Yamanta's AutoCAD Manual(2D Drafting)

An Introduction to

AutoCAD 2D Drafting

Prepared by:

Yamanta Raj Niroula Instructor

PENTASOFT Baneshwor Centre

An Introduction to AutoCAD

PENTASOFT

TABLE OF CONTENTS COMPUTERS AND CAD

6

AN INTRODUCTION TO AUTOCAD

7

HARDWARE COMPONENTS OF AUTOCAD: RECOMMENDED HARDWARE

7 9

THE FIRST LOOK AT AUTOCAD

10

INTRODUCTION TO THE GUI: COMMUNICATING WITH AUTOCAD FUNCTION KEYS

10 13 13

CO-ORDINATE SYSTEMS IN AUTOCAD THE X, Y CO-ORDINATE SYSTEM: CARTESIAN AND POLAR COORDINATES: ANGULAR MEASUREMENT ENTERING POINTS IN AUTOCAD: ICONS, KEYSTROKES AND MENUS DIRECT DISTANCE ENTRY INTRODUCTION HOW DOES IT WORK? A WORKED EXAMPLE

14 14 15 16 17 17 19 19 19 20

BASIC AUTOCAD TERMINOLOGY

22

INTRODUCTION TO DRAWING AND MODIFY COMMANDS

25

DRAWING OBJECTS

25

INTRODUCTION Lines Absolute Co-ordinate System (x, y) Relative Rectangular Co-ordinate System (@ x distance, y distance) Relative Polar Co-ordinate System (@ distance < angle) Construction Lines and Rays: Construction Lines Rays Polygon Donut Revcloud 3D Polyline Circles and Arcs Circle Arc Ellipse Create and Combine Areas (Region): Wipeout Boundary Points and Point Styles Multilines Multiline Style: SOLID OBJECTS EDITING INTRODUCTION

Prepared by: Yamanta Raj Niroula

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Erase Objects: OOPS Move Objects: Copy Objects: The COPY Command: Copybase Copyclip Copyhist Copylink: Rotate Objects Create an Array of Objects: The ARRAY command: Create Breaks Mirror Objects: The MIRROR Command Offset an Object: The OFFSET Command Scale Objects: The SCALE Command Trim or Extend Objects: The TRIM Command: The EXTEND Command Stretch Objects: The STRETCH Command Use Grips to Edit Objects Use Grip Modes Make Multiple Copies with Grips Control Grips in Blocks Lengthen Objects The LENGTHEN Command Create Fillets The FILLET Command: Create Chamfers The CHAMFER Command Disassociate Compound Objects (Explode) The EXPLODE Command The RENAME Command Copy Properties Between Objects The MATCHPROP Command Tips & Tricks

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CREATING AND WORKING WITH POLYLINES

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THE POLYLINE FAMILY The PLINE Command The RECTANGLE Command MODIFYING POLYLINES The PEDIT Command: SPLINE MODIFY SPLINES Introduction Edit Splines with Grips Refine the Shape of a Spline The SPLINEDIT Command: ZOOMING AND PANNING INTRODUCTION: The ZOOM Command Zoom Shortcut Menu PANNING A VIEW PAN AND ZOOM WITH THE AERIAL VIEW WINDOW The DSVIEWER Command UNITS & SCALES


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An Introduction to AutoCAD INTRODUCTION UNITS CONTROL The UNITS Command LINEAR UNITS ANGULAR UNITS UNIT PRECISION DRAWING LIMITS The LIMITS Command SELECTING OBJECTS IN AUTOCAD THE SELECT COMMAND OBJECT CYCLING: CREATING QUICK SELECTION SETS The QSELECT Command SELECTION SET FILTERS The FILTER Command CREATING NAMED SELECTION SET OF OBJECTS (GROUP) The GROUP Command WORKING WITH LAYERS AND LINETYPES LAYERS: The LAYER Command Layer Properties Manager Layer Property Types: Layer Display States Changing Layer Display Properties: Named Layer Filters WORKING WITH LINETYPES: Loading Linetypes: Setting Current Linetype: Changing the Linetype of an Object: Controlling Linetype Scale: Displaying Linetypes on Short Segments and Polylines THE LINETYPE COMMAND Linetype Manager OBJECT PROPERTIES DISPLAY AND CHANGE THE PROPERTIES OF OBJECTS The PROPERTIES Command ANNOTATING THE DRAWING INTRODUCTION CREATING TEXT AND LEADERS Creating Single Line Text The TEXT Command Creating Multiline Text Justifying Multiline Text Creating Stacked Characters Within Multiline Text The MTEXT Command WORKING WITH TEXT STYLES: The STYLE Command HATCHING AREAS AND EDITING HATCHES THE BHATCH COMMAND ADVANCED HATCH OPTIONS The Direct Hatch Option: EDITING A HATCH PATTERN: CREATING YOUR OWN HATCH PATTERN: THE SUPER HATCH COMMAND: DIMENSIONING


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DIMENSIONING BASICS PARTS OF A DIMENSION ASSOCIATIVE DIMENSIONS LINEAR DIMENSIONS The DIMLINEAR Command The DIMALIGNED Command BASELINE AND CONTINUED DIMENSIONS The DIMCONTINUE Command The DIMBASELINE Command CHANGING THE TEXT RADIAL DIMENSIONS The DIMDIAMETER Command The DIMRADIUS Command The DIMCENTER Command ANGULAR DIMENSIONS The DIMANGULAR Command ORDINATE DIMENSIONS The DIMORDINATE Command USING DIMENSION STYLES: The DIMSTYLE Command ADDING GEOMETRIC TOLERANCES Material Conditions Datum Reference Frames Projected Tolerance Zones Composite Tolerances ANNOTATION WITH LEADERS The Leader Command MODIFY EXISTING DIMENSIONS Apply a New Dimension Style to Existing Dimensions Override a Dimension Style Modify Dimension Text The DIMTEDIT Command Modify Dimension Geometry The DIMREASSOCIATE Command EXTRACTING OR CALCULATING GEOMETRIC INFORMATION FROM OBJECTS (INQUIRY COMMANDS) The ID Command The LIST Command OBTAINING DISTANCES, ANGLES, AND POINT LOCATIONS: The DIST Command OBTAINING AREA INFORMATION The AREA Command OTHER INQUIRY TOOLS: The TIME Command The STATUS Command The SETVAR Command OBJECT SNAP INTRODUCTION USING OBJECT SNAPS Snap to a Single Point Running Object Snaps Object Snap Restrictions GRID AND GRID SNAP Change Grid and Snap Spacing Change the Snap Angle and Base Point ORTHOGONAL LOCKING (ORTHO MODE) POLAR TRACKING AND POLARSNAP Polar Angles (Polar Tracking) Polar Distances (PolarSnap) COMBINE OR OFFSET POINTS AND COORDINATES


