auto cad 1

E2004/1/1 INTRODUCTION TO CAD

INTRODUCTION TO CAD

OBJECTIVES

General Objective : To understand the function of CAD and how to begin using AutoCAD

Specific Objectives : At the end of the unit you should be able to:

Explain CAD.

Identify system requirement needed to run the CAD program.

List other CAD packages.

Explain the advantages of using CAD compared to conventional drawing.

Start AutoCAD to begin drawing.

Use menus, dialog box and toolbars.

Save and exit from AutoCAD drawing.

UNIT 1


1.0 DEFINITION OF CAD

CAD is an acronym for Computer Aided Design or Computer Aided Drafting. CAD allows you to accomplish design and drafting activities using a computer. We can use CAD to draw a building plan, circuit diagram, chart, 3D object and more.

Design is a broad field involving the process of making ideas into a real product or system. The design process requires repeated refinement of ideas until a solution results – a manufactured product or constructed system. Traditionally, design involves the use of sketches, drawings, renderings, 2-dimensional and 3-dimensional models, prototypes, testing, analysis, and documentation. Drafting is generally known as the production of drawing that is used to document a design for manufacturing or construction or to archive the design.

CAD is a tool that can be used to design and draft activities. CAD can be used to make “rough” ideas drawing, although it is more suited to create accurate finished drawing and rendering. CAD can be used to create a 2-dimensional or 3-dimensional computer model or system for further analysis and testing by other computer programs. In addition, CAD can be used to supply manufacturing equipment such as lathes, mills, laser cutter, or rapid prototyping equipment with numerical data to manufacture a product. CAD is also used to create the 2-dimensional documentation drawing for communicating and archiving the design.

INPUT 1aINPUT 1a


The tangible result of CAD activity is usually a drawing generated by a plotter or printer but can be a rendering of a model or numeric data in binary usually saved to magnetic or optical device such as a diskette, hard disk, tape or CD.

1.1 SYSTEM REQUIREMENT.

The following list consists of recommended hardware and software required for proper operation using CAD software.

Windows NT 3.51 or 4.0 or Windows 95 and the latest version. 32 MB of RAM. 50 MB of hard disk space. 10 MB additional RAM for each concurrent CAD session.

1.2 THE LIST OF OTHER CAD PACKAGE

There are many CAD packages that we can use to make a drawing. Each CAD package has an advantage to make drawing easier. Example of the packages are listed below;

AutoCAD Catiar AutoCADLT MasterCAM PSPICE AutoSketch

However, with the advancement of technology, CAD program has undergone changes and updated to meet the need of users.

1.3 ADVANTAGES OF USING AUTOCAD


Although there are many methods used to design and draft activities, CAD offers the following advantages over other methods in many cases:

Improving productivity, capability and accuracy. Faster editing, reviewing and designing. Improving quality of end product. Save storage for drawing.

1.3.1 Improving productivity, capability and accuracy.

Simple drawing created manually requires lesser time than larger and more complex drawings, particularly those involving similar shapes or repetitive operations. It may take some time to set up the first drawing and create some of the initial geometry, but any of the existing geometry or drawing setup can be easily duplicated in the current or for new drawings.

As CAD and the associated technology advance and software are becoming more interconnected, more productive developments are available. For example, it is possible to make a change to a 3-dimensional model that automatically causes a related change in the linked 2-dimensional engineering drawing. One of the main advantages of these technological advances is productivity.

When you draw with CAD system, the graphical elements, such as lines, arc, and circles are stored in the Cad file as a numeric data. CAD systems store that numeric data with great precision. For example, AutoCAD stores values with fourteen signification digits. The value 1 for example, is stored in scientific notation as the equivalent of 1.0000000000000. This precision provides you with the ability to create design and drawing that are 100% accurate for almost every case.

1.3.2 Faster editing, reviewing and designing.

Making changes to a CAD file known as editing is generally much faster than making changes to a traditional manual drawing. Since all the graphics elements in a CAD drawing are stored, only the affected components of the design or drawing need to be altered, and the


drawing can be plotted or printed again or converted to other formats. It can save our time to produce a new drawing.

