AUTO CAD 2005 basic level course chapter 1

INTRODUCTION

            AutoCAD is a well known computer program which provide helps in engineering design processes. It was first launched on 1982 by Autodesk Corp. but with a very minimum facilities. Lately AutoCAD is having a phenomenal major developments in following its surrounding technology developments. Especially the development in information technology which used to gain enhancements in data communications via computer networks and even over the internet.

I.1 The Advantages of AutoCAD

            As one of the world best selling CAD software, most of AutoCAD’s users thought that it gives so many advantages like follows :

1. Accuracy, high precision level
2. Time efficient in design creation and editing, mass design processes capability
3. Almost unlimited workplane, the ability of multiple documents interface
4. No accidental or editing scratches in design revision processes
5. Scale flexibility, drafting scale can be customized as necessary without changing object measurement partly.
6. The easiness in documentations, easy file saving and opening, conversion into other software document formats, also we can open our AutoCAD’s file in other CAD softwares.

I.2 Whats New in AutoCAD 2005

The following information summarizes what's new in AutoCAD 2005.

Drawing Output

1. Named sheet selections. Specify sheets to include in a named set that can be reused whenever you plot, transmit, or archive.
2. Electronic transmittals. Package an entire sheet set or a named selection of sheets for electronic transmittal.

Plot and Publish Tools

1. Background plotting. Plot an entire sheet set or a named selection of sheets while you continue to work. Monitor or cancel the plot job using a new plot icon displayed in the status tray.
2. Simplified Plot dialog box. Use the streamlined Plot dialog box in its unexpanded state to update the settings you change most frequently. Expand the dialog box to access more advanced settings.
3. Page setup enhancements. Create and save page configurations for sheet sets as well as for individual drawings. Use the new Page Setup Manager to import named page setups from other drawings.
4. Enhanced DWF format. Plot to a Design Web Format (DWF) to share data-rich drawings, maps, and models while ensuring the integrity of the data. Anyone with a DWF viewer, such as the free Autodesk DWF Viewer (formerly Autodesk Express Viewer), can display accurate design information.
5. Enhanced publishing. Publish one or more sheets without having to save them first. Include a plot stamp and preview the output before you start. Publish multisheet DWF files or multiple single-sheet DWF files. Apply password protection to ensure drawing security.

Tool Palette Enhancements

1. Tools by example. Create new tools by dragging objects such as dimensions, multiline text, gradients, blocks, and hatches from your drawing area onto a tool palette.
2. Command tools. Set up frequently used commands as tools and organize them on tool palettes. Customize them by setting properties such as layer and linetype.
3. Tool palette organization. Use tool palette groups to organize tool palettes into logical sets. Then save screen space by displaying only the tool palette group you need.

Drafting Tools

1. Intuitive table creation. Instead of drawing lines to create tables, create table objects using a dialog box. Specify the number and size of rows and columns, and add text and fields to the cells. Save table configurations to reuse later.
2. Fields that can be updated. Insert a field into any text except tolerances to display drawing data that you expect to change, such as a date or sheet number. When the information changes, the value of the field is updated.
3. Display of overlapping objects. Use the tools on the Draw Order toolbar to change the display and plotting order of overlapping objects without regenerating. Assign a draw order to a hatch pattern in advance. Specify that text and dimensions always display in front of other objects.
4. Markups for design review. Use the electronic markup utility to help your project team or customers provide feedback about your work, even if they do not have AutoCAD.
5. Backgrounds for multiline text and dimensions. Add an opaque fill or background mask to emphasize multiline text and dimension text in a visually complex drawing.
6. New notation symbols. Insert symbols for commonly used notations such as angle, delta, property line, and centerline from the shortcut menu of the Multiline Text Editor.
7. Hatch object trim. A hatch object now can be trimmed like other objects.
8. Hatch tolerance for areas with gaps. Use HPGAPTOL to set the maximum size of gaps that can be ignored when objects serve as a hatch boundary.
9. Interchangeable commands for editing attributes. You no longer need know the text type before choosing an editing command. Both the DDEDIT and ATTEDIT commands can be used to edit attributes.
10. Reverse arcs and calligraphy style for revision clouds. Choose a calligraphy style when creating revision clouds. Reverse the direction of the arcs for revision clouds converted from both open and closed objects.
11. Backgrounds for 3D scenes. When working with three dimensional objects, you can add a solid color or gradient background, or attach a raster image as a background to the scene. The background is displayed when you use SHADEMODE, as well as when you render the scene.
12. Control of display as you adjust clipping planes. In the Adjust Clipping Planes window, pan and zoom the displayed objects. Use the Reset option on the shortcut menu to zoom to the extents of the drawing.
13. Vertical text. Set text styles that have a vertical orientation by specifying font names that are preceded by the @ symbol.

