Aragaw Gebremedhin auto cad lecture notes

MACHINE DRAWING WITH
AUTO CAD
1
BY: ARAGAW G/MEDHIN (MSc)-Ethiopia

What is your
expectation from the
course
???
2

COURSE CONTENT
1. Introduction to Basic CAD software
2. Basic Drawing & Editing Commands
3. Drawing Precision in CAD
4. Text Annotation and Dimensioning:
5. Introduction to 3D Drawings
6. Introduction to parametric design (Pro
Engineer
3

Content:
 Basic principles of auto CAD
 Introduction to AutoCAD
CAD window;
Setting up of a new drawing;
Working with an existing CAD
files;
Hardware and Software tips 4
1. Introduction to Basic CAD software

Introduction to AutoCAD
 The role of computer in mechanical engineering
may be broadly classified in to two groups
1. Monitoring and controlling the mechanical
process. E.g. CNC, PLC, Robotics etc.
2. Support mechanical process applications.
 Which deals essentially with the preparation
for actual manufacturing and post
manufacturing operations.
 All the support functions that computers can
provide for the successful completion of
manufacturing operations.
 The types of support can be CAD, CADD, CAE,
CAM, CAPP, CATD, CAP. 5

Introduction to AutoCAD
What is Auto CAD?
 AutoCAD is a software package used for
Drafting and designing almost anything
you wish.
 Design software developed by Auto-Desk.
 First released in 1982 under the name
‘MicroCAD’.
 Revolutionary drafting and design tool.
 Translated into more than 18 different
languages.
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 CAD: Computer Aided Design
 Use of computer methods to develop the geometric
model of the product(2D-3D)
 It involves basically developing, analyzing and
modifying designs using computers.
 CADD: Computer Aided Design and Drafting
 Combine the CAD function with drafting
 Used to generate the production drawing of the
part(detail drawings)
 CAE: Computer Aided Engineering
 The use of computer method to support basic error
checking, analysing, optimization, manufacturability,
etc of a product design. Like ANSIS-used to analyze
mechanical forces.
Terminology related to AutoCAD
7

 CAM: Computer Aided Manufacturing
 Refers to computer software used to develop the CNC-
part programs for machining and other process
applications.
 CAPP: Computer Aided Process Planning
 Use of computer to generate the process plans for
complete manufacture of products and parts.
 CATD: Computer Aided Tool Design
 Used for developing the tools for manufacture such as
jigs and fixtures, dies and moulds.
 CAP: Computer Aided Planning
 Involves the planning functions such as material
requirement planning, computer aided scheduling etc.
Cont’d
8

Application of CAD
 CAD may be applied in the field of
both social and natural sciences as
far as they need to sketch or draw
some thing with the help of
computers.
 Specifically it can be applied in:
 Mechanical engineering
 Civil engineering
 Electrical engineering etc
9

Design Examples
LeMans Race Car
Paintball Mask
Dentist Chair

Design Examples
John Deere Combine
Automatic Bus Transmission

Advantages of CAD
1. Faster rate of producing drawing
2. Greater accuracy of drawing
3. Neat and clear drawing
4. No reputation of design/drawing is just copy and
past with in a second
5. Special drafting techniques like zoom, rotate,
move, copy, mirror etc
6. Quickly and accurately dimensioning of various
components.
7. Superior design forms like finite element analysis
8. Integrating design department with other
department. Like CAM.
12

Now let us see how
to start CAD?
13

I. Starting Auto CAD
 There are three methods of starting auto CAD
1. Opening Auto CAD from All programs
 Start all programs Auto desk
AutoCAD2008 AutoCAD2008
2. Opening Auto CAD from desktop
 Right-click on the shortcut icon on desk top the
drop-down menu appear then click on Open
 On the screen /desktop/ double click on the
AutoCAD2008 shortcut icon.
3. Opening Auto CAD from program file
 My comp C program file autocad2008
acad double click on it or Right-click and open
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II. Graphic window(user interface)

Basic Toolbars
(AutoCAD Environment)
Menu
ToolBars
Command Window
Drawing Area
Status Bar
standard toolbars

Basic components of CAD windows
1. Title bar
2. Menu bar
3. Drawing Area
4. Command pallet (area)
5. Status bar:
6. Toolbars
 Standard toolbar
 Object property toolbar
 Drawing toolbar
 Modifying toolbar
 Style toolbar
 Layer toolbar etc
17

The Auto CAD Interface cont’d
1. Title bar:
 This is found at the top of the window
and it is by default with blue color.
 It shows:
 The auto cad version
 The file location
 The file name with its extension.
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2. Menu bar:
 It is found at the top of the window
immediately below the title bar.
 It contains File, Edit, View, Insert,
Format, Tools, Draw, Dimension, Modify,
Express, Window and Help.
 These menus are sometimes called pull
down menus.
19

3. Drawing Area:
 It is the area that we can draw and edit
our drawings.
 It also contains :
 the UCS (user coordinate system),
cross hair
 There are two types of drawing areas:
 Model window,
 Layout window,
20

4. Command line:
 Is used to insert necessary instruction to the
software.
 It is used to Displays and prompts
messages.
 The default position of the command line is
the bottom of the window immediately
above the status bar.
 To display/hide the command line press
ctrl+9 on the keyboard
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5. Status bar:
 This part of auto cad window is found at the bottom of the
window.
 It contains:
 SNAP
 GRID
 ORTHO
 POLAR
 OSNAP
 MODEL / PAPER
 We can display or hide elements of status bar by
the status bar menu icon.
 Also display x, y and z coordinate of the cursor.
 A click on a button turns that function on, if it is
off, a click on a button when it is off turns the
function back on.
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6. Tool bars:
 It Contains many icons of a particular category
to access a command position without using
menu system.
 There are above 30 toolbars Some of them are
for 2D window tasks and some are for only 3D
window tasks and the others are for both 2D
and 3D window tasks.
 The toolbars that we frequently use are:
 Standard toolbar,
 Draw toolbar,
 Modify toolbar,
 Layers toolbar,
 Properties toolbar,
 Dimension toolbar,
 Styles toolbar,
 Inquiry toolbar,
 Visual styles or Shade,
 View port,
 View,
 Modeling toolbar,
 Orbit,
 Text, and etc
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A. Standard toolbar
 Standard toolbar is docked at the top of the
AutoCAD window under the Menu bar.
 It contains basic commands like open, save, print,
etc
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cont’d