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An Introduction to AutoCAD Combine Coordinate Values (Coordinate Filters) OBJECT SNAPTRACKING SNAP TOOLS OBJECT SNAPS RUNNING OBJECT SNAPS OBJECT SNAP CYCLING USING TEMPORARY TRACKING POINTS OBJECT SNAP TRACKING POINT FILTERS AUTOCAD 2004 COMMAND ALIASES 3D A B C D E F G H I L M O P Q R S T U V W X Z


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Computers and CAD Computer Aided Design (CAD) can be defined as the use of computer systems to assist in the creation, modification, analysis or optimization of a design. The computer systems consist of the hardware and software to perform the specialized design functions required by the particular user firm. When we think of Computer Aided Design (CAD), certain questions arise that we never think of while working on the drawing board. We do not use the essential drawing board tools: paper, pencil, T-square, compass, eraser or scale, yet still have to design or make a drawing. When even one of these tools is missing we know how aggravating it can be. With CAD we don’t need even one of them! CAD is an electronic tool that enables you to make quick and accurate drawings with the use of a computer. Unlike the traditional methods of making drawings on a drawing board, with CAD you can sit back in an easy chair and create wonderful drawings just by clicking the buttons of a keyboard. Moreover, drawings created with CAD have a number of advantages over drawings created on a drawing board. CAD drawings are neat, clean and highly presentable. Electronic drawings can be modified quite easily and can be presented in a variety of formats. A decade ago, CAD was used only for specific engineering applications that required high precision. Due to CAD’s high price, only a few professionals could afford it. In recent years, however, computer prices have decreased significantly and more and more professionals are taking advantage of CAD. There are hundreds of CAD programs available in the CAD industry today. Some are intended for general drawing work while others are focused on specific engineering applications. There are programs that enable you to do 2D drawings, 3D drawings, renderings, shadings, engineering calculations, space planning, structural design, piping layouts, plant design, project management, etc. There is a CAD program for virtually every engineering discipline you can think of. CAD is primarily intended for single-line drafting. It has very limited capabilities to create artistic impressions. However, CAD’s 3D and rendering features are fascinating. You can create a 3D model of an object and view it from any angle. With proper shading and rendering, it can be made to look picture perfect! You can do amazing things with CAD that you never thought possible while creating drawings with a pen or pencil. The following are some of the important capabilities that make CAD a powerful tool: • • • • • • • • • •

Presentations Flexibility in editing Units & accuracy levels Storage and access for drawings Sharing CAD drawings Project reporting Engineering analysis Computer Aided Manufacturing (CAM) Design Add-on programs


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An Introduction to AutoCAD Welcome to the world of CAD - In this tutorial you will be learning the basics of AutoCAD – the most popular PC based 2D and 3D CAD system from the Autodesk Inc. Autodesk, the US based and fourth largest software firm in the world, is the publisher of AutoCAD. Apart from AutoCAD, Autodesk has a spectrum of products for various disciplines as follows • • • •

Mechanical - AutoCAD Mechanical, Autodesk Inventor Series. AEC - Architectural Desktop, Autodesk Civil Design, Autodesk VIZ, Autodesk Revit. GIS - Autodesk MAP, Autodesk Land Desktop, Autodesk Map Guide R to V - Autodesk Raster Design.

Hardware Components of AutoCAD: The following are the main hardware components of AutoCAD: • • • • • • • • •

System unit Central processing unit Memory Hard disk, floppy disk, CD-ROM External storage devices Monitor Printers and plotters Keyboard Digitizer, puck and mouse

• System Unit: The system unit is the computer that is used for all data processing. The main components of the system units are the central processing unit (CPU) and memory. In mainframe and minicomputers CPU and memory are usually separate compartments that house thousands of devices. In today' s PCs, however, they all fit in a small box commonly known as a desktop computer. Most desktop computers today come equipped with a hard disk, floppy disk drive and CD ROM. Let' s have a look at the components of a system unit: • • •

Central Processing Unit(CPU) Memory Hard disk, floppy disk, CD-ROM

• External Storage Devices: There are a number of external storage devices available such as magnetic tapes, zip drives and removable hard disks. They are commonly used to keep backup copies of


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electronic files for safekeeping. Magnetic tapes are quite common for storing large volumes of data. A magnetic tape that looks like a small videocassette can store thousands of megabytes of data. However, they are quite slow and require a lot of time to store or retrieve data. Zip drives were introduced recently; they use zip disks to store data. A zip disk is like an upgraded version of floppy disk that can store about 100MB of data. They are particularly helpful if you plan to use AutoCAD or other graphic programs that generate quite big data files. You can store an entire project on one zip disk that could take 50 or more floppy disks. Another new option for data storage is the removable hard disk. You can remove the entire hard disk from your computer and use it on another computer. This approach is commonly used when you need to work on different computers and you want the same information to be available instantly.