I.3 Launching AutoCAD 2005

You can start AutoCAD in the following ways:

1. Desktop shortcut icon. When you install AutoCAD, an AutoCAD 2005 shortcut icon is placed on your desktop automatically, unless you cleared that option during installation. Double-click the AutoCAD 2005 icon to start AutoCAD.
2. Start menu. On the Start menu (Windows), click All Programs (or Programs) Autodesk à AutoCAD 2005 à AutoCAD 2005.
3. Location where AutoCAD is installed. If you have power user or administrator permissions, you can run AutoCAD in the location where you installed it (for example, c:\Program Files\AutoCAD 2005\acad.exe). If you are a limited user, you must run AutoCAD from the Start menu or from the desktop shortcut icon. If you want to create a custom shortcut, make sure that the Start In directory for the shortcut points to a directory where you have write permission.

I.4 AutoCAD 2005 System Requirements

Before you install AutoCAD^® on a stand-alone computer, make sure that your computer meets the minimum system requirements. See the following table for hardware and software requirements.

Hardware and software requirements
Hardware / Software	Requirement	Notes
Operating system	Windows® XP Professional Windows XP Home Windows XP Tablet PC Windows 2000	It is recommended that non-English language versions of AutoCAD be installed on an operating system with a user interface language that matches the code page of the AutoCAD language. A code page provides support for character sets used in different languages. You must have administrator permissions or be granted elevated permissions by your system administrator to install AutoCAD.
Web browser	Microsoft Internet Explorer 6.0 with Service Pack 1 (or later)
Processor	Pentium III or later 800 Mhz
RAM	256 MB
Video	1024 x 768 VGA with True Color (minimum)	Requires a Windows-supported display adapter.
Hard disk	Installation 300 MB
Pointing device	Mouse, trackball, or other device
CD-ROM	Any speed (for installation only)
Optional hardware	Open GL-compatible 3D video card Printer or plotter Digitizer Modem or access to an Internet connection Network interface card	The OpenGL driver that comes with the 3D graphics card must have the following: Full support of OpenGL or later. An OpenGL Installable Client Driver (ICD). The graphics card must have an ICD in its OpenGL driver software. The "miniGL" driver provided with some cards is not sufficient for use with AutoCAD.

I.5 User Interface

            After AutoCAD 2005 launched we can see a user interface as follows :

You can use several menus, shortcut menus, tool palettes, and toolbars for access to frequently used commands, settings, and modes.

1. Tool Palettes : Tool palettes are tabbed areas within the Tool Palettes window that provide an efficient method for organizing, sharing, and placing blocks and hatches. Tool palettes can also contain custom tools provided by third-party developers.

5. Toolbars : Use buttons on toolbars to start commands, display flyout toolbars, and display tooltips. You can display or hide, dock, and resize toolbars.
6. The Menu Bar : Display pull-down menus from the menu bar using one of several methods. You can also specify alternate menus.
7. Shortcut Menus : Display a shortcut menu for quick access to commands that are relevant to your current activity. It displayed when we right click our pointing device (mouse) on the drawing area or when selecting an object.
8. The Command Line : Besides of using toolbars, palettes and shortcuts we can also type our command directionally to the command line which are located on the lower parts of the user interface.