B. Object properties
 You can use the controls in the Properties
toolbar to view, set, and modify the
properties.
 The Properties toolbar provides convenient
access to the most important object
properties, Such as; Color, Line type, Line
weight, and Plot style,
25
cont’d

C. Layers
 Layers are a way of managing, tidying and also controlling
the visual layout of a drawing.
 Layers are used to group information in a drawing by
function and to enforce linetype, color, line weight and other
standards.
 This makes working with very complicated drawings much
more easier and efficient.
 Layers are effective way of ordering your drawings.
26
cont’d

27
 In Auto CAD, we make individual layers For
things like:
 Part drawing
 Dimensions
 Hidden lines
 Center lines
 Section lines
 Break lines
cont’d

Other terms used in ACAD
 Dialog box: is a menu(command box)
which appears after selecting a command
like point style, insert, color etc.
 In dialog box their may be one/both of the
following options
A. Tabs: a way/guide to bring a sub-dialog on screen.
B. Check boxes: guide to on off the indicated functions
C. Radio button: to indicate the feature description.
D. Slider: have pointer can be dragged to change size of
the feature controlled. 28

III. Setting of paper (Drawing area)
1. UNIT STYLE
 Used to select any unit system (metric or inch)
and precision which can be displayed on a
coordinates or dimensions.
 To promote the unit basically there are two
methods
a. METHOD-I: using command window
 Type units and enter in a command
window
b. METHOD-II: using menu bar
 Menu – Format – Units then select the
units and precisions
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Setting of paper………..
2. DRAWING LIMIT
 Is the invisible boundary to fit the drawing
 It should be large enough to contain the
drawing and other related parts of it
 To promote there are two methods
 Type Limits and enter in a command
window
 Menu – Format – drawing limit then specify
the size of paper (use 0,0 and 420,297 as default)
 To activate the selected limit in command window type Z
enter and A enter 30

3. Drafting setting
 Is used to set Snap, Grid, Polar, Object
Snap Dynamic inputs etc
 To promote there are two methods
 Type ds and enter in a command window
 Menu – tools – draft settings then specify
Snap and Grid, Polar, Object Snap
Dynamic inputs etc
Setting of paper………..
31

Saving files
 Saving files: To save a file we have to consider;
 file location
 file name
 file type like
.dwg: AutoCAD drawing
.dws: AutoCAD Drawing Standard
.dwt: AutoCAD Template Drawing template file
.dxf: AutoCAD Data Exchange Format
 Remember: after you set the paper size units and other
necessary thing it is better to save the file as your
template this can save a lot of time 32

Executing toolbars
 It is known as calling toolbars
 If there is no tool bars except menu bar,
command window and title bar on CAD-window
there are two methods of calling tool bars:
1. Using commanding window follows steps:
 Write CUI enter (customize user interface)
 Cui dialog box appears on the first area:
 Select ACAD Right click on it Select
Reset ACAD warning dialog box come
click yes then click apply then ok
 Then go to Tool work space check Autocad
classical then standard tool bars will appear.
33

Cont’d
2. To add or call other necessary tool
bar other than the standard one
use the following steps:
 Right click in any toolbar
 Dropdown menu will come then
 Select the toolbars you want to
see on ACAD graphic window.
34

Now every
preparation is made
so next it is time
to play games with
CAD
35

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2. Basic Drawing &
Editing Commands

2. Basic Drawing & Editing Commands
CONTENTS
 Drawing Lines;
 Drawing circles and circular arcs;
 Drawing ellipse and elliptical arcs;
 Drawing polygons;
 Drawing Curves (Sketch);
 Creating regions;
 Hatching areas
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I. Basic Geometrical objects and Tools
CONTENTS
1. Line
2. Polyline
3. Multi line
4. Polygons
5. Rectangle
6. Arc
7. Circle
8. Ellipse
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1. Drawing of lines
 There are d/t methods of drawing a line
METHOD-I: using Grids and Snap command
 Set grid and snap (10 and 5 as default)
 Turn on grid and snap others off
 Move the cursor until the following coordinates are
shown in the status bar
1. 60,140
2. 80,140
3. 80,120
4. 100,120
5. 100,100
6. 80,100
7. 80,50
8. 85,50
9. 85,40
10. 55,40
11. 55,50
12. 60,50
13. 60,100
14. 40,100
15. 40,120
16. 60,120
17. 60,140
1
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METHOD-II: using Ortho command(direct entry
method)
 Turn ‘on’ ORTHO and off others
 Menu – Draw-Line
 First point: pick on any point or specify
x, y
 Second point: drag to right/left enter
the dimension and enter/right-click
 Practice this:-
Drawing of lines….
40

METHOD-III: using coordinate entry methods
(CEM)
 Basically there are Four CEM
A. Cartesion coordinate system(x,y,z)
 Is used to explain a point by giving the x, y and z axis
coordinates
Eg. Draw an object using the following x,y & z
1. St.(20,10,0)
2. 30,10,0
3. 30,20,0
4. 40,20,0
5. 40,30,0
6. 10,30,0
7.10,20,0
8. 20,20,0
9. 20,10,0(or type
C and enter)
Drawing of lines…..
41

B. Absolute coordinate systems(x , y)
 Is used to draw the object only by feeding
the x & y coordinates from the origin.
Eg. Draw an object using the following x & y
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1. St.(20,10)
2. 30,10
3. 30,20
4. 40,20
5. 40,30
6. 10,30
7.10,20
8. 20,20
9. 20,10(or type C
and enter)