• The Monitor: The monitor is the computer screen and is used to display information. A good monitor is very important for AutoCAD in order to display fine graphics. A color monitor is essential because many AutoCAD drawing techniques are based on colors. Monitors are available in various sizes ranging from 13" to 30" or more. Today, average monitors have the ability to display millions of colors. The main factor that determines the quality of a monitor is the resolution. The term resolution refers to sharpness of an image displayed on the screen. Resolution is measured by the number of picture elements (pixels) that a screen can display. The more pixels and the closer they are, the sharper the image. The distance between pixels is called the "dot-pitch". The smaller the dot-pitch, the sharper the image. A 26 or smaller dotpitch monitor is recommended for AutoCAD applications.

• Printers and Plotters AutoCAD drawings are printed using fine-quality printers and plotters. Drawings are neat and clean and as accurate as the naked eye can see. You can print drawings at as much as 1200-dpi (dots per inch) accuracy. This means 1200 dots are printed in a oneinch-long line! All the text dimensions and other graphics are printed highly accurate, neat and crisp. You can print drawings with a lot of variations; for example, drawings can be printed with different sizes, line types, text fonts and colors. There are a variety of printers and plotters available in the computer industry. They work on different principles and their prices vary significantly. There are many types of pen plotters, ink-jet printers, laser printers and plotters, electrostatic printers, etc.

• Digitizer, Puck and Mouse The digitizer (also known as a graphic tablet) and the puck are the data input devices most commonly used in CAD systems. These devices allow you to enter point locations on the screen and to make selections from the menus. As the puck is moved over the surface of the digitizer, it moves the indicator (cursor) on the screen relatively. To enter a point, you need to position the cursor at the appropriate position on the screen and then press the "Enter" button on the puck. Digitizers are available in many sizes and


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styles. A number of commands are printed on the digitizer surface. To enter a command, place the puck over the desired command and press the "Enter" button. The selected command is instantly entered. The puck buttons are configured to perform many other tasks. For example, one button is used to make selections, another to enter the data, another to return to the previous menu and another to cancel the last command. A mouse is another pointing device that can be used with CAD. Like the puck, the mouse allows you to control the position of the cursor on the screen by rolling it across a flat surface, but it does not require a digitizer. Some programs support working with a mouse only, while others support both the mouse and the digitizer. A mouse is much cheaper than a digitizer or puck, but provides only limited data entry options.

Recommended Hardware Listed below are the hardware requirements for running AutoCAD 2004 on any system. • • • • • • • • • • • • • •

Pentium III (500 MHZ) or later 128 MB RAM 1024 x 768 VGA with True Color Installation 300 MB hard-disk space Pointing device (mouse or digitizer with Wintab driver) CD-ROM Drive -any speed (for installation only) Windows XP Professional, Windows 2000,Windows NT 4.0 with SP 6a or later Microsoft Internet Explorer 6.0 IBM-compatible parallel port Serial port (for digitizer and some plotters) Printer or plotter Modem (connection to Internet) Sound card for multimedia learning TCP/IP or IPX support (required only for multi-user, or floating license configuration)


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The First Look at AutoCAD Launching AutoCAD is easy. Just double-click the desktop or start the application by clicking, Start Programs Autodesk

shortcut on the

AutoCAD 2004 AutoCAD 2004.

After a few moments, you could see the AutoCAD interface as shown in the following figure. Take a look at it and familiarize with the various components of the Graphical User Interface (GUI) of AutoCAD.

Introduction to the GUI: The AutoCAD program window is divided into following parts: • • • • • • •

Title Bar Pull-down Menu bar Toolbars Drawing Area Scroll Bar Command Window Status Bar

• Title Bar: is.

This will show you what program you are running and what the current filename

• Pull-down menu Bar: Menus are available from the menu bar at the top of the AutoCAD drawing area. These are the standard pull-down menus through which you can access almost all commands. You can choose menu options in the following ways: 1. Click the menu name to display a list of options. Click the option to choose it, or press DOWN ARROW to move down the list and then press ENTER. 2. Press ALT and then enter the underlined letter in the menu name. For example, to open a new drawing, press ALT and press F to open the File menu. Then press ENTER to choose the highlighted option New.


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The default menu file is acad.mnu. You can specify a different menu (for example, a menu you have customized) in the Options dialog box, Files tab.

• Toolbars: There are many toolbars available in AutoCAD. Go to View > Toolbars from the drop down menu to see them all. For now make sure that the following toolbars are checked: Draw Modify -

Contains AutoCAD’s most common drawing tools Contains all of the common editing commands such as erase, copy etc. Object Properties - Contains ' layer'information as well as object colors and linestyle options. . Standard Toolbar - Contains open & save options as well as zoom & pan options. Object Snap AutoCAD' s intelligent drawing aid - joins lines at specific points. The toolbar has most of the standard Windows icons, as well as the most common AutoCAD commands. Toolbars contain buttons that start commands. When you move the pointing device over a toolbar button, the tooltip displays the name of the button. Buttons with a small black triangle in the lower-right corner have flyouts that contain related commands. With the cursor over the icon, hold down the pick button until the flyout appears. The Standard toolbar at the top of the drawing area is displayed by default. This toolbar is similar to those found in Microsoft Office programs. It contains frequently used AutoCAD commands such as DIST, PAN, and ZOOM, as well as Microsoft Office standard commands such as New, Open, and Save. AutoCAD initially displays several toolbars: • • • • • •

Standard toolbar Styles toolbar Layers toolbar Properties toolbar Draw toolbar Modify toolbar

You can display or hide these toolbars, and you can create your own toolbars. Toolbars can be moved from their default locations to any location on the screen. When they are in their default location, they are in their docked position. When they are in their default location where they are free floating, they are floating. A floating toolbar is located anywhere in the drawing area of the AutoCAD window, and you can drag it to a new location, resize it, or dock it. A docked toolbar is attached to any edge of the drawing area. While a toolbar is docked, it cannot be resized. You can move a docked toolbar by dragging it to a new docking location.


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• The Drawing Area: The drawing area is the workspace that occupies most part of the AutoCAD window. Everything that we draw appears in the drawing area. This is where you draw. You have an almost infinite area to draw and this is just a ' section'of the entire space.