1.3.3 Improving quality of end product.

The quality of end product is improved because during the development, we use accurate measurement without any confusion.

1.3.4 Save of storage With conventional method we use drawing paper as a media to save our file. If we have lot of drawing, more space is needed. This storage problem can be solved by using CAD drawing. We just need an electronic storage element such as hard disk or diskette to save a thousand drawing file.

As a student, learning AutoCAD, as opposed to learning another CAD software product, give you a higher probability of using your skills in industry. Likewise, there are employers who use AutoCAD than any other single CAD system. In addition, learning AutoCAD is a first CAD system gives you a good foundation for learning other CAD packages because many concepts and commands introduced by AutoCAD are utilized by other systems. In some cases, an AutoCAD feature becomes industry standards. The .DXF file format, for example, was introduced by AutoDesk and has become an industry standard for CAD file conversion between systems.


ACTIVITY 1a

FILL IN THE BLANK.

1.1 What is the definition of CAD? List its main function.___________________________________________________________________________________________________________________________________________________________________________________________________

1.2 List all the CAD packages that you know of.___________________________________________________________________________________________________________________________________________________________________________________________________

1.3 List the advantages of using CAD compared to conventional methods.____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________


FEEDBACK TO ACTIVITY 1a

ANSWERS.

1.1 CAD is an acronym for Computer Aided Design or Computer Aided Drafting. CAD allows you to accomplish design and drafting activities using a computer. We can use CAD to draw a building plan, circuit diagram, chart, 3D object and more. (Refer to input 1a page 2 )

1.2 There are many CAD packages that we can use to make a drawing. Each CAD package has an advantage to make drawing easier. Example of the packages are listed below;

a. AutoCADb. Catiarc. AutoCADLTd. MasterCAMe. PSPICEf. AutoSketch

1.3. Although there are many methods used to design and draft activities, CAD offers the following advantages over other methods in many cases:

Improving productivity, capability and accuracy. Faster editing, reviewing and designing. Improving quality of end product.


Save storage for drawing.

1.4 STARTING AUTOCAD

In this module, we use AutoCAD R14 package. We can use another AutoCAD version because the basic drawing is similar. Assuming that AutoCAD has been installed and configured properly for your system, you are ready to begin using AutoCAD. To start AutoCAD using any Windows, double click on the icon on the desktop as shown below.

Figure 1.1: AutoCAD R14 Icon

If the icon does not appear on the desktop, press the ‘Start’ button, highlight ‘Programs’, and search for ‘AutoCAD R14’ in the menu. From the list displayed, select ‘AutoCAD R14’.

INPUT 1bINPUT 1b


Figure 1.2: Start AutoCAD from Start button

1.4.1 Start Up Dialog Box

When you start AutoCAD, the ‘Start Up’ dialog box appears. This dialog box includes several tools to help you open an existing drawing or set up a new drawing.

Figure 1.3: Start Up dialog box

The following is the content of the instructions for the ‘Start Up’ dialog box as it explains the purpose of the first four buttons.

The button on the left determine how you begin a drawing


“ Use a Wizard ” - lead through setting up a drawing“ Use a Template ” - start a drawing based on the template“ Start from Scratch ”- begin drawing quickly using default

English or Metric settings“ Open a Drawing ” - Open an existing drawing

USE A WIZARD

If you want to set up a drawing using a dialog box, choose ‘Use a Wizard’. You can choose from two wizards: ‘Quick Setup’ and ‘Advanced Setup’.

‘Quick Setup.’

Choose the Quick Setup wizard to set up the drawing area and change settings, such as text height and snap spacing, to an appropriate scale. With the Quick Setup wizard, you establish basic settings that help define the units of measure and drawing area. These settings include the basic unit type (such as architectural, decimal, engineering, fractional, or scientific units) to be used for display and plotting.

You also specify the width and length of the drawing area, and thereby establish the drawing's boundaries, called limits. The area within these limits defines the final plotted sheet size. After you accept the settings, the drawing session will begin.