C. Relative coordinate system(@x , y)
 Is a method used to draw a line relative
to the current position of a cursor OR the
point which drawn previously.
Eg. Draw an object using the following x &
y coordinates:- draw- line- then enter
below
1. 10,10
2. @40,0
3. @0,10
4.@-30,0
5.@0,10
6.@30,0
7.@0,10
8.@-30,0
9.@0,10
10.@30,0
11.@0,10
12.@-40,0
13.@0,-50 or
type C and
press enter
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D. Polar coordinate system(D<θ)
 A method used to draw an object if the
distance D and the angle θ b/n the
coordinates are given
Eg. Draw an object using the following
D&θcoordinates:- draw- line- then enter below
1. 50,50
2.@20<0
3.@20<60
4.@20<120
5.@-20<0
6.@20<240
7.@20<300 or type C and press enter
44

Multiline: Are composed of one or more
parallel line called elements
 It is basically used to draw building
and factory layout drawings.
 To promote multiline
 Using menu bar: draw-multiline
2. Drawing of Multi line
45

Polyline: is a continuous line used to construct
continuous polygons like triangles, rectangle
etc.
 It is a series of connected line and arc
segments created as one object.
 Width of the object can also be controlled.
 To promote Polyline
 Using menu bar: draw-Polyline
 Using command window: type pl or pline then
enter- specify points
3. Drawing of Polyline
46

The Polyline cont’d
 The Polyline Command is found at:
 Toolbar : Draw
 Dashboard:
Steps to create Polyline
a. To draw a Polyline with straight segments
1. Take a Polyline command,
2. Specify the first point of the polyline,
3. Specify the endpoint of the first Polyline segment,
4. Continue specifying segment endpoints as needed,
5. Press ENTER to end, or enter c to close the
Polyline.
47

b. To draw a line and arc combination Polyline
2. Specify the start point of the polyline
segment,
3. Specify the endpoint of the Polyline segment,
 Switch to Arc mode by entering a (Arc) on
the command line,
 Return to Line mode by entering L (line),
4. Specify additional polyline segments as needed,
5. Press ENTER to end, or enter C to close the
Polyline.
48

c. To create a wide Polyline
2. Specify the start point of the line segment,
3. Enter w (Width,
4. Enter the starting width of the line segment,
5. Specify the ending width of the line segment using
one of the following methods:
 To create a line segment of equal width, press
ENTER,
 To create a tapering line segment, enter a
different width,
5. Specify the endpoint of the polyline segment,
6. Continue specifying segment endpoints as needed,
7. Press ENTER to end, or enter c to close the polyline,
49

 Polygons: Is a plane figure with at least three
straight sides and angles, and typically five or
more.
 The Polygon command is the simplest method
for creating equilateral triangles, squares,
pentagons, hexagons, and so on.
 Use polygon to create closed polylines with
between 3 and 1,024 equal-length sides.
 The Polygon Command is found at:
 Toolbar: Draw
 Dashboard:
 Pull-down: Draw  Polygon
 Keyboard: POLYGON shortcut POL
4. Drawing of Regular Polygons
50

I. Inscribed in a Circle
Steps:
1. Take a Polygon command,
2. Enter the number of sides, for
example, 6,
3. Specifies the center to location
for the center of the polygon
4. Specify the Inscribed type I and
enter. This determines how the
distance that you enter in the
next prompt is measured
51
Drawing of Polygons……
 There are three ways of constructing a polygon

II. Circumscribed about Circle
Steps:
2. Enter the number of sides,
for example, 6,
3. Specifies the center to
location for the center of the
polygon
4. Specify the Circumscribed.
type C and enter, This
determines how the distance
that you enter in the next
prompt is measured
Regular Polygons………..
52

III. Edge
 Steps to draw a polygon by specifying
one edge:
2. On the command line, enter the
number of sides,
3. Select (Edge): type e and Enter
4. Specify the start point for one
polygon segment.
5. Specify the endpoint of the
polygon segment.
6. Click to define orientation for the
polygon.
Regular Polygons………..
53

5. Drawing of Rectangle
 The Use of Rectangle is to create closed polylines
in a rectangular shape.
 The Rectangle Command is found at:
 Toolbar: Draw
 Dashboard:
 Pull-down: Draw  Rectangle
 Keyboard: RECTANGLE shortcuts REC
 This command is promoted: Specify first
corner point or [Chamfer/ Elevation/ Fillet/
Thickness/ Width]:
The Rectangle command
54

The Rectangle cont’d
Notice that; instead of picking a second point to
draw the rectangle ,you have option of entering
dimensions. You can specify the length, width,
area, and rotation parameters.
Steps:
1. Take a Rectangle command,
2. Specify the first corner of the rectangle,
3. Specify the other corner of the rectangle, or
4. Enter ‘D’ for dimension,
5. Give length value,
6. Give width value,
7. Click for orientation. 55

 The Arc Command is found at:
 Toolbar: Draw
 Dashboard:
 Pull-down menu: Draw  Arc
 Keyboard: Arc shortcut A
 Steps: To draw an arc by specifying three
points
1. Take the arc command,
2. Specify the start point,
3. Specify a point on the arc,
4. Specify the endpoint.
6. Drawing of Arcs
56

 There are 11- methods used to draw an arc
 To call go to menu bar-Draw-Arc-the following
drop-down menu is appear then select the
method you want.
Drawing of Arcs…..
57

 The circle Command is found at:
 Toolbar: Draw
 Dashboard:
 Pull-down menu: Draw  Circle
 Keyboard: Circle shortcut C
 Steps:
1. Take the circle command,
2. Specify the center point,
3. Specify the radius or diameter.
7. Drawing of circle
58

 There are 6-d/t methods
used to draw a circles.
 These are:
1. Center , Radius
2. Center , Diameter
3. 2 point method
4. 3 point method
5. Tan , Tan, Radius and
6. Tan, Tan, Tan
Drawing of circle….
59

 Donuts are filled rings or solid-filled
circles that actually are closed Polyline
with width.
 To create a donut, you specify its inside
and outside diameters and its center.
 You can continue creating multiple
copies with the same diameter by
specifying different center points.
 To create solid-filled circles, specify an
inside diameter of 0.
8. The Donut Command
60

The Donut cont’d
 The Donut Command is found at:
 Pull-down menu: Draw  Donut
 Keyboard: DONUT shortcut DO
 Steps:
1. Take the command,
2. Specify the inside diameter,
3. Specify the outside diameter,
4. Specify the center of the donut,
5. Specify the center point for another
donut, or press ENTER to complete the
command. 61