• Scrollbars: These work like in other windows programs. You can also use the PAN command to move around your drawing.

• Status Bar: This allows to see and change different modes of drawing such as ORTHO, OSNAP, GRID, OTRACK etc.

A typical arrangement of elements in AutoCAD 2004 window

• Command Window: The command window appears at the bottom of the AutoCAD screen (as shown above) and displays the commands entered. Commands can be entered into the command line in text format, or by using the icons or drop down menus. ' Old School'CAD users tend to type each command into the command line, as was required with older versions of


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AutoCAD. It is much quicker to familiarize yourself with the tool bars and drop down menus. When you type a command, you will see it in command window. AutoCAD uses this space to ' prompt'you for information. It will give you a lot of information and tell you where you are in the command.

Communicating with AutoCAD AutoCAD is a perfect servant: it does everything you tell it to and no more. You can communicate with AutoCAD using the pull-down menus, screen menus, command line and the buttons on the toolbars. A command is a single-word instruction from the user to perform the required task. When you invoke a command, AutoCAD responds by presenting messages in the command prompt area, or by displaying a dialog box. The messages in the command prompt area often tell you, what to do next, or they offer a lot of options. A dialog box is like a form, you fill out on the computer screen. It lets you to adjust settings or make selections from a set of options pertaining to a command.

Function Keys AutoCAD provides a set of function keys for quick access to certain commands. Listed below are the function keys defined for AutoCAD. You might be referring to this list of function keys very often. Function Key

Function Defined in AutoCAD

F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11

Online Help Toggles between Command Window On and Off Toggles between OSNAP On and Off Toggles between Tablet On and Off Switches among Isoplanes Top, Right and Left Toggles between Coordinates On and Off Toggles between Grid On and Off Toggles between Ortho Mode On and Off Toggles between Snap Mode On and Off Toggles between Polar Tracking On and Off Toggles between Objects Snap Tracking On and Off


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Co-ordinate Systems in AutoCAD This lesson will explain coordinate systems which are crucial to understanding AutoCAD® and how to create drawings and objects. Below you will see a coordinate system with several points labeled. Notice the two thick lines on the coordinate system. The thick horizontal line is called the x-axis. The thick vertical line is called the y-axis. The intersection of these two lines is a point called the origin. The origin is the beginning reference point of the coordinate system. Any other point on the coordinate system is relative to the origin. The thin lines mark evenly spaced distances from the origin. The actual distance does not usually matter, as long as it is evenly spaced because a coordinate system is just a representation of something else. In AutoCAD®, a coordinate system is usually a representation of space. Another example of a coordinate system could be time. You may want to draw a rectangle that is 2 units long and 1 unit high. You could start at the origin and move to the right 2 units, and then up 1 unit. This would be a rectangle of the proportion that you wanted. The lower left corner of this rectangle would be the origin. The upper right corner of this rectangle would be 2 units on the x-axis, and 1 unit on the y-axis. You would refer to these as the x-coordinate or just x, and the ycoordinate or just the y. You would write these in a comma notation, first the x, then the y and sometimes you would put them in parentheses. So the coordinates for the upper right corner of our box would be (2,1). The coordinates for the lower left corner of our box would be (0,0), which are the coordinates of the origin. You should note that these coordinates are marks of points, not spaces or blocks, just a point of an intersection of a specified x and a specified y. You may specify points to the left of the x-axis or below the y-axis by specifying negative points. You can see some negative points labeled at -2,-1 and at -3,2 and at 1,-3. Coordinates do not have to be whole numbers. They may be fractions or decimals. In AutoCAD®, a grid is not used, but you are shown a rather open space known as the drawing area. A symbol called the UCS labels the origin and has arrows to specify the xaxis and the y-axis. Below, you will see a screenshot of AutoCAD® with lines drawn on top of the UCS symbol to further emphasize the x-axis and the y-axis which usually remain invisible.

The X, Y co-ordinate system: All drawings are superimposed on an invisible grid, or co-ordinate system, with a horizontal X-axis and a vertical Y-axis. You can establish grid and snap settings that match the units of the co-ordinate system or some multiple or fraction of it.


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As you draw, you can enter co-ordinates to locate a point. For example, you can draw a line by starting it at the 2,2 location in the co-ordinate system and end it at the 8,2 location, as shown in the above figure. This is called the Absolute Co-ordinate System. The X value of a Cartesian coordinate specifies the horizontal distance, and the Y value specifies the vertical distance. The origin point (0,0) indicates where the two axes intersect. Absolute co-ordinate values are based on the origin (0,0). Relative co-ordinate values are based on the very last point entered. They are useful for finding a series of points that are at a known distance apart. Various methods of entering 2D coordinates in AutoCAD are discussed below. Everything that you draw in AutoCAD is exact. It will be more accurate than you will ever need it to be. All objects drawn on the screen are placed there based on a simple X,Y co-ordinate system. In AutoCAD this is known as the World Co-ordinate System (WCS). You must understand this to know how to put things where you want them. (3-D work has an added axis, the Z-axis) 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 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).


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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. In AutoCAD, 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 this style in the Units Control dialog box. In order to work effectively with AutoCAD, you have to work with this system. Until you are comfortable and familiar with it, learning AutoCAD will be more of a chore. My experience in teaching is that the better a student is with co-ordinates, the better CAD draftsperson they are.

How it works: AutoCAD uses points to determine where an object is located. There is an origin where it begins counting from. This point is (0,0). Every object is located in relation to the origin. If you were to draw a line straight out to the right from the origin, this would be considered the positive X-axis. If you were to draw a line straight up, this would be the positive Y-axis. The point located at (9,6). This means that the point is 9 units over in the X-axis and 6 units up in the Y-axis. When you are working with points, X always comes first. The other point shown is (-10,-5). This means that the point is 10 units in the negative X-axis (left) and 5 units in the negative Y-axis (down). A line has two points, a start point and an end point. AutoCAD works with the points to display the line on the screen. Move your cursor over the picture above and you will see line drawn from the absolute points of (-10,-5) to (9,6). Most of the time you will not have an indication of where the origin is. You may need to draw a line from the endpoint of an existing line. To do this you use relative points. These work the same way, but you have to add the @ symbol (shift+2) to tell AutoCAD that this next point is relative from the last point entered. It’s a simple system, but mastering it is the key to working with AutoCAD and is explained below.