Step 1: Units

Select the format in which you want to display units of measure. Select the format in which you want to enter and display coordinates and measurements. Several measurement styles are available in AutoCAD. Two of them, Engineering and Architectural, have a specific base unit (inches) assigned to them. You can choose from other measurement styles that can represent any convenient unit of measurement:


Decimal. - Select to display measurements in decimal notation. Engineering. - Select to display measurements in feet and decimal

inches. Architectural.- Select to display measurements in feet, inches, and

fractional inches. Frictional - Select to display measurements in mixed number

(integer and fractional) notation. Scientific. - Select to display measurements in scientific notation

(numbers expressed in the form of the product of a decimal number between 0 and 10 and a power of 10).

Figure 1.4 : Quick Setup box for step 1.

Step 2: Area

Enter the approximate width and length in full-scale units of what you plan to draw. This limits the area of the drawing covered by grid dots when the grid is turned on. It also adjusts several default settings, such as text height, linetype scaling, and snap distance, to convenient values. You can also adjust these settings, individually, from the Format menu later in the drawing session.


Figure 1.5 : Quick Setup box for step 2.

‘Advanced Setup.’

Choose the Advanced Setup wizard to set up the drawing area and change settings, such as text height and snap spacing, to an appropriate scale. You can also establish basic layout features.

Step 1: Units

Select the format in which you want to enter and display coordinates and measurements. Several measurement styles are available in AutoCAD. Two of them, Engineering and Architectural, have a specific base unit assigned to them (inches). You can choose from other measurement styles that can represent any convenient unit of measurement:


Figure 1.6: Advanced Setup box for step 1

The precision that you specify controls the number of decimal places or fractional size to which you want linear measurements displayed.

Step 2: AnglesSelect the format in which you want to enter and display angles:Decimal Degrees. Select to enter and display partial degrees as decimals.Deg/Min/Sec. Select to enter and display partial degrees as minutes

and seconds.Grads. Select to enter and display angles as grads.Radians. Select to enter and display angles as radians.Surveyor. Select to enter and display angles in surveyor units.

Figure 1.7: Advanced Setup for step 2


Step 3: Angle Measure

Select the direction of the zero angles for the entry of angles:

Figure 1.8: Advanced Setup box for step 3.

East. Select to specify the compass direction east as the zero angle.North. Select to specify the compass direction north as the zero angle.West. Select to specify the compass direction west as the zero angle.South. Select to specify the compass direction south as the zero angle.Other. Select to specify a direction different from the points of the compass

as the zero angle.

Step 4: Angle Direction

Select the direction to enter and display positive angle values: counterclockwise or clockwise.


Figure 1.9: Advanced Setup Box for step 4

Step 5: Area

Enter the approximate width and length of what you plan to draw in full-scale units. This limits the area of the drawing covered by grid dots when the grid is turned on. It also adjusts several default settings, such as text height, linetype scaling, and snap distance, to convenient values. You can also adjust these settings, individually, from the Format menu later in the drawing session.

Figure 1.10 : Advanced Setup box for Step 5


Step 6: Title Block

Select the description of an AutoCAD drawing file of a title block to insert as a symbol in your new drawing. You can add or remove drawing files of title blocks from the list with the ‘Add and Remove’ buttons.

Figure 1.11: Advanced Setup box for Step 6

Step 7: LayoutSelect Yes to use advanced paper space layout capabilities in

AutoCAD. Paper space is often used to create complex multiple-view drawings. Select No to use model space only. If you select ‘Yes’ to use paper space, you have three choices of where you want to begin working.

Figure 1.12: Advanced Setup box for step 7


USE A TEMPLATE.

If you want to start a drawing based on a template drawing, choose Use a Template.

Figure 1.13 : Create New Drawing using Template

Template Drawing is a drawing file that you can use as a starting point for new drawings. It stores all the settings for a drawing and may also include predefined layers, dimension styles, and views. Template drawings are distinguished from other drawing files by a different file extension, .dwt. They are normally kept in the template directory. Several template drawings are included with AutoCAD. You can make additional template drawings by changing the extensions of drawing file names to have a .dwt extension.