 There are 3- methods used to draw an arc
 To call go to menu bar-Draw-Ellipse-the
following drop-down menu is appear then
select the method you want.
9. Drawing of Ellipse
62

 You can hatch an enclosed area or hatch within a
specified boundary using HATCH.
 By default, HATCH creates associative hatches that are
updated when the boundary is changed.
 You create a hatch by selecting an object to hatch or by
defining a boundary and then specifying an internal
point.
 A hatch boundary can be any combination of objects,
such as lines, arcs, circles, and Polyline, that forms an
enclosed area.
 The Hatch and Gradient Command is found at:
 Toolbar: Draw
 Dashboard:
 Pull-down menu: Draw  Hatch/gradient
 Keyboard: Hatch shortcut H 63
10. Hatch and Gradient

Hatch and Gradient Cont’d
 To hatch areas
1. Take the Hatch or Gradient command,
2. In the Hatch and Gradient dialog box, click Add:
Pick points
3. In your drawing, specify a point inside each area
that you want hatched, and then press ENTER.
This point is known as the internal point.
4. In the Hatch and Gradient dialog box, Hatch tab,
in the swatch box, verify that the sample pattern
is the pattern you want to use. To change
patterns, select another pattern from the Pattern
list.
5. Click OK. 64

11. Layer
What is a Layer?
 A layer can be thought of as a large piece
of clear plastic, as infinitely large as the
drawing area in Autocad.
 When drawing in Autocad, everything is
drawn on the default layer which is set
current. Only the objects you are drawing
are visible on the layer, the layer itself
can never be seen - it is invisible.

Layers
 In Auto CAD, we make individual
layers…
 For things like
 Hidden lines
 Center lines
 Section lines
 Break lines
 Layers are a way of managing, tidying and
also controlling the visual layout of a
drawing.
 A whole section of a drawing can be turned
on or off, or simply one aspect can be
controlled - text for example.

Layers
 This is all done by using layers within
Autocad.
 Layers are controlled by the layer properties
manager button which is located on the
object properties toolbar:
 Each new layer is created by you, the user.
Normally, it is acceptable to have a layer for
each different part of a drawing.

In Layer Property manger
 Add a New Layer - Press the New button to
create a new layer.
 Delete a Layer - Press the delete button to
delete the selected layer.
 Set Current layer - Press the current button to
set the selected layer current. All objects drawn
will then be drawn on this current layer.
 Show Details - Press the show details button
to see more detailed information about the
selected layer.
 Each layer also has the following options against
it:

Layer property Manger
 Name - Displays the layer name.
 On - Controls if the layer is on or off. Select the light bulb to turn the layer
off on the drawing.
 Freeze in all VP - Pressing this will freeze the layer in all viewports as well
as the current model view (see lesson 10 to learn about viewports)
 Lock - This handy feature locks a layer preventing any content of the layer
from being modified.
 Colour - Change this to whichever colour you like. All objects drawn on the
layer will display the chosen colour provided that the objects colour setting in
the object properties toolbar (shown above) is set to 'By Layer'.
 Linetype - Set the default linetype for all objects drawn on the layer. i.e
continuous, dashed, dotted etc.
 Lineweight - Set the thickness a line appears .Default is no thickness. This
option can be toggled on/off on the display by the LWT button above the
command console.
 Plot - Select if the layer will be shown when the drawing is plotted (printed).
 The current layer, layer colour, linetype and lineweight can all be controlled
outside of the layer properties manager via the object properties toolbar.

Exercise-1 ***
Additional
1. Draw polygon having 3, 5, 6, 7, 8 sides
inscribed and circumscribed about a
circles of diameter 40.
2. Draw a two different rectangle and practice
create Hatch and Gradient.
71

72
3. Drawing
Precision in CAD

3. Drawing Precision in CAD
CONTENTS
Advanced editing commands
Using Object Snap;
Making changes in a drawing;
Changing an object's length;
Blocks and Attributes.
73

Modifying Tools
 Are the tools used to modify the
existing/current drawings to change their
shapes or some parts of it.
 To call go to menu bar-modify-the following
drop-down menu is appear then select the
method you want.
 Some of the basic modifying tools are: Erase,
Copy, Mirror, Offset, Array, Move, Rotate,
Scale, Trim.
 Most of Modify tools can be accessed in one of
the following four ways;
1. By Keyboard,
2. By Dashboard,
3. By Modify Pull-down menu,
4. By Modify Tool bar,
74

1. The Erase Command
 The Erase Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Erase
 Keyboard: ERASE; Shortcut: E
 Steps:
1. Take Erase command,
2. Select Objects to erase,
3. Enter.
75

2. The Copy Command
 The Copy Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Copy
 Keyboard: COPY; Shortcut: Co
 Steps:
1. Take Copy command,
2. Select Objects to copy,
3. Specify the base point,
4. Specify the destination point, or points
5. Enter to end. 76

3. The Mirror Command
 The Mirror Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Mirror
 Keyboard: Mirror; Shortcut: Mi
 Steps:
1. Take Mirror command,
2. Select Objects to mirror,
3. Specify the first and the second point of the
mirroring line
4. Enter Y or N for erasing the original object
or not.
77

4. The Offset Command
 The Offset Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Offset
 Keyboard: OFFSET; Shortcut: O
 Steps:
1. Take Offset command,
2. Select Objects to offset,
3. Specify offset distance or the through point,
4. Specify the direction or the through point,
5. Enter to end.
78

 Array command is used to Creates multiple
copies of objects in a pattern.
 Use the Rectangular Array option to create an array of
rows and columns of copies of the selected object.
 Use the Polar Array option to create an array by
copying the selected objects around a center point.
Menus
 Toolbar: Modify
 Menu: Modify Array...At the Command
prompt, enter array.
 Command entry: array
79
5. The Array Command