I.6 Start a Drawing

I.6.1 Start-Up Dialog

There are four main options when we start to create new file :

1. Open a Drawing

We can also start a new file or drawing by using a file that we have created before.

2. Start a Drawing from Scratch

A quick way to begin a new drawing is to start from scratch, which starts a drawing that uses settings from a default drawing template file.

3. Use a Setup Wizard

A setup wizard establishes basic drawing settings step by step.

4. Use a Template File to Start a Drawing

A drawing template file contains standard settings. Select one of the template files supplied, or create your own template files.

I.6.2 Preparing Drawing Area

Units

Set the Units Format

You can specify the display format of the unit. Depending on what you specify, you can enter coordinates in decimal form, fractional form, degrees, or other notation. To enter architectural feet and inches format, indicate feet using the prime symbol ('), for example, 72'3. You don't need to enter quotation marks (") to specify inches.

You can set the unit type and precision in the Quick Setup wizard, the Advanced Setup wizard, or the Units Control dialog box. These settings control how your coordinate, offset, and distance entries are interpreted, and how coordinates and distances are displayed.

You can enter three-dimensional coordinates in the same input formats as two-dimensional coordinates: scientific, decimal, engineering, architectural, or fractional notation.

Report formats:           (Examples)

  1.  Scientific              1.55E+01

  2.  Decimal                15.50

  3.  Engineering          1'-3.50"

  4.  Architectural        1'-3 1/2"

  5.  Fractional             15 1/2

Base Angle

Sets the direction of the zero angle. The following options affect the entry of angles, the display format, and the entry of polar, cylindrical, and spherical coordinates.

·         East

Specifies the compass direction east (the default).

·         North

Specifies the compass direction north.

·         West

Specifies the compass direction west.

·         South

Specifies the compass direction south.

·         Other

Specifies a direction different from the points of the compass.

·         Angle

Specifies a value for the zero angle when Other is selected. You can specify the angle by entering a value.

·         Pick an Angle Button

Defines the zero angle in the graphics area based on the angle of an imaginary line that connects any two points you specify with the pointing device. Available only when Other is selected.

Angle

Specifies the current angle format and the precision for the current angle display.

·         Type

Sets the current angle format.

·         Precision

Sets the precision for the current angle display.

AutoCAD uses the following conventions for the various angle measures:

-          Decimal degrees appear as decimal numbers, grads appear with a lowercase g suffix, and radians appear with a lowercase r suffix. The degrees/minutes/seconds format uses d for degrees, ' for minutes, and " for seconds; for example:

123d45'56.7"

-          Surveyor's units show angles as bearings, using N or S for north or south, degrees/minutes/seconds for how far east or west the angle is from direct north or south, and E or W for east or west; for example:

N 45d0'0" E

The angle is always less than 90 degrees and is displayed in the degrees/minutes/seconds format. If the angle is precisely north, south, east, or west, only the single letter representing the compass point is displayed.

·         Clockwise

Calculates positive angles in the clockwise direction. The default direction for positive angles is counterclockwise.

When AutoCAD prompts for an angle, you can point in the desired direction or enter an angle regardless of the setting specified for Clockwise.

Limits

Used to define the size of workplane that we use to make a drawing.

limits (or 'limits for transparent use)

Specify lower left corner or [ON/OFF] <current>:  Specify a point, enter on or off, or press ENTER

Specify upper right corner <current>:  Specify a point or press ENTER

I.6.3 Saving a File

You save drawing files for later use just as you do with other Microsoft Windows applications. AutoCAD also provides automatic saving, backup files, and other options for saving.

When you are working on a drawing, you should save it frequently. Saving protects you from losing work in the event of a power failure or other unexpected event. If you want to create a new version of a drawing without affecting the original drawing, you can save it under another name.

The file extension for AutoCAD drawing files is .dwg, and unless you change the default file format in which drawings are saved, drawings are saved in the latest drawing-file format. This format is optimized for file compression and for use on a network.

