119

isoplanes consider a 3D box. In the isometric view of the box you will be able

to see three surfaces. In AutoCAD we call them as Isoplane Left, Isoplane

Right and Isoplane Top. But when you are actually drawing one of the

isoplanes (left or right) is assumed as the front view. To make a 3D drawing

you need to switch between these planes in order to draw on the particular

surface. You can switch between the three 'isoplanes', by using ISOPLANE

command or by pressing the F5 key.

Figure Showing the Grid rotated at 30 degrees and the Isoplanes

120



Isometric Grid and Snap

Isoplanes

Use of 2D commands to create 3D drawings

Q. Draw the Isometric View of the object shown in figure

Figure 5

121

To Draw the Isometric View

Right Click on GRID or SNAP in the status bar or Tools Drafting Settings… Switch on the Grid and Snap

Under Snap type & style select Isometric Snap








5. Press F5 To toggle to Isoplane Top


7. Press F5 To toggle to Isoplane Right



10. Press F5 To toggle to Isoplane left









17. From Point : P2 Pick the point

18. Press F5 To toggle to Isoplane top


20. Press F5 To toggle to isoplane right



122

23. Press F5 To toggle to isoplane left


25. To point : To end command




27. From point : P3 Pick point P3






31. From point : P4 Pick point P4



Figure showing the various steps of drawing the Isometric view

123

To make the two holes

A hole is round, but in isometric it doesn’t look like a perfect circle. We will use

the Ellipse command.


Toolbar or Draw Ellipse

The Ellipse command is invoked

35. Specify axis endpoint of ellipse or

[Arc/Centre/Isocircle] : I

Select I for Isocircle

36. Specify center of Isocircle : P5 Pick point

37. Press F5 To toggle to isoplane top

38. Specify radius of Isocircle or

[Diameter] : 10 Specify the radius of circle

39.


Toolbar or Draw Ellipse

To draw the circle at the bottom

which is partially seen and

should be trimmed later

40. Specify axis endpoint of ellipse or

[Arc/Centre/Isocircle] : I

Select I for Isocircle

46. Specify center of Isocircle : P6 Pick a point 10mm below the

center of previous circle

48. Specify radius of Isocircle or

[Diameter] : 10 Specify the radius of circle

To Trim the part of the circle which is not visible


Modify Trim

12.

Select Cutting edges…

Select objects : select the top

circle

It will be the cutting edge


14. Select object to trim or shift- Select the part(s) of the circle

124

select to extend or

[Project/Edge/Undo]: pick point

which is not visible

15.


select to extend or


Once all parts are trimmed to

end command

In the same way as described above draw the other hole on the

vertical surface and trim the extra part of the circle which is hidden

behind the surface

The Isometric View of the Object

125

Exercise Problems

Ex. 2-1

Ex. 2-2

Ex. 2-3 Ex. 2-4

126

Ex. 2-5 Ex. 2-6

Ex. 2-7 Ex. 2-8

Documents

AutoCAD Lab Manual