I. To create a Rectangular array
1. Click Modify menu Array....At the Command prompt, enter array.
2. In the Array dialog box, select Rectangular Array.
3. Click Select Objects. The Array dialog box closes. You are prompted for
object selection.
4. Select the objects to be arrayed and press ENTER.
5. In the Rows and Columns boxes, enter the number of rows and columns in the
array.
6. Specify the horizontal and vertical spacing (offsets) between objects by using
one of the following methods:
 In the Row Offset and Column Offset boxes, enter the distance between rows and
between columns. Adding a plus sign (+) or a minus sign (-) determines direction.
 Click the Pick Both Offsets button to use the pointing device to specify the
diagonal corners of a cell in the array. The cell determines the vertical and
horizontal spacing of the rows and columns.
 Click the Pick Row Offset or Pick Column Offset button to use the pointing device
to specify the horizontal and vertical spacing. 80

7. The example box displays the result.
8. To change the rotation angle of the array, enter the new
angle next to Angle of Array.
9. The default angle 0 direction setting can also be changed in
UNITS.
10. Click OK to create the array.
81
To create a Rectangular array…..

1. Click Modify menu Array....At the Command prompt, enter array.
2. In the Array dialog box, select Polar Array.
3. Next to Center Point, do one of the following:
 Enter an X value and a Y value for the center point of the polar
array.
 Click the Pick Center Point button. The Array dialog box closes
and you are prompted for object selection. Use the pointing device
to specify the center point of the polar array.
4. Click Select Objects. The Array dialog box closes and you are
prompted for object selection.
5. Select the objects to be arrayed.
6. In the Method box, select one of the following methods:
 Total Number of Items & Angle to Fill
 Total Number of Items & Angle Between Items
 Angle to Fill & Angle Between Items 82
II. To create a Polar array

7. Enter the number of items (including the original object), if available.
8. Use one of the following methods:
 Enter the angle to fill and angle between items, if available. Angle to Fill
specifies the distance to fill around the circumference of the array. Angle
Between Items specifies the distance between each item.
 Click the Pick Angle to Fill button and the Pick Angle Between Items
button. Use the pointing device to specify the angle to fill and the angle
between items.
 The example box displays the result.
9. You can set any of the following options:
7. To rotate the objects as they are arrayed, select Rotate Items As Copied.
The example area displays the result.
8. To specify the X,Y base point, select More, clear the Set to Object's
Default option and enter values in the X and Y boxes, or click the Pick
Base Point button and use the pointing device to specify the point.
10. Click OK to create the array.
83
To create a Polar array …..

6. The Move Command
 The Move Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Move
 Keyboard: Move; Shortcut: M
 Steps:
1. Take Move command,
2. Select Objects to move,
3. Specify a base point for the move.
4. Specify the destination point,
 The objects you selected can be moved to a new
location determined by the distance and direction
between the first and second (destination) points.
85

7. The Rotate Command
 The Rotate Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Rotate
 Keyboard: ROTATE; Shortcut: Ro
 Steps:
1. Take Rotate command,
2. Select Objects to rotate,
3. Specify the base point for the rotation,
4. Do one of the following:
86

The Rotate Cont’d
a. Enter the angle of rotation.
b. Drag the object around its base point
and specify a point location to which
you want to rotate the object.
c. Enter c to create a copy of the selected
objects.
d. Enter r to rotate the selected objects
from a specified reference angle to an
absolute angle
87

8. The Scale Command
 The Scale Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Scale
 Keyboard: SCALE; Shortcut: Sc
 Steps:
1. Take Scale command,
2. Select Objects to scale,
3. Specify the base point,
4. Do one of the following:
a. Enter the scale factor, or
b. Drag and click to specify a new scale, or
c. Enter r (Reference); then
 Select the first and second reference points, or
 enter a value for the reference length. 88

9. The Stretch Command
 The Stretch Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Stretch
 Keyboard: STRETCH; Shortcut: S
 Steps:
1. Take Stretch command,
2. Select Objects with cross window selection,
The crossing window must include at least
one vertex or endpoint.
3. Specify the base point for the stretch, and
then specify a second point, to determine
the distance and direction.
89

10. The Trim Command
 The Trim Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Trim
 Keyboard: TRIM; Shortcut: Tr
 Steps:
1. Take Trim command,
2. Select the objects to serve as cutting
edges, To select all displayed objects as
potential cutting edges, press ENTER without
selecting any objects.
3. Select the Objects to trim.
90

11. The Extend Command
 The Extend Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Extend
 Keyboard: EXTEND; Shortcut: Ex
 Steps:
1. Take Extend command,
2. Select the objects to serve as boundary
edges, To select all displayed objects as
potential boundary edges, press ENTER without
selecting any objects.
3. Select the Objects to extend.
91

12. The Join Command
 The Join Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Join
 Keyboard: JOIN; Shortcut: J
 Steps:
1. Take Join command,
2. Select the source object to which you want to
join objects.
3. Select one or more objects to join to the
source object. (Valid objects include arcs, elliptical
arcs, lines, Polyline, and spines)
4. Enter. 92

13. The Chamfer Command
 The Chamfer Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Chamfer
 Keyboard: CHAMFER; Shortcut: Cha
The Chamfer command enables you to create a
chamfer between any two non-parallel lines.
Usually, the Chamfer command is used to set the
chamfer distances before drawing the chamfer.
93

The Chamfer Cont’d
 Steps:
1. Take Chamfer command,
2. Select the first line,
3. Select the second line.
 To set chamfer distances:
1.Take Chamfer command,
2.Enter d (Distances),
3.Enter the first chamfer distance,
4.Enter the second chamfer distance,
5.Select the lines for chamfering.
94

14. The Explode Command
 The Explode Command is found at:
 Toolbar: Modify
 Dashboard:
 Pull down menu: Modify  Explode
 Keyboard: EXPLODE; Shortcut: Xp
 Steps:
1. Take Explode command,
2. Select Objects to explode, and Enter.
If you need to modify one or more objects
within a block separately, you can disassemble,
or explode, the block reference into its
component objects.
95

Block and attributes
96
 Blocks are drawings which can be
inserted into other drawings.
 Blocks are contained in the data of the
drawing in which they have been
constructed.
 Wblocks (written blocks) are saved as
drawings in their own right, but can be
inserted into other drawings if required.
 To creat a block first draw the component
you need and follow the steps:

