AutoCAD Tutorial PDF

AutoCAD ======= **INTRODUCTION TO AutoCAD** AutoCAD is a general purpose Computer Aided Drafting application program designed for use on single use, desktop personal computers and graphic workstations. It was initially developed in early 1980's by AutoDesk Inc, Sausalito, California, USA. **DEFIN...

AutoCAD ======= **INTRODUCTION TO AutoCAD** AutoCAD is a general purpose Computer Aided Drafting application program designed for use on single use, desktop personal computers and graphic workstations. It was initially developed in early 1980's by AutoDesk Inc, Sausalito, California, USA. **DEFINITION** AutoCAD is an interactive drawing system designed to permit a user to construct or edit a drawing on a graphics display screen. To this extent, it is analogous to a word- processing program, except that in this case the thing is being processed is a drawing. **What's in an AutoCAD Drawing?** An AutoCAD drawing is made up of entities. These can be either simple graphic primitive such as; lines, circles, text, etc.; or blocks which are group of entities. The graphic primitives are defined geometrically in terms of the normal Cartesian coordinate system (right handed system with positive X- axis to the right, positive Y-axis up to the screen and positive Z-axis coming out of the screen towards the user. Hence, for example, lines are defined by their end point coordinates and radius. Each entity also has certain attributes associated with it, such as line style, text font or color. A **block** is a group of entities that can be manipulated as a single unit. Once created, a block maybe moved, scaled, rotated, copied or deleted. A block can be created by collecting together a group of entities from the current drawing (the drawing being currently edited) and assigning a single name to that group. Alternatively, and existing drawing (from disk) can be inserted into the current drawing as a block. Equally, a block from the current drawing can be written out to a file as a new drawing. **The AutoCAD Drawing Screen** **COMMAND WINDOW** **Is a dockable window in which you enter commands where AutoCAD displays prompts and messages. Generally the command line at the lowest line with two or three previous prompt lines called the command history is sufficient. Pressing the function key F2 will display the AutoCAD Text Screen which displays where you can view more of the command history lines.** **STATUS BAR** **Displays the cursor location's coordinate in the Drawing Window and the status of modes such as the Grid and Snap. Mode names are always visible in the status bar as selectable buttons. Double click Snap, Grid or Ortho to turn their respective modes on or off.** **SCROLL BARS** **Functions like any scrollbar in the window's environment- to help view more of the window in any direction indicated by the arrows.** **SCREEN MENU** **By default is invisible when AutoCAD is started Lower AutoCAD versions display this other means of viewing the AutoCAD command menu. To display, look in Tools Menu under Preferences option.** **HOW TO ACCESS COMMAND** You use AutoCAD by running commands using any of these methods: - Choosing a menu item from the Menu Bar - Clicking a Tool or Icon on the Toolbar - Choosing a menu item from the screen menu if it is displayed - Entering or typing the command at the command prompt in the command window The LINE Command 1\. Type L then press enter, or click at the line icon or select Line from the draw menu. 2\. Specify the starting point using the mouse to move across the drawing area and indicate its location by clicking the left button to fix the starting point. You may specify the starting point by typing its x, y, z coordinates 3\. Specify the end point of the first segment of the line ( if you intend to do the series of lines) 4\. Specify the next end point/s of the adjoining segments. 5\. Press enter to complete the line or series of line, or simply press the escape key. The **RECTANGLE** Command 1\. Type RECTANG then press enter of click the rectangles icon or select Rectangle from the Draw Menu. 2\. Specify the location of the corner of the rectangle or square using the mouse or by inputting it x, y, z coordinates. The **POLYGON** Command 1.Type POLYGON then press enter or click at the Polygon icon shown at the left, or select Polygon from the Drawing Menu. 2\. Enter the number of sides of the Polygon about to be drawn. 3\. Specify whether the Polygon is inscribed or circumscribe in the circle whose radius shall be specified in the next step. 4\. Specify the radius of the inscribed or circumscribe circle. **OBJECT SNAPS** **The OBJECT SNAPS TOOLBAR** The object snaps is the powerful precision tool that is used in any CAD program. This is the quick way of locating points on an existing object without having to know the coordinates or draw construction lines. The object snaps toolbar shown above can be displayed from the view menu under toolbars option. **Endpoint-** snaps to the closest endpoint of selected objects such as lines or arcs. **Midpoint-** snaps to the midpoint of selected objects such as in lines or arcs. **Intersection**- snaps to the intersection of selected lines, arcs, circles and splines. **Apparent intersection**- includes two separate snap modes: Apparent intersection and Extended apparent intersection. **Center-** snaps to the center of a selected arc, circle or ellipse **Quadrant-** snaps to the closest quadrant (0°, 90°, 180° and 270°) of an arc, circle or ellipse **Tangent-** snaps to the point on a circle, arc, or ellipse that when connected to the last point forms a line tangent to that object. **Perpendicular-** snaps to the point on an object that forms a perpendicular alignment with another object or with an imaginary extension of that object. **Node-** snaps to a point