Angular Measurement AutoCAD measures angles in a particular way also. Look at the diagram below and then place your mouse on it to see how this is done.


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When drawing lines at an angle, you have to begin measuring the angle from 0 degrees, which is at the 3 o' clock position. If you drew a line at 90 degrees, it would go straight up. The example above (when you move your mouse over it) shows a line drawn at +300 degrees, or -60 degrees. You might not always have an obvious reference point for 0 degrees.

Entering Points in AutoCAD: You can enter points directly on the command line using three different systems. The one you use will depend on which is more applicable for the situation. The first assignment will get you used to this. The three systems are as follows: ABSOLUTE CO-ORDINATES - Using this method, you enter the points as they relate to the origin of the WCS. To enter a point, just enter in the exact point as X, Y. RELATIVE CO-ORDINATES - This allows you to enter points in relation to the first point you have entered. After you' ve entered one point, the next would be entered as @X, Y. This means that AutoCAD will draw a line from the first point to another point X units over and Y units up relative to the previous point. POLAR CO-ORDINATES - You would use this system if you know that you want to draw a line a certain distance at a particular angle. You would enter this as @D
Icons, Keystrokes and Menus There are many ways to do things in most windows programs. AutoCAD is no exception. Everyone will develop a way that works best for him or her. In this course, we will primarily be working with the keystroke commands. The reason for this is because they will work in most AutoCAD versions (including DOS versions), and in some other CAD programs. The icons work well, but as you will see, icons can be placed anywhere on the screen and can be difficult to find quickly. The pull-down menus will access almost all commands, but are a slower way of doing things.

Example: If you want to draw a line, you can do it a few ways:


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An Introduction to AutoCAD • • •

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At the command line type: LINE (or) L and press the ENTER key. Select the line icon from the DRAW toolbar. Select Draw Line from the pull-down menu.

All three approaches will do the same thing: prepare AutoCAD to draw a line where you tell it. AutoCAD is a popular program because it can be customized to suit an individual' s needs. The toolbars are a good example of this. You can have the toolbars you use most often on the screen all the time. You can easily make them go away so that you have more drawing space. You can also customize them so you have the most common commands on one toolbar. For example, the dimensioning toolbar is one that you will not want taking up space on your screen while drawing, but is very handy when you' re dimensioning your drawing.


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Direct Distance Entry Introduction To specify a line length quickly, without entering coordinate values, you can specify a point by moving the cursor to indicate a direction and then entering the distance from the first point. You can use direct distance entry to specify points for all commands requiring more than one point. When ORTHO mode or polar tracking is on, this method is an efficient way to draw lines of specified length and direction. Direct distance entry is one of those AutoCAD features that is often overlooked. This is rather unfortunate because it can be extremely useful and an amazing time-saver. Basically, direct distance entry enables you to draw an object, such as a line, by pointing in a particular direction with the cursor and entering a distance at the command line.

How does it work? Say, for example, you wanted to draw a horizontal line with a length of 30 drawing units. Start the Line command, Draw Line from the pull-down menu or from the Draw toolbar. When prompted, to specify the first point for the line, pick a point somewhere on the left side of the drawing area. You now need to constrain the line to the horizontal. You can do this using Polar Tracking. Use the POLAR button on the status bar to turn on Polar Tracking. Usually, Polar Tracking is on by default, so you may not need to do this. Now, move your cursor to the right of the first pick point. If you are within a few degrees of the horizontal, you should see something similar to the illustration on the right. Hold your cursor in this position and simply enter 30 at the keyboard. When you hit the Return key, a line segment is drawn, 30 units long and in the direction you were pointing. Obviously, you could vary this sequence to get different effects. If you only want to draw horizontal or vertical lines, you could use Ortho rather than Polar Tracking. Or, you could configure polar tracking to snap to other angles like 45º or 30º. You might even want to turn both Ortho and Polar Tracking off and use free angles. It' s also worth pointing out that when Polar Tracking has snapped to an angle, as in the illustration above, a Tool Tip is displayed. This Tool Tip displays a relative polar co-ordinate from the first pick point to the current cursor position. The first number is the distance between the two points and it can be quite useful as a drawing guide since the value updates dynamically. below.

To get a clearer idea how direct distance entry works, follow the worked example


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A Worked Example In this exercise, we will use direct distance entry to draw the closed shape shown below using the associated dimensions. •

Check that you have either Polar Tracking or Ortho mode turned on.

•

Start the Polyline command, Draw the Draw toolbar.

•

When prompted to specify the first point, pick a point somewhere in the lower left quadrant of the drawing area. This will be the point marked "start" in the illustration.

Polyline from the pull-down menu or from

Now, follow the command sequence below. In each case, point the cursor in the direction you want the line drawn and enter the distance for that particular line segment at the keyboard. Point up Specify next point or [Arc/Halfwidth/Length/Undo/Width]: 40 Point right Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: 15 Point down Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: 25 Point right Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: 20 Point up Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: 25 Point right Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: 15 Point down Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: 40 You should now be at the point marked "end" on the illustration. All you need to do now is enter "C" to close the polyline and end the command. Specify next point or [Arc/Close/Halfwidth/Length/Undo/Width]: C

The closed polyline shape you have drawn is located arbitrarily because you just picked a start point somewhere in the drawing area. If you had wanted to start at a particular location, you could have entered a co-ordinate value for the start point instead of just picking.


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Obviously, the exercise above is a very simple example but there are many circumstances where direct distance entry can be used. It' s a very useful tool to add to your AutoCAD skills toolbox and can help you towards greater drawing efficiency.