Block and attributes
97
 To Make a Block of previously drawn object follow
the steps:
 Go to Menu bar – draw – block – make then
block definition dialog box appears. Then do the
following:
A. Enter name of the block in the Name field.
B. Click the Select objects button. The dialog disappears.
On drawing Window select the object. The dialog
reappears. OR Click the Pick Point button. The dialog
disappears. Click a point on the drawing to determine
its insertion point. The dialog reappears.
C. If thought necessary enter a description in the
Description field of the dialog.
D. Click the OK button. The drawing is now saved as a
block in the drawing

Insert Block
98
 To insert a Block which is previously created follow
the steps:
 Go to Menu bar – insert – block then insert
dialog box appears. Then do the following:
A. Enter name of the block in the Name field.
B. Specify insertion point select on screen if you want
to show the point on screen OR specify X,Y & Z
coordinate of the insertion point. The dialog
reappears.
C. Show the point where you want to insert the block
D. Click the OK button. The block is now inserted.

99
4. Text Annotation
and Dimensioning
in Auto CAD

4. Text Annotation and
Dimensioning in Auto CAD
CONTENTS
 Adding text to drawing;
 Adding Dimensions
 Setting preconditions for dimensioning
 Dimension style
 Primary units
 Dimensioning different features
100

Adding text to drawing
101
Text Command
 To create single-line text
1. Click Draw menu » Text » Single Line Text.
2. Specify the insertion point for the first
character.
3. Specify the height of the text.
4. Specify the text style and text font and color.
5. Specify a text rotation angle. You can enter
an angle value or use your pointing device.
6. Enter the text. At the end of each line, press
ENTER.
7. Click Ok to end the command.

102
 Dimensioning/Measurement is used
to tell us:
* How tall?
* How heavy?
* How many?
* How much?

1. Inch System
2. Metric (ISO)
3. Military (diverse)
4. Associations (also diverse)
103
Standards of Measurement:
 Measurement unit: click [U.S. military]
 Full name: click [U.S. military]
 Plural form: clicks means kilometer
 Category type: length
 Scale factor: 1000
 ›› SI unit: meter
 The SI base unit for length is the meter.
 1 meter is equal to 0.001 click [U.S. military].
 1 click = 1000 meters
Measurement set by an international
associations like: AMEC: The International
Association for Measurement and
Evaluation of Communication (also known
as)

Dimensions are applied to objects in a variety of styles:
1. Chain
i. Aligned
ii. Unidirectional
2. Tabular
3. Coordinate/Baseline
4. Ordinate
Dimensions styles
104

1. Overall:
 Width
 Depth
 Height
2. The actual size of features
(rounds, fillets, holes, arcs, etc.)
3. And where features are located
such as centers, angles,
etc.
Dimensions are used to show an object’s:-
106

107
There are several ways in which the dimensions tools
can be called.
1.From the Dimensions control panel in the
DASHBOARD
2.Click Dimension in the menu bar. Tools can be
selected from the drop-down menu which appears.
3.From the Dimension toolbar. The toolbar can be
called to screen with a right-click in any toolbar on
screen followed by a click on Dimension in the popup
menu which appears.
4.By entering an abbreviation for a dimension tool at
the command line.
Any one of these methods can be used when
dimensioning a drawing, but some operators may well
decide to use a combination of the four methods.
The Dimension tools

108
The Dimensioning Toolbar
 The dimensioning commands can be easily
accessed by:
 Right Click on an existing toolbar and
activate the dimensioning toolbar;
 Or, From the “pull down” menu
View
Toolbars

Creates linear dimensions.
Linear Dimensioning Aligned Dimensioning
Creates an aligned linear dimensions.

Radius dimensions measure the radii of arcs and circles with
optional centerlines or a center mark. If Text Placement is set
to Over the Dimension Line, with a leader, the dimension is
applied with a leader line.
Radius Dimensioning

Diameter dimensions measure the diameters of arcs and circles with optional
centerlines or a center mark. If Text Placement is set to Over the Dimension
Line, with a leader, the dimension is applied with a leader line.
Diameter Dimensioning
 DIMCENTER command creates the center mark or the centerlines of
circles and arcs.
Center Marks

Arc Length allows you to create length dimensions (see Figure
7–23) for an arc.
Arc Length Dimensioning

ANGULAR DIMENSION command allows to draw angular
dimensions using three points (vertex, point, point), between two
nonparallel lines, on an arc (between the two endpoints of the arc,
with the center as the vertex), and on a circle (between two points on
the circle, with the center as the vertex).
Angular Dimensioning

Baseline dimensioning is used to draw dimensions to multiple points from
a single datum baseline.
The first extension line origin of the initial dimension (it can be a linear,
angular, or ordinate dimension) establishes the base from which the
baseline dimensions are drawn.
AutoCAD automatically draws a dimension line/arc beyond the initial (or
previous baseline) dimension line/arc.
Baseline Dimensioning

Continue dimensioning is used for drawing a string of dimensions,
each of whose second extension line origin coincides with the next
dimension’s first extension line origin.
Continue Dimensioning

The DIMSPACE command allows you to specify the space
between the dimension lines of parallel linear or concentric arc
dimensions.
Dimension Space
Dimension Break
The DIMBREAK commnad allows you to create a break in a
dimension extension line where it crosses another line.

Quick Dimensioning is used to draw a string of dimensions
between all of the end and center points of the selected object(s).
Quick Dimensioning
MLEADER Command is used to to connect annotation to objects or
other features in the drawing.
Options include Leader Type, Leader Landing, Content Type,
Maxpoints, First Angle, and Second Angle.
Multileader

Add Leader Command is used to add leader line and arrow combinations
to an existing multileader.
Mutlileader Style Command is used to create or modify multileader style.
With a multileader style, you can specify formatting for landing lines, leader
lines, arrowheads, and content.
Multileader

 AutoCAD provides a special set of subcommands for the two
major methods of specifying tolerances: Lateral Tolerance and
Geometric Tolerance.
 Lateral tolerance draws the traditional symbols and text for
Limit, Plus or Minus (unilateral and bilateral), Single Limit,
and Angular tolerance dimensioning.
 Lateral tolerance is the range from the smallest to the greatest
that a dimension is allowed to deviate and still be acceptable.
 Lateral tolerance and its related settings are set in the
Dimension Style Manager dialog box (Tolerances tab).
Tolerances

Dimension Style Manager dialog box (Tolerance tab selection)

Geometric tolerance draws a Feature Control Frame for use in
describing standard tolerances according to the geometric
tolerance conventions.
Geometric tolerancing is applied to forms, profiles, orientations,
locations, and runouts. Forms include squares, polygons, planes,
cylinders, and cones.