Save Your Drawing Automatically

If you turn on the automatic saving option, your drawing is saved at specified time intervals. By default, files saved automatically are temporarily assigned the name filename_a_b_nnnn.sv$. Filename is the current drawing name, a is the number of open instances of the same drawing file in the same AutoCAD session, b is the number of open instances of the same drawing in different sessions of AutoCAD, and nnnn is a random number generated by AutoCAD.

These temporary files are automatically deleted when a drawing closes normally. However, the files remain in the event of a program failure or a power failure. To recover a previous version of your drawing from the automatically saved file, rename the file using a .dwg extension in place of the .sv$ extension.

Use Backup Files

If you turn on automatic backups, AutoCAD saves the previous version of your drawing files to a file with the same name and a .bak file extension. To recover the previous version of your drawing from a backup file, rename the file using a .dwg extension.

Save Part of a Drawing File

If you want to create a new drawing file from part of an existing drawing, you can use BLOCK or WBLOCK. With either command, you can select objects or specify a block definition in your current drawing and save them in a new drawing file. You can also save a description along with the new drawing.

Save to a Different Type of Drawing File

You can save a drawing to an earlier version of the drawing format (DWG) or drawing interchange format (DXF), or save a drawing as a template file. Choose the format from Files of Type in the Save Drawing As dialog box.

I.6.4 Opening a File

To open an existing AutoCAD drawing, you can use Open on the File menu to display the Select File dialog box.

You can also open drawings by dragging them from Windows Explorer into AutoCAD. If you drop one or more drawings anywhere outside the drawing area—for example, the command line or the blank space next to the toolbars—AutoCAD opens the drawings. However, if you drag a single drawing into the drawing area of an open drawing, the new drawing is not opened but inserted as a block reference.

You can double-click a drawing in Windows Explorer to launch AutoCAD and open the drawing. If AutoCAD is already running, the drawing opens in the current session rather than in a second session.

If you organize drawings using the sheet set feature, you can use the Sheet Set Manager to locate and open the drawings in the sheet set.

Check Drawing Authenticity

If the DWGCHECK system variable is set to On (1), AutoCAD checks the DWG file format and displays an alert box if

• The drawing file format is AutoCAD LT 97 or later or AutoCAD Release 14 or later and
• The file was last saved by a program other than AutoCAD LT 97 or later or AutoCAD Release 14 or later

To avoid checking for file authenticity each time you open drawings, clear the Always Show This Dialog Box option when the alert is displayed. Alternatively, you can set DWGCHECK to Off (0).

I.7 Tools to Help on Creating a Drawing

I.7.1 Snap & Grid

Snap mode restricts the movement of the crosshairs to intervals that you define. When Snap mode is on, the cursor seems to adhere, or "snap," to an invisible rectangular grid. Snap is useful for specifying precise points with the arrow keys or the pointing device.

The grid is a rectangular pattern of dots that extends over the area you specify as the grid limits. Using the grid is similar to placing a sheet of grid paper under a drawing. The grid helps you align objects and visualize the distances between them. The grid is not plotted. If you zoom in or out of your drawing, you may need to adjust grid spacing to be more appropriate for the new magnification.

Change Grid and Snap Spacing

As you work, you can turn Grid and Snap mode on and off, and you can change the grid and snap spacing.

Snap spacing does not have to match grid spacing. For example, you might set a wide grid spacing to be used as a reference but maintain a closer snap spacing for accuracy in specifying points.

You can set the parameters for snap & grid from drafting setting dialog box. As you see above.

I.7.2 Polar

When you are creating or modifying objects, you can use polar tracking to display temporary alignment paths defined by the polar angles you specify. You can use PolarSnap™ to snap to specified distances along the alignment path. For example, in the following illustration you draw a two-unit line from point 1 to point 2, and then draw a two-unit line to point 3 at a 45-degree angle to the line. If you turn on the 45-degree polar angle increment, AutoCAD displays an alignment path and tooltip when your cursor crosses the 0 or 45-degree angle. The alignment path and tooltip disappear when you move the cursor away from the angle.