object drawn with the POINT command. **SETTING RUNNING OBJECT SNAPS** 1. From the tools menu choose Object snap settings. Or click Object snaps settings icon. 2\. In the Osnap settings dialog box select the running object snaps you want to use. 3\. To change the size of the aperture box, drag the slider bar under Aperture size. 4\. Choose OK. You can quickly turn Running Object Snaps on and off without having to re specify your object snap on the status bar. You can also switch Running Object snaps on and off pressing CTRL+ F or F3. Turning Osnaps on when running snaps are set displays the Osnaps Settings dialog box. **SAVING DRAWINGS** When you are working on a drawing, you should save it frequently to beat power interruption or computer failures during the drawing session. To save a drawing for the first time after some time into the drawing session, whether or not it is finished. 1\. **Type Save**, then press enter 2\. Check if this is the right folder to save in **CENTER RADIUS** 2. Specify the center point using the mouse or by inputting its coordinates. (default option) 3. Specify the radius either by typing the radius value or dragging the **CENTER, DIAMETER** 2. Specify the center point using th mouse or by inputting its coordinates. 3\. Specify the diameter either by typing or dragging the mouse as in the Center, radius option. **TWO POINTS** 2. Specify the first point which defines the diameter of the circle to be made 3\. Specify the other point defining the diameter of the circle. **THREE POINTS** 2. Specify any three points which the circle to be made passes through **TAN, TAN, RADIUS** 2.Specify the object that the circle to be made is tangent to approximating to the location of the point of tangency by clicking at the object using the mouse. 3.Specify the object that the circle is also tangent to approximating the point of tangency by clicking at the object using the mouse. 4\. Then specify the radius of the circle to be made (previous version read TTR) **TAN, TAN, TAN** This option is very much like Tan, tan, radius option except that you don't specify the radius of the circle to be made but just specify the objects that the circle to be made is tangent to by simply clicking at these objects using the mouse. This option does not have an icon The options enumerated above ar better appreciated when the exercise for making circles incorporating the snap modes are performed see Exercise in drawing Circles. To erase any objects 1. Type E then press Enter. Or Click the icon show on the left from the Modify Toolbar 2. Select the object or objects you wish to erase using any of the selection modes (which will be discuss soon) the selected objects will be highlighted as they are picked. 3. When selection is enough press enter after which the selected objects will disappear. You may select or click at the objects you wish to erase first using any selection mode available, then invoke the Erase Command using an option stated in step number 1, then they disappear. Like any windows application you can undo your most recent action or several actions. Use the U command to undo a single action(this is the simplest to uses its icon shown on the left is clicked rom the standard toolbar) and the Undo command to undo several actions. If the UNDO command is erroneously used or overshoots in cancelling previous commands, the REDO command restores any action undone by the UNDO command. **NOTE :** To select objects using single selection. 1. Invoke any Editing command, the command line prompts " Select Objects" crosshair turns into pick box. 2. Using the pick box, pick the object by pointing and clicking the mouse. The object becomes highlighted. 3. The " Select Objects" continues , pick some more objects using the same method to add to the set. 4. Press Enter key to accept the selection set. To select multiple objects using Rectangular Window. 1. Invoke any Editing command, the command line prompts " Select Objects" crosshair turns into pick box. 2. Specify the corner of the window by clicking anywhere in the drawing area without hitting an object. The command line prompts you to specify the "Other Corner" 3. Drag the mouse to the right, a solid selection window is created. Enclosed the objects you want to select. 4. Click for the other corner all items totally enclosed are highlighted. 5. Press Enter key to accept the selection set. **Note: When window selection is accidentally invoked press ESC key to abort.** To select multiple objects using Crossing Window 1. Follow steps 1-2 of the previous instructions 2. Drag the mouse to the left of the first corner, a broken selection window is creatd. 3. Click for the other corner, all items [totally enclosed and crossed] by the window are highlighted. 4. Press Enter key to accept the selection set. To remove objects from the current selection set. 1. Select multiple objects. 2. While command line prompts "Select Objects" type R for remove, press Enter. Command line changes from " Select Objects" to "Remove Objects" 3. Using single multiple selection, pick the objects you want to remove from the selection set. The object's highlight is removed. 4. Press enter key to accept the selection set. To add objects to the Selection Set while in Remove objects mode 1. In the "Remove Objects" prompt type A for add. Command prompt changes back to "Select Objects" 2. Add objects to any selection method. 