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Basic AutoCAD Terminology Here are some basic terms that you will need to know to begin using AutoCAD. Absolute co-ordinates

A way of inputting points based on AutoCAD' s origin.

Acad.dwt

This is the default template that automatically loads whenever you start a drawing session. It can be customized.

Associated Dimensioning

Dimensions that are associated with specific points will update as that point is moved.

Backup file

AutoCAD can be set to automatically backup your drawing and save it. This is a safeguard in case your file gets corrupted. It is saved with a .BAK extension

Block

A pre-drawn image you can insert in your drawing to save time and make your file size smaller.

Crosshairs

This is your cursor when it is in the drawing space.

Cursor

Your cursor will change depending on where it is in the program.

Database

An AutoCAD drawing file is actually one large database containing all the information needed to reproduce the objects when the file is opened. Info for layers and linetypes, etc are stored in this manner.

Dialog box

AutoCAD uses a large number of dialog boxes to get information from you. You must know how input the information that it asks for.

Drawing template file

This is a file that contains preset values for frequently used settings. AKA a prototype drawing. The file extension is DWT.

Extents

The outer boundaries of the objects you have drawn.


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Grid

This is pattern of dots displayed on the screen to guide you. It can be toggled on and off by pressing the F7 key.

Grips

Small ' handles'on objects that allow for quick editing.

Layer

All objects are drawn on a layer. You can group objects (such as electrical) on a single layer and organize your drawing.

Layout Tabs

An optional area used for plotting your drawings.

Limits

A setting to impose an ' artificial'boundary on your drawing and scale your text and dimensions, etc.

Linetype

All objects are drawn with a particular linetype. Examples would be solid, center, dashed, etc.

Model space

The drawing space where you ' model'the objects.

Modify

A generic term used for changing your objects

Object

Any item that is in the AutoCAD database. Also known as an entity.

Origin

The (0, 0) point of your current co-ordinate system.

Ortho mode

This is a drawing mode that allows you to draw only perpendicular lines. It is toggled on and off by pressing the F8 key.

Osnap - Object Snap

This is a method of ' snapping'to certain, precise points on an object.

Path

The specific folder where AutoCAD looks for, or saves files.

Pick

To select an object by ' left-clicking'on it.

Plot

Also known as print. To make a hard copy of your drawing.

Polar co-ordinates

A way of inputting points based on distance and angle.


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Property

Any specific characteristic of an object such as layer, scale, linetype, start point, etc.

Relative co-ordinates

A way of inputting points based on a starting point.

Selection set

The current group of objects selected for modifying.

Snap

This is a drawing mode that allows you to snap your cursor to precise points laid out in a grid pattern. Toggle with the F9 key.

Styles

Formatting that defines the look of text, dimensions, etc.

Units

The basic drawing unit set for you drawing. For example, you can use inches or millimeters depending on your needs. You can also set the precision you want displayed, such nearest 1/4", 1/2" 1/64", etc.

User co-ordinate system (UCS)

Modifications made to the World Coordinate System (WCS) results in a User Coordinate System (UCS)

View

A particular area of your drawing.

Viewport

A separate ' window'on your drawing. You may have more than one viewport visible to see different areas of your drawing at the same time.

Wizard

An easy step-by-step instruction set to help you set-up certain aspects of your drawing.

World Co-ordinate System (WCS)

This is the common X-Y co-ordinate system that is the default. If it is modified, it becomes a User co-ordinate System (UCS)

Zoom

To view either a smaller section of your drawing (zoom in) or a larger section (zoom out)


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Introduction to Drawing and Modify Commands AutoCAD allows you to have access to a large number of commands. The general rule is that you will use 20% of the commands 80% of the time. We will start by introducing you to the most common drawing commands. When you combine these with the basic modify commands, you will be able to make elaborate drawings quite quickly. The important thing to remember is that AutoCAD will expect you give it information in a very particular order. The most frustrating thing when you begin using this program is that you will try to do something, but AutoCAD will ' not work' . In most cases, it means that you are trying to input information at the wrong time. This is why it is very important to be in the habit of looking at the command line. The command line tells you what information AutoCAD requires to continue. Your first drawing assignment will be to use the drawing commands in conjunction with the co-ordinate system defined above. This is a basic assignment, but it is very important to understand how to give the program accurate information. You will use the following commands:

Drawing Objects Introduction The Draw commands can be used to create new objects such as lines and circles. Most AutoCAD drawings are composed purely and simply from these basic components. A good understanding of the Draw commands is fundamental to the efficient use of AutoCAD. The sections below cover the most frequently used Draw commands such as Line, Polyline and Circle as well as the more advanced commands like Multiline and Multiline Style. As a newcomer to AutoCAD, you may wish to skip the more advanced commands in order to properly master the basics. You can always return to this tutorial in the future when you are more confident. In common with most AutoCAD commands, the Draw commands can be started in a number of ways. Command names or short-cuts can be entered at the keyboard; commands can be started from the Draw pull-down menu, shown on the right or from the Draw toolbar. The method you use is dependent upon the type of work you are doing and how experienced a user you are. Don' t worry too much about this; just use whatever method feels easiest or most convenient at the time. Your drawing technique will improve over time and with experience so don' t expect to be working very quickly at first. If you are working with the pull-down menus, it is worth considering the visual syntax that is common to all pull-downs used in the Windows operating system. For example, a small arrow like so "" next to a menu item means that the item leads to a submenu that may contain other commands or command options. An ellipsis, "…" after a Prepared by: Yamanta Raj Niroula

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menu item means that the item displays a dialogue box. These little visual clues will help you to work more effectively with menus because they tell you what to expect and help to avoid surprises for the newcomer.