As you move your cursor, alignment paths and tooltips are displayed when you move the cursor near polar angles. The default angle measurement is 90 degrees. Use the alignment path and tooltip to draw your object. You can use polar tracking with Intersection and Apparent Intersection object snaps to find where a polar alignment path intersects another object.

Note :  Ortho mode restricts the cursor to horizontal or vertical (orthogonal) axes. Because you cannot have Ortho mode and polar tracking turned on at the same time, AutoCAD turns polar tracking off when you turn on Ortho mode. If you turn polar tracking back on, AutoCAD turns Ortho mode off. Similarly, if you turn PolarSnap on, grid snap is turned off automatically.

Specify Polar Angles (Polar Tracking)

You can use polar tracking to track along polar angle increments of 90, 60, 45, 30, 22.5, 18, 15, 10, and 5 degrees, or you can specify other angles. The following illustration shows the alignment paths displayed as you move your cursor 90 degrees with the polar angle increment set to 30 degrees.

The orientation of 0 depends on the angle you set in the Drawing Units dialog box ( UNITS). The direction of snap (clockwise or counterclockwise) depends on the units direction you specify when setting units of measurement.

Specify Polar Distances (PolarSnap)

PolarSnap restricts cursor movement to increments of a polar distance you specify. For example, if you specify a length of 4 units, the cursor snaps from the first point specified to lengths of 0, 4, 8, 12, 16, and so on. As you move your cursor, a tooltip indicates the nearest PolarSnap increment. To restrict point entry to polar distances, both polar tracking and Snap mode (set to PolarSnap) must be on.

I.7.3 Ortho

In the illustration, a line is drawn using Ortho mode. Point 1 is the first point specified, and point 2 is the position of the cursor when the second point is specified.

AutoCAD uses Ortho mode when you specify an angle or distance by means of two points using a pointing device. In Ortho mode, cursor movement is constrained to the horizontal or vertical direction (relative to the UCS) and the current grid rotation angle. AutoCAD ignores Ortho mode in perspective views.

AutoCAD defines horizontal as being parallel to the X axis of the UCS and vertical as being parallel to the Y axis. ORTHO adjusts to the current snap rotation regardless of the UCS.

I.7.4 Object Snap (Osnap)

An object snap mode specifies a snap point at an exact location on an object. OSNAP specifies running object snap modes, which remain active until you turn them off.

Running object snap modes can be toggled on and off with the Osnap button on the status bar. You can use the TAB key to cycle through available object snaps. Running object snap settings are stored with the drawing.

Object Snap Modes

Specify one or more object snap modes by entering the first three characters of the name. If you enter more than one name, separate the names with commas. ENDpoint CENter TANgent MIDpoint NODe NEArest INTersection QUAdrant PARallel EXTension INSertion APParent Intersection PERpendicular For a description of each of these object snap modes, see the Object Snaps tab of the Drafting Settings dialog box. The -OSNAP command also presents the following additional options: QUIck Snaps to the first snap point found. Quick must be used in conjunction with other object snap modes. NONe Turns off object snap modes.

I.8 Coordinate System

When a command prompts you for a point, you can use the pointing device to specify a point, or you can enter a coordinate value on the command line. You can enter two-dimensional coordinates as either Cartesian (X,Y) or polar coordinates.

Cartesian and Polar Coordinates

A Cartesian coordinate system has three axes, X, Y, and Z. When you enter coordinate values, you indicate a point's distance (in units) and its direction (+ or -) along the X, Y, and Z axes relative to the coordinate system origin (0,0,0).

In 2D, you specify points on the XY plane, also called the construction plane. The construction plane is similar to a flat sheet of grid paper. The X value of a Cartesian coordinate specifies horizontal distance, and the Y value specifies vertical distance. The origin point (0,0) indicates where the two axes intersect.

Polar coordinates use a distance and an angle to locate a point. With both Cartesian and polar coordinates, you can enter absolute coordinates based on the origin (0,0), or relative coordinates based on the last point specified.

Another method of entering a relative coordinate is by moving the cursor to specify a direction and then entering a distance directly. This method is called direct distance entry.