START FROM SCRATCH

If you want to begin drawing quickly using default English or metric settings, choose Start from Scratch.


Figure 1.14 : Create New Drawing box using Start From Scratch

From the Select Default setting field, we can choose either English or Metric setting.

English - Unit measurement is in traditional setting ( Inches )Metric - Unit measurement is in standard setting ( MM )

1.5 AUTOCAD R14 DRAWING SCREEN

Below are the standard screens for AutoCAD R14. We can adjust the screen weather to add or remove some toolbar or change the toolbar or resize the screen arrangement. In a standard AutoCAD R14, we can see the ‘Menu Bar’, ‘Toolbar’, ‘Layer Status Windows’, ‘Command Line’, ‘Status Line’, ‘Drawing Area’ and ‘Cursor Pointing’.


Figure 1.15 : AutoCAD Drawing Screen

ToolbarsAutoCAD R14 provides a variety of toolbars. Each toolbar contains a number of icon buttons that can be selected to invoke command.

Menu BarsThese menus provide an alternative method of accessing command and dialog boxes other than the Command Prompt or a toolbars button. They are termed pull-down menus because when you choose one with your left mouse button, the menu is displayed beneath its title, as if you were pulling the menu down from its title.

Layer Status Window Menu Bar

Drawing Area

Command Line

Crosshair Cursor

Toolbars

Status Line


Figure 1.16: Pull-Down Menu

Command LineThe command line is a docked or floating window where you can enter names or command and where AutoCAD displays prompts and messages.

Layer Status WindowLayer status window shows the current layer setting.

Status LineThe status line is a set of informative words or symbols that gives the status of the drawing aids. The following drawing aids can be toggled on or off by double-clicking on the desired word or by using Function keys or Ctrl key sequences.

1.6 GETTING TOOLBARS FROM PULL DOWN MENUWe can use toolbars to perform the desired command like ‘line’, ‘circles’ and other. By default there are four toolbars that appear in the AutoCAD screen. To display another toolbar, we can access the ‘Toolbars’ dialog box in the following ways;

Toolbar : ‘Right clicking any currently visible toolbar’Menu : View>ToolbarCommand : toolbar

Pull-Down Menu


The toolbar dialog box is displayed, as shown in the following figure:

Figure 1.17: Toolbar Setting Box

Choose any of the toolbar checkboxes displays the toolbar. The toolbar can then be moved anywhere in the application window by selecting the title bar and dragging the toolbar to a location.

1.7 SAVING FILE AND EXIT FROM AUTOCADAutoCAD uses different file saving command that protect your work by storing the existing drawing status to a named file in a directory. Saving your work is very important because if there is a power failure, all of your work saved prior to the problem will be usable.Various file saving commands are used to store drawing information. These command include SAVE, SAVE AS and QSAVE.

The SAVE command saves the drawing with the current filename or a specified name when saved the first time. We can get the command with the following ways

Menu : File>SaveCommand : SAVE

The SAVE AS command saves unnamed drawings with a filename, or saves the current drawing with a different name.


The QSAVE command saves currently named drawing one at a time without requesting a filename

Toolbar : Menu : File > SaveCommand : QSAVE

Use the following steps to save unnamed drawing

1. Toolbars : ( If we click this button for the first time, the Save Drawing As box will appear )

Menu : File> SaveCommand : SAVE

2. When the Save Drawing As appears, enter the name of the drawing in file name field. ( the file extension is not required)

Figure 1.18: ‘Save Drawing As’ box

After saving the file we can continue or exit the AutoCAD application. To exit from AutoCAD, use the following method;1. Click at the very right upper button of the screen

Menu : File>Exit Command : EXIT


ACTIVITY 1b

EXERCISES.