3. Press Enter to accept selection. Other Selection Modes Selects objects within a polygon defined by points indicated around to the objects to be selected. It can be in any shape but cannot cross or touch itself. **CPolygon** **Fence** The **ZOOM** Command The AutoCAD draws object scaled 1:1. The size of the drawing that you see in the drawing window is relative to its magnification. A fully scaled skyscraper drawing may be seen in your drawing window as a dot only when viewed too far away. On the other hand, when viewed too closely, the drawing window may even appear empty. Reducing or increasing the apparent magnification of the graphics display is called zooming. Magnifying the image to view details more closely is called zooming in. Shrinking the image to see a larger portion of the drawing is zooming out. AutoCAD offers a number of ways in changing the magnification. All of those are under the ZOOM command. **To Zoom in RealTime Mode** 1. In the command line, type Z. Press Enter twice; or click the Zoom Realtime icon in the Standard Toolbar or Choose Zoom the Realtime from the View Menu. The cursor changes into Zoom Realtime Icon. 2. Hold down the left mouse button and drag the cursor up to zoom in or dow to zoom out. 3. Press the ESC key to end zooming or right click the mouse and choose EXIT from the pop-up menu **To zoom in on an area by defining a window.** 1. In the command line, type Z press Enter or click the Zoom Window in the standard toolbar or choose Zoom the Window from the View Menu. 2. Specify one corner of the area you want to view. 3. Specify the opposite corner of the area you want to view. **Displaying the previous view** 1. In the command line, type Z press Enter type P then press Entr or click the zoom Previous icon in the standard toolbar, or choose Zoom the Previous from the View Menu **Other Zooming Options** Zooms in display twice relative to the current size **All** THE **PAN** COMMAND The Pan command of AutoCAD moves the drawing around the drawing window without changing its magnification. This helps you view objects located outside the drawing window using the current view size. **Panning the drawing interactively** 1. In the command line type P or choose Pan the Real Time from the View Menu. Or click pan Realtime icon on the Standard Toolbar. The cursor changes into Pan Realtime Icon. 2. Hold down the left mouse button and drag it around the drawing window. The drawing follows dynamically. 3. Press ESC key or right click the mouse then choose exit from the pop-up menu to end panning. **YOUR FIRST DRAWING EXERCISE** For your first drawing exercise you shall be ask to open template files to complete the drawing shown on the second and third activity sheets for exercises on making lines, rectangle and other polygons, circles and arc using objects snaps options. 1. TRIM AND EXTEND COMMAND 2. OBJECT SNAPS EXERCISE 3. CIRCLE EXERCISE Please see other copy of the above exercises. DRAWING AIDS Grid Grids are visual guides which can help in measuring and aligning objects as they are created or modified in your drawing window. You can display Grids or hide them fast by using either the F7 function key, or by double- clicking at the GRID box at the status Bar. Or by typing the GRID then pressing Enter, then type ON or OFF. Snap You can snap precisely to these grids for accurate positioning or measurements by turning on the Snap Mode quickly using the F9 function key, or by double clicking at the Snap Box at the at the Status Bar, or by typing Snap then pressing Enter, then type ON or OFF. Ortho Mode As you draw lines or move objects, you can use ORTHO Mode to restrict the cursor to the horizontal or vertical axes. (The alignment actually depends on the current snap angle or UCS). As you move the cursor, rubber band line defines the displacement follows the horizontal or vertical axis, depending on which axis is nearest to the cursor. AutoCAD ignores the ORTHO mode when you enter coordinates on the command line. You can invoke the ORTHO mode quickly by using the F8 function key, or by clicking at the ORTHO box at the status bar, or by typing ORTHO then press enter, then type ON or OFF, or by checking the check box for ORTHO at the Drawing Aids Dialog Box. **The COORDINATES SYSTEM** When the computer prompts you for a point you can use the mouse to specify its CARTESIAN COORDINATES Has three axes X,Y, and Z. At this stage we shall deal with the X and Y axes only. When you enter coordinate values you indicate the point's direction (+ or -) along the X and Y direction and its distance relative to the origin(0,0,0). When you begin a new drawing in autoCAD you are automatically in the world Coordinate System (WCS) which set the X axis horizontal and the Y axis vertical with the default origin at the lower left corner of the drawing window. AutoCAD displays the current cursor's coordinates in the status bar in three (3) types of coordinate display. Use F6 function key to cycle through these three options. 1. Dynamic display - updates the Cartesian coordinates in the Coordinate Display box of the status bar. This the default option. 2. Static display - updates Cartesian coordinate only when a point is specified or clicked. 3. Distance and angle display- updates polar coordinates as the cursor is moved. **ABSOLUTE COORDINATE** When the coordinates to be inputted use the origin or the **datum** of the Current Coordinate System as the reference point, these are considered as **Absolute Coordinate.** They are simply typed in the command line like -3,5 9,7 and 5-3. The first value is for **X** and the second is for **Y**: **it has to be in this order of input.** **RELATIVE COORDINATE** When the coordinates to be inputted use the last point established as the reference point, these are considered as **Relative Coordinates**. See examples below. When inputting these coordinates at the command line precede their values with the @ character, e.g. \@4,0 @-8,10 and \@7,-3. This is rather the most convenient coordinate system to use. **POLAR COORDINATES** When angles are involved in directions for locating points this is the Coordinate system to use. To enter a Polar Coordinate, enter a distance and an angle, separated by an angle bracket (\