You can enter coordinates in scientific, decimal, engineering, architectural, or fractional notation. You can enter angles in grads, radians, surveyor's units, or degrees, minutes, and seconds. You specify the unit style in the Units Control dialog box.

Absolute coordinate values are based on the origin (0,0), where the X and Y axes intersect. Use absolute coordinates when you know the precise X and Y values of the point. For example, the 3,4 specifies a point 3 units along the X axis and 4 units along the Y axis from the origin.

Relative coordinates are based on the last point entered. Use relative coordinates when you know the location of a point in relation to the previous point. To specify relative coordinates, precede the coordinate values with an @ sign. For example, @3,4 specifies a point 3 units along the X axis and 4 units along the Y axis from the last point specified.

For example, to draw a line beginning at an X value of –2, a Y value of 1, and an endpoint at 3,4, make the following entries on the command line:

Command:  line

From point:  –2,1

To point:  3,4

  

AutoCAD locates the line as follows:

The following example draws a line whose endpoint is 5 units in the X direction and 0 units in the Y direction from the start point at the absolute coordinate location -2,1. Pressing ENTER at the next To Point prompt ends the command.

Command: line

From point: -2,1

To point: @5,0

I.9 Basic Commands

I.9.1 Line

You can specify the endpoints of lines using two-dimensional (2D) or three-dimensional (3D) coordinates.

AutoCAD draws a line segment and continues to prompt for points. You can draw a continuing series of line segments, but each line segment is a separate object. Press ENTER to end the command.

For example, the following command sequence draws a single line segment.

Command:  line

Specify first point:  Specify a point (1)

Specify next point or [Undo]:  Specify a point (2)

     

Specify next point or [Undo]:  Press ENTER

Command options :

Continue

Continues a line from the endpoint of the most recently drawn line. If the most recently drawn line is an arc, its endpoint defines the starting point of the line, and the line is drawn tangent to the arc.

Close

Ends the last line segment at the beginning of the first line segment, which forms a closed loop of line segments. You can use Close after you have drawn a series of two or more segments.

Undo

Erases the most recent segment of a line sequence. Entering u more than once backtracks through line segments in the order you created them

  

I.9.2 Undo & Redo

Undo 

Reverses your last action. To reverse more than one action at a time, click the arrow next to the Undo button on the Standard toolbar and select the last in the sequence of actions you want to undo.

You can use the options of UNDO on the command line to undo more than one action at a time. Begin and End define a number of actions as a group, and Mark and Back work together to undo all actions back to a predetermined point.

When you use Back or Number to undo multiple actions, AutoCAD regenerates or redraws the drawing, if necessary. This occurs at the end of the UNDO command; therefore, entering undo 5 causes one regeneration, and u u u u u could cause as many as five.

UNDO has no effect on some commands and system variables, including those that open, close, or save a window or a drawing, display information, change the graphics display, regenerate the drawing, or export the drawing in a different format.

Redo 

REDO reverses the effects of a single UNDO or U command. REDO must immediately follow the U or UNDO command.

I.9.3 Erase 

AutoCAD removes the objects from the drawing

Command: erase

Select objects:  Use an object selection method and press ENTER when you finish selecting objects

I.9.4 Redraw

Refreshes the display in the current viewport

Command line:  redraw (or 'redraw for transparent use)

When BLIPMODE is on, marker blips left by editing commands are removed from the current viewport.

I.9.5 Regen

Regenerates the entire drawing from the current viewport

Command line:  regen

REGEN regenerates the entire drawing and recomputes the screen coordinates for all objects in the current viewport. It also reindexes the drawing database for optimum display and object selection performance.

I.10 Exiting AutoCAD 2005

To quit from AutoCAD 2005 we can use the following procedures :

File menu: Exit

Command line:  quit

Quits AutoCAD if there have been no changes since the drawing was last saved. If the drawing has been modified, AutoCAD prompts you to save or discard the changes before quitting.

You can quit a file that has been opened in read-only mode if you have made no modifications or if you are willing to discard them. To save modifications to a read-only drawing, use the SAVEAS command to save the drawing under another name.

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