Geometric Tolerance dialog box

Oblique Dimensioning
 OBLIQUE command allows to slant the extension lines of a linear
dimension to a specified angle.
 The dimension line will follow the extension lines, retaining its original
direction. This is useful for having the dimension stay clear of other
dimensions or objects in your drawing. It is also a conventional method of
dimensioning isometric drawings.
 AutoCAD allows to edit dimensions with MODIFY
commands and grip editing modes. Also, AutoCAD provides
two additional MODIFY commands specifically designed to
work on dimension text objects:
Dimedit
Dimtedit
Editing Dimension Text

DIMEDIT
 DIMEDIT command allows to replace the dimension text
with new text, rotate the existing text, move the text to a new
location, and if necessary, restore the text back to its home
position, which is the position defined by the current style.
 In addition, you also change the angle of the extension lines
(normally perpendicular) relative to the direction of the
dimension line.
 Available options include:
 Home selection returns the dimension text to its default
position.
 New selection change the original dimension text to the
new text.
 Rotate selection change the angle of the dimension text.
 Oblique selection adjusts the obliquing angle of the
extension lines for linear dimensions.

DIMTEDIT
 DIMTEDIT command is used to change the location of
dimension text (with the Left/Right/Home options) along the
dimension line and its angle (with the Rotate option).
 Available options include:
 Left selection cause the text to be drawn toward the left
extension line.
 Right selection cause the text to be drawn toward the right
extension line.
 Home selection returns the dimension text to its default
position.
 Angle selection changes the angle of the dimension text.

Dimension style Manager allows to create new styles, sets the current style,
modifies styles, sets overrides on the current style, and compares styles.
Each time a dimension is drawn it conforms to the settings of the Dimensioning
System Variables in effect at the time. The entire set of Dimensioning System
Variable settings can be saved in their respective states as a Dimension Style.
Dimension Styles
Dimension Style Manager

Create New Dimension Style dialog box
Modify Dimension Style dialog box – Lines selection

Various examples with Dimension and Extension Lines settings

Modify Dimension Style dialog box – Symbols and Arrows selection
Arrowhead types

Modify Dimension Style dialog box – Text selection
Dimensioning Text with various
Text appearance selections
Dimensioning Text with various
Text placement (horizontal) selection

Modify Dimension Style dialog box – Fit selection
Dimensioning examples with various Fit options
Dimensioning example with various
Text placement options

Modify Dimension Style dialog box – Primary Units selection
Dimensioning example with various
dimensioning unit formats
Dimensioning example with
prefix, suffix, and alternate units

Modify Dimension Style dialog box – Alternate Units selection
Modify Dimension Style dialog box
– Tolerances selection

 DIMOVERRIDE command change one of the features in a dimension
without having to change its dimension style or create a new dimension
style.
Overriding the Dimension Feature
 DIMENSION UPDATE command permits to make selected existing
dimension(s) conform to the settings of the current dimension style.
Updating Dimensions

 The DIMINSPECT dimension adds or removes
inspection information for a selected dimension.
 Inspection dimensions specify how frequently
manufactured parts should be checked to ensure
that the dimension value and tolerances of the
parts are within the specified range.
Inspecting Dimensions

137
5. Construct Isometric
and Introduction to 3D
Drawings

5. Construct Isometric and
Introduction to 3D Drawings
CONTENTS
 Construct isometric drawing
 Working in 3D;
 Solid modeling; Revolve tool bar, Extruded
toolbar
 Applying Boolean functions: Union ,
subtract, intersection…etc
 Visualization techniques (Rendering
Concepts)
138

I. ISOMETRIC DRAWING IN
AUTOCAD
139

 Isometric means equal measure
 All planes are equally or proportionately
shortened and tilted
 All the major axes (X, Y, Z) are 120 degrees
apart
140
CUBE
I. ISOMETRIC DRAWING IN
AUTOCAD

Cont…
• Making an Isometric Drawing
141
30o 30o
60o60o
Isometric Axis

I. Setting up isometric grid/snap
• The grid/snap style should be changed to
isometric snap
– Right click on grid button on status bar, choose
‘Settings…’
– Drafting setting window displaying Snap and
Grid tab is displayed
Isometric Drawing using Auto
CAD

Setting up isometric grid/snap
Rectangular
Isometric

II. Changing isoplane
• Changing the isoplane – left, top, right
– Cycle by pressing CTRL+E or F5 or
– Command: isoplane {enter}
Right Top Left

III. Drawing lines, circles and arc
• Isometric lines and non-isometric lines can be drawn
using line or polyline command
• Isometric circle can be drawn using ellipse command
– Draw ellipse > isocircle
• Isometric quarter circle and semi circle can be drawn
using ellipse arc command
– Draw ellipse arc > isocircle

Creating round corner
Before After
Draw ellipse
arc
Draw another
ellipse arc
Draw straight
line from
midpoint of
top arc to
midpoint of bottom arc
Trim Trim Trim

IV. Dimensioning
• Use aligned dimension for linear dimensioning
• Use quick leader for isocircle
Aligned dimension
Quick leader

To make dimension aligned with isometric axes, follow few steps as:
- Type DIMEDIT
- Type O for Oblique
- Select the dimension to be aligned, then Enter
- Specify the obliquing angle
For example, using the object above, for clockwise alignment such
as 90, type 30 for the angle, whereas for 100, type -30 for the angle
since anti-clockwise alignment.