Lines Lines are probably the most simple of AutoCAD objects. Using the Line command, a line can be drawn between any two points picked within the drawing area. Lines are usually the first objects you will want to draw when starting a new drawing because they can be used as "construction lines" upon which the rest of your drawing will be based. Never forget that creating drawings with AutoCAD is not so dissimilar from creating drawings on a drawing board. Many of the basic drawing methods are the same. Anyone familiar with mathematics will know that lines drawn between points are often called vectors. This terminology is used to describe the type of drawings that AutoCAD creates. AutoCAD drawings are generically referred to as "vector drawings". Vector drawings are extremely useful where precision is the most important criterion because they retain their accuracy irrespective of scale. With the Line command you can draw a simple line from one point to another. When you pick the first point and move the cross-hairs to the location of the second point you will see a rubber band line which shows you where the line will be drawn when the second point is picked. Line objects have two ends (the first point and the last point). You can continue picking points and AutoCAD will draw a straight line between each picked point and the previous point. Each line segment drawn is a separate object and can be moved or erased as required. To end this command, just hit the Enter key on the keyboard. Command: LINE Specify first point: (pick P1) Specify next point or [Undo]: (pick P2) Specify next point or [Undo]: Enter (to end)

You can also draw lines by entering the co-ordinates of their end points at the command prompt rather than picking their position from the screen. This enables you to draw lines that are off screen, should you want to.

Absolute Co-ordinate System (x, y) To enter an absolute coordinate, specify a point by entering its X and Y values in the format X, Y. Use absolute coordinates when you know the precise X and Y values of the point from the origin. The following sequence of coordinates draw a triangle, as shown below. Command: _line Specify first point: 3, 3 Specify next point or [Undo]: 7, 3 Specify next point or [Undo]: 5, 5 Specify next point or [Close/Undo]: c


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Relative Rectangular Co-ordinate System (@ x distance, y distance) Use relative coordinates when you know the position of a point with respect to the previous point. The relative rectangular coordinate is represented in the following format: @ x-displacement, y-displacement. Command: _line Specify first point: Specify next point or [Undo]: @4, 0 Specify next point or [Undo]: @0, 4 Specify next point or [Close/Undo]: Specify next point or [Close/Undo]: Specify next point or [Close/Undo]: Specify next point or [Close/Undo]:

2, 2 @-2, 0 @0,-2 @-2, 0 c

Mostly, an absolute co-ordinate is given at the Specify first point: Distance is measured +ve towards right and up and it is measured –ve towards left and down.

Relative Polar Co-ordinate System (@ distance < angle) Polar co-ordinate system uses a distance and an angle with reference to the previous point to locate a point. Angles are measured in anti-clock direction, taking 0° towards right. The relative polar coordinate is represented in the following format: @ distance < angle. Command: _line Specify first point: 2, 3 Specify next point or [Undo]: @4<0 Specify next point or [Undo]: @4<90 Specify next point or [Close/Undo]: @4<180 Specify next point or [Close/Undo]: c

Construction Lines and Rays: Lines that extend to infinity in one or both directions, known as rays and construction lines, respectively, can be used as references for creating other objects. For example, you can use construction lines to find the center of a triangle, prepare multiple views of the same item, or create temporary intersections to use for object snaps. Infinite lines do not change the total area of the drawing. Therefore, their infinite dimensions have no effect on zooming or viewpoints, and they are ignored by commands that display the drawing extents. You can move, rotate, and copy infinite lines just as you can move, rotate, and copy other objects. You may want to create infinite lines on a construction line layer that can be frozen or turned off before plotting.

Construction Lines A construction line (xline) can be placed anywhere in three-dimensional space. You can specify its orientation in several ways. The default method for creating the line is the two-point method: you specify two points to define the orientation. The first point, the Prepared by: Yamanta Raj Niroula

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root, is the conceptual midpoint of the construction line, that is, the point snapped to by the Midpoint object snap. You can also create construction lines in several other ways. (a) Horizontal and Vertical. Create construction lines that pass through a point you specify and are parallel to the X or Y axis of the current UCS. (b) Angle. Creates a construction line in one of two ways. Either you select a reference line and then specify the angle of the construction line from that line, or you create a construction line at a specific angle to the horizontal axis by specifying an angle and then a point through which the construction line should pass. (c) Bisector. Creates a construction line that bisects an angle you specify. You specify the vertex and the lines that create the angle. (d) Offset. Creates a construction line parallel to a baseline you specify. You specify the offset distance, select the baseline, and then indicate on which side of the baseline to locate the construction line. The Construction Line command creates a line of infinite length which passes through two picked points. Construction lines are very useful for creating construction frameworks or grids within which to design. Construction lines are not normally used as objects in finished drawings, it is usual, therefore, to draw all your construction lines on a separate layer which will be turned off or frozen prior to printing. See the Object Properties tutorial to find out how to create new layers. Because of their nature, the Zoom Extents command option ignores construction lines. XLINE is a linear object, which starts at infinite and ends at infinite, or we can say that it is a line, which has no start or end points but passes through a specified point. These lines are used for projections. Command: XLINE Specify a point or [Hor/Ver/Ang/Bisect/Offset]: Use one of the point fixing methods Specify through point: Use one of the point fixing methods Specify through point: Use one of the point fixing methods

You may notice that there are a number of options with this command. For example, the "Hor" and "Ver" options can be used to draw construction lines that are truly horizontal or vertical. In both these cases, only a single pick point is required because the direction of the line is predetermined. To use a command option, simply enter the capitalized part of the option name at the command prompt. Follow the command sequence below to see how you would draw a construction line using the Horizontal option. Point Specifies the location of the infinite line using two points through which it passes. Specify through point: Specify the point (2) through which you want the xline to pass, or press ENTER to end the command


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AutoCAD creates the xline through the specified point. Hor point.

Creates a horizontal xline passing through a specified

Specify through point: Specify the point (1) through which you want the xline to pass, or press ENTER to end the command

AutoCAD creates the xline parallel to the X axis.