1.4 Starting AutoCAD by clicking the ‘AutoCAD R14 shortcut icon’ or ‘AutoCAD R14’ from the ‘programs menu’. If the start up dialog box appears, select ‘start from scratch’. Choose ‘English’ as the default setting, and click the ‘OK’ button. At the AutoCAD screen, name toolbars and menus when we moved the cursor around the screen without clicking.

1.5 Draw a line by typing ‘L’ at the ‘command line’. Click the cursor at the drawing area and move it to other point. Save your drawing and name it ‘exercise1’.

1.6 Exit AutoCAD by selecting the exit option from the ‘pull down menu’ or click the upper right button on the screen. Repeat the open and exit steps until you are confident with the procedure.

1.7 Try to start a new drawing with another set up ‘use a wizard’ and ‘use a template’

1.8 Using the Toolbars Dialog Box

At the Command prompt enter toolbar. The toolbars dialog box is displayed, as shown in the figure 1.17

In the Toolbars list box, check the modify 11 checkbox. The Modify 11 toolbar is displayed in the drawing windows as a floating toolbar

Now you will change the Modify 11 toolbar from a floating toolbar to a docked toolbar. To do this, place the cursor on the title bar on the toolbar, then press and hold the left mouse button


Drag the modify 11 toolbar to the docking region under the Object Properties toolbar, then release the left mouse button. When the toolbar is docked, the title bar name is no longer displayed.

In the Toolbar dialog box, clear the Modify 11 Checkbox. The Modify 11 toolbar is no longer displayed.

Choose Close to close the Toolbars dialog box.


FEEDBACK TO ACTIVITY 1b

Once you have completed this activity, please refer to your lecturer for further comments.


ANSWER ALL THE QUESTIONS BELOW

QUESTION 1-1a) How many ways can you start an AutoCAD drawing session? What

are they?

b) How can you disable and reactivate the display of the Start Up dialog box?

c) Describe the AutoCAD application window and explain each window area.

Layer Status Window

Menu Bar

Command Line

Crosshair Cursor

Toolbars

Status Line


d) How many way provided by AutoCAD to begin drawing. Explain.

e) What is the purpose of ‘Advanced Setup’ and list all the steps to draw by using ‘Advanced Setup’ format.


FEEDBACK TO SELF-ASSESSMENT

ANSWERS

QUESTION 1-1a) Two ways to start AutoCAD

i. Click on icon AutoCAD R14 on the Desktopii. Press Start>Programs>AutoCAD R14

b) We can activate using the following waysPull-down menu : File>New

Toolbar : We can disable by clicking cancel button at start up dialog box

and upper right click at the start up dialog box.c)


Toolbars

Layer Status Window Menu Bar

Drawing Area

Command Line

Crosshair Cursor

Toolbars

Status Line


AutoCAD R14 provides a variety of toolbars. Each toolbar contains a number of icon buttons that can be selected to invoke command.

Menu BarsThese menus provide an alternative method of accessing command and dialog boxes other than the Command Prompt or a toolbars button. They are termed pull-down menus because when you choose one with your left mouse button, the menu is displayed beneath its title, as if you were pulling the menu down from its title.

Command LineThe command line is a docked or floating window where you can enter names or command and where AutoCAD displays prompts and messages.

Layer Status WindowLayer status window shows the current layer setting.

Status LineThe status line is a set of informative words or symbols that gives the status of the drawing aids. The following drawing aids can be toggled on or off by double-clicking on the desired word or by using Function keys or Ctrl key sequences.

d) There are 4 ways to begin the drawing. They are:“ Use a Wizard ” - lead through setting up a drawing“ Use a Template ” - start a drawing based on the template“ Start from Scratch ”- begin drawing quickly using default

English or Metric settings“ Open a Drawing ” - Open an existing drawing

e) ‘Advanced Setup.’


Choose the Advanced Setup wizard to set up the drawing area and change settings, such as text height and snap spacing, to an appropriate scale. You can also establish basic layout features.

Step 1 : UnitsStep 2 : AnglesStep 3 : Angle MeasureStep 4 : Angle DirectionStep 5 : AreaStep 6 : Title BlockStep 7 : Layout

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