Dimensioning for Isocircle
1. Select Quick leader icon
2. Select the circle, then extend the leader line to appropriate
direction, click, then make short extension in horizontal
direction, click, then type corresponding value (example:
R20) for the dimension.

Other useful tips
• Use COPY command with polar relative
coordinate system or OSNAP.
• Do not use OFFSET command.
• Set up LAYER before drawing.
• Use construction line as a guide
(recommended to use different colour)

II. 3D-MODELING USING
AUTOCAD
151

What is Modeling
 a process of constructing a virtual 3D graphics
object
 Modeling tools: creating and constructing
complex 3D models fast and easy.
 Rendering is a process of creating images
from graphics models.
152

A graphics model
 geometrical descriptions (particles, vertices,
polygons) and associated attributes (colors,
shadings, transparencies, materials)
 can be saved in a file using a standard (3D
model) file format.
153

3D Modeling Basics
1. Wireframe models
2. Surface models
3. Solid models
154

1. Wireframe Model
 Represents edge of actual
object
 Surfaces of object are not
defined
 Transparency and no
volume
 2D objects in 3D space
 Use Line, Circle, Arc
155

2. Surface Model
 Edges and surfaces are defined
 Object has volume but no mass
 Each surface is constructed individually
 Each surface is created / move to the
correct orientation w.r.t other surfaces
 Easier to visualize than wireframe
 Can be displayed in wireframe or hidden
view
  Draw / Surfaces…
 Command: _hide
156

3. Solid Model
 A complete computerized replica of the actual
object
 Complete surfaces, edges, interior features of
the object
 Object has volume and mass
 Can be displayed in wireframe or hidden view
 Constructing primitive shapes
Using Boolean operations to create composite solid
157

Creating solid models.
 A solid model is defined by volumes.
 Hierarchy of entities from low to high:
keypoints lines areas volumes.
 You cannot delete an entity if a higher-
order entity is attached to it.
158
Volumes
Areas
Lines &
KeypointsKeypoints
Lines
Areas
Volumes

Simple 3D Half-Spaces
 Sphere
 Cylinder
 Cone
 Torus
 Box
 Plane
 it splits space into two infinite half-spaces
 you can use an infinite cylinder and two planes to make a capped
cylinder
 You can also get a box from 6 planes…
159

Modeling Approaches
 Two approaches to creating a solid
model:
1. Top-down
2. Bottom-up
160

1. Top-Down Modeling
Approaches
 Top-down modeling starts with a definition of
volumes (or areas), which are then combined
in some fashion to create the final shape.
 The volumes or areas that you initially define are
called primitives.
 Primitives are located and oriented with the help
of the working plane.
 The combinations used to produce the final shape
are called Boolean operations.
161
add

Primitives
 2-D primitives: include rectangles, circles,
triangles, and other polygons.
 When you create a 2-D primitive, a modeling
tool usually defines an area, along with its
underlying lines and key points.
162

Primitives
 3-D primitives: blocks, cylinders, prisms,
spheres, and cones.
 When you create a 3-D primitive, a modeling
tool usually defines a volume, along with its
underlying areas, lines and key points.
163

2. Bottom-up modeling
Approaches
2. Bottom-up modeling starts with keypoints,
from which you “build up” lines, areas, etc.
 You may combine both methods.
164

Constructive Solid Geometry
(CSG) Techniques
Primitive Solids
 Draw / Solids…
 Box
 Cone
 Cylinder
 Extrude
 Revolve
 Sphere
 Torus
 Wedge
Boolean Operations
 Modify / Solid Editing
…
 Union
 Joins selected solids
 Subtract
 Subtract one set of solids
from another
 Intersect
 Create a solid of
intersection (common
volume) from the
selected solids
165
+

Common Operations
Drawing
Environments
 Metric unit orientation
 Set the drawing limit
 Set isometric
viewpoint
Primitive Solids and
2D Object
 Solid boxes
 Cylinders
 Rectangular
Object Modification
 Fillet
 Extrude
 Subtract
 Union
 Move
Dimensioning
166

Boolean Operations
 Boolean operations: combinations of
geometric entities: add, subtract, intersect,
divide, glue, and overlap, etc.
 The “input” to Boolean operations: geometric
entities, simple primitives or complicated
volumes imported from a CAD system.
167
add
Input entities Boolean operation Output entity(ies)

Boolean CSG Operations
 Union
 Addition, A Ú B
 Intersection
 A Ù B
 Difference
 Subtraction, A – B, A Ù not B
 Difference is not commutative
168

A more complicated example
 Difference of:
 Intersection of Sphere and Cube
 Union of 3 Cylinders
169
- =

Part Sample
(to be used in CAM section)
170
SW Isometric View

Part Sample
(to be used in CAM section)
171
Top View

Step 0: Setup the environment
 Set the environment at start
up
 Metric setting
 Viewing in 3D
 View / 3D Views / SW
Isometric
 Select common operations
from Toolbar
 View / Toolbars …
 Select Solid Editing, View
Point, Object Snap, Modify,
172

Step 1: Solid box
 Create solid box
at 0,0,0
 Define size of the
box: 50,50,15
 x, y, z coordinate
173

Step 2: Solid from 2D object
174
•Create separate object (2D
rectangular with the size 44,
44
•Round one corner: Fillet
(radius of 22)
•Create a solid object using
Extrude feature
•Draw / Solid / Extrude
•Height: 5; Taper: 0)

Step 3: Solid cylinders
175
•Create separate solid objects: 2 Cylinders:
• Diameter1 = 20; Diameter2 = 10; Height = 5
•Use Subtract command to create a hole (Modify / Solid editing…)

Step 4: Move Objects
 Move rounded
square object to
the base part
 Use object snap
to help locate the
positions
 Subtract small
box from the
bigger box
176

Step 5: Move objects
177
• Move a cylinder object to
an appropriate position
 Move at the base
of the cylinder to
22,22,10
• Combine (Union) 2
objects

Step 6: Round Corners
178
• Round the edges
using Fillet
(radius of 2)

Aragaw Gebremedhin auto cad lecture notes

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Aragaw Gebremedhin auto cad lecture notes