Ver Creates a vertical xline passing through a specified point. Specify through point: Specify the point (1) through which you want the xline to pass, or press ENTER to end the command

AutoCAD creates the xline parallel to the Y axis. Ang Creates an xline at a specified angle. Enter angle of xline (0) or [Reference]: Specify angle or enter r

an

Angle of Xline Specifies the angle at which to place the line. Specify through point:

AutoCAD creates an xline through the specified point, using the specified angle. Reference Specifies the angle from a selected reference line. The angle is measured counterclockwise from the reference line. Select a line object: Select a line, polyline, ray, or xline Enter angle of xline <0>: Specify through point: Specify the point through which you want the xline to pass, or press ENTER to end the command


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AutoCAD creates an xline through the specified point, using the specified angle. Bisect Creates an xline that passes through the selected angle vertex and bisects the angle between the first and second line. Specify angle vertex point: Specify a point (1) Specify angle start point: Specify a point (2) Specify angle end point: Specify a point (3) or press ENTER to end the command

The xline lies in the plane determined by the three points. Offset Creates an xline parallel to another object. Specify offset distance or [Through] : Specify an offset distance, enter t, or press ENTER

Offset Distance Specifies the distance the xline is offset from the selected object. Select a line object: Select a line, polyline, ray, or xline, or press ENTER to end the command Specify side to offset: Specify a point and press ENTER to exit the command

Through Creates an xline offset from a line and passing through a specified point.

Select a line object: Select a line, polyline, ray, or xline, or press ENTER to end the command Specify through point: Specify the point through which you want the xline to pass and press ENTER to exit the command

Rays A ray is a line in three-dimensional space that starts at a point you specify and extends to infinity. Unlike construction lines, which extend in two directions, rays extend in only one direction. Using rays instead of construction lines can help reduce visual clutter. Like construction lines, rays are ignored by commands that display the drawing extents. RAY command creates semi-infinite lines commonly used as construction lines. A ray has a finite starting point and extends to infinity. Command: RAY Specify start point: Specify a point (1) Specify through point: Specify a point for the ray to pass through (2)


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AutoCAD draws a ray and continues to prompt for through points so you can create multiple rays. The ray is extended to the edge of the display in the direction defined by the starting point and the through point. Press ENTER to end the command.

Polygon A polygon is a polyline object. AutoCAD draws polylines with zero width and no tangent information. You can use the PEDIT command to change these values. The Polygon command can be used to draw any regular polygon from 3 sides up to 1024 sides. This command requires four inputs from the user, the number of sides, a pick point for the centre of the polygon, whether you want the polygon inscribed or circumscribed and then a pick point which determines both the radius of this imaginary circle and the orientation of the polygon. The polygon command creates a closed polyline in the shape of the required polygon. Creating polygons is a simple way to draw squares, equilateral triangles, octagons, and so on. The following illustrations show polygons drawn using the three methods. In the first two illustrations, point 1 is the center of the polygon and point 2 defines the radius length, which is being specified with the pointing device.


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There are many ways to create polygons: •

Specifying the radius when you know the distance between the center of the polygon and the endpoint of each side (inscribed)

•

Specifying the radius when you know the distance between the center of the polygon and the midpoint of each side (circumscribed)

•

Specifying the length of an edge and where you want to place it

Use RECTANG rather than POLYGON to create rectangles.

Draw Toolbar: Draw menu: Polygon Command: polygon Enter number of sides : Enter a value between 3 and 1024 or press ENTER Specify center of polygon or [Edge]: Specify a point (1) or enter e

Center of Polygon

Polygons

Defines the center of the polygon. Enter an option [Inscribed in circle/Circumscribed : Enter i or c or press ENTER


about

circle]

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Inscribed in Circle – Specifies the radius of a circle on which all vertices of the polygon lie. Specify radius of circle: Specify a point (2) or enter a value

Specifying the radius with your pointing device determines the rotation and size of the polygon. Specifying the radius with a value draws the bottom edge of the polygon at the current snap rotation angle. Circumscribed about Circle – Specifies the distance from the center of the polygon to the midpoints of the edges of the polygon. Specify radius of circle: Specify a distance

Inscribed in circle

Circumscribed about circle Specifying the radius with your pointing device determines the rotation and size of the polygon. Specifying the radius with a value draws the bottom edge of the polygon at the current snap rotation angle. Edge - Defines a polygon by specifying the endpoints of the first edge.

Specify first endpoint of edge: Specify a point (1) Specify second endpoint of edge: Specify a point (2)

Donut width.

Donuts are filled rings or solid-filled circles that actually are closed polylines with

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.


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A donut is constructed of a closed polyline composed of wide arc segments. How AutoCAD fills the interior of a donut depends on the current setting of the FILL command. This command draws a solid donut shape; actually it' s just a closed polyline consisting of two arc segments which have been given a width. AutoCAD asks you to define the inside diameter i.e. the diameter of the hole and then the outside diameter of the donut. The donut is then drawn in outline and you are asked to pick the centre point in order to position the donut. You can continue picking centre points to draw more donuts or you can hit Enter to end the command. Surprisingly, donuts are constructed from single closed polylines composed of two arc segments which have been given a width. Fortunately AutoCAD works all this out for you, so all you see is a donut. Command: donut Specify inside diameter of donut : Specify a ENTER If you specify an inside diameter of 0, the donut is a Specify outside diameter of donut : Specify a ENTER Specify center of donut or : Specify a point (1) end the command

distance or press filled circle. distance or press or press ENTER to

AutoCAD sets the location of the donut based on the center point. After you specify the diameters, AutoCAD prompts you for the locations at which to draw donuts. AutoCAD draws a donut at each point specified (2). As an alternative to picking two points or entering a value for the diameters, you could just hit Enter to accept the default value. Most AutoCAD commands that require user input have default values. They always appear in triangular brackets like this .


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Curiously enough AutoCAD doesn' t seem to mind if you make the inside diameter of a donut larger than the outside diameter, try it and see.

Revcloud Creates a polyline of sequential arcs to form a cloud shape

Draw toolbar: Draw menu: Revision Cloud Command: revcloud Minimum arc length: 0.5000 Maximum arc length: 0.5000 Specify start point or [Arc length/Object/Style]

Yamanta's AutoCAD Manual(2D Drafting)

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