First Level 2D Fundamentals - SDC Publications

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AutoCAD 2016 Tutorial First Level 2D FundamentalsRandy H. ShihSDCP U B L I C AT I O N SBetter Textbooks. Lower Prices.www.SDCpublications.com

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AutoCAD 2016 Tutorial: 2D FundamentalsChapter 1AutoCAD Fundamentals Create and Save AutoCAD drawing files Use the AutoCAD visual referencecommands Draw, using the LINE and CIRCLEcommands Use the ERASE command Define Positions using the Basic Entrymethods Use the AutoCAD Pan Realtime option1-1

1-2AutoCAD 2016 Tutorial: 2D FundamentalsAutoCAD Certified User Examination Objectives CoverageThis table shows the pages on which the objectives of the Certified User Examination arecovered in Chapter 1.Section 1: Controlling the Display in DrawingsPrecision.1-6Zoom Extent.1-7Drawing LIMITS .1-6Status Bar .1-10GRID Display .1-10, 1-11PAN Realtime .1-20Certified User Reference GuideSection 2: Creating Basic DrawingsFormat .1-5Units Setup .1-5LINE Command .1-8Coordinates .1-8Interactive Input Method.1-10SNAP Option .1-12World Space .1-15User Coordinate System .1-15World Coordinate System .1-15UCS Icon Display .1-16TTR, Circle .1-23Relative Coordinate .1-17Coordinate Systems .1-17Cartesian coordinate system .1-17Absolute Coordinates .1-17, 1-18Positions, Defining.1-18LINE, Close Option .1-19CIRCLE Command.1-23TTT, Circle .1-23ARC Command .1-33Section 3: Manipulating ObjectsERASE Command .1-13Selection Window .1-14

AutoCAD Fundamentals1-3IntroductionLearning to use a CAD system is similar to learning a new language. It is necessary tobegin with the basic alphabet and learn how to use it correctly and effectively throughpractice. This will require learning some new concepts and skills as well as learning adifferent vocabulary. Today, the majority of the Mechanical CAD systems are capable ofcreating three-dimensional solid models. Nonetheless, all CAD systems create designsusing basic geometric entities and many of the constructions used in technical designs arebased upon two-dimensional planar geometry. The method and number of operations thatare required to accomplish the basic planar constructions are different from one system toanother.In order to become effective and efficient in using a CAD system, we must learn to creategeometric entities quickly and accurately. In learning to use a CAD system, lines andcircles are the first two, and perhaps the most important two, geometric entities that oneshould master the skills of creating and modifying. Straight lines and circles are used inalmost all technical designs. In examining the different types of planar geometric entities,the importance of lines and circles becomes obvious. Triangles and polygons are planarfigures bounded by straight lines. Ellipses and splines can be constructed by connectingarcs with different radii. As one gains some experience in creating lines and circles,similar procedures can be applied to create other geometric entities. In this chapter, thedifferent ways of creating lines and circles in AutoCAD 2016 are examined.Starting Up AutoCAD 20161. Select the AutoCAD 2016 option on the Program menu or select the AutoCAD2016 icon on the Desktop. Click Start Drawing to start a new drawing. Once the program is loaded into memory, the AutoCAD 2016 main drawingscreen will appear on the screen.

1-4AutoCAD 2016 Tutorial: 2D Fundamentals Note that AutoCAD automatically assigns generic names, Drawing X, as newdrawings are created. In our example, AutoCAD opened the graphics window usingthe default system units and assigned the drawing name Drawing1.2. If necessary, click on the down-arrow in the Quick Access bar and select ShowMenu Bar to display the AutoCAD Menu Bar. The Menu Bar provides accessto all AutoCAD commands.3. To switch on the AutoCAD Coordinates Display, use the Customization optionat the bottom right corner.

AutoCAD Fundamentals1-5Drawing Units Setup Every object we construct in a CAD system is measured in units. We shoulddetermine the system of units within the CAD system before creating the firstgeometric entities.1. In the Menu Bar select:[Format] [Units] The AutoCAD Menu Bar contains multiple pull-downmenus where all of the AutoCAD commands can beaccessed. Note that many of the menu items listed inthe pull-down menus can also be accessed through theQuick Access toolbar and/or Ribbon panels.2. Click on the LengthType option to displaythe different types oflength units available.Confirm the LengthType is set toDecimal.3. On your own, examine the other settings that areavailable.4. In the Drawing Units dialog box, set the Length Type to Decimal. This will setthe measurement to the default English units, inches.

1-6AutoCAD 2016 Tutorial: 2D Fundamentals5. Set the Precision to two digitsafter the decimal point as shown inthe above figure.6. Pick OK to exit the Drawing Unitsdialog box.Drawing Area Setup Next, we will set up the Drawing Limits by entering a command in thecommand prompt area. Setting the Drawing Limits controls the extents of thedisplay of the grid. It also serves as a visual reference that marks the workingarea. It can also be used to prevent construction outside the grid limits and as aplot option that defines an area to be plotted/printed. Note that this setting doesnot limit the region for geometry construction.1. In the Menu Bar select:[Format] [Drawing Limits]2. In the command prompt area, the message “Reset ModelSpace Limits: Specify lower left corner or [On/Off] 0.00,0.00 :” is displayed. Press the ENTER key once toaccept the default coordinates 0.00,0.00 .3. In the command prompt area, the message “Specify upper right corner 12.00,9.00 :” is displayed. Press the ENTER key again to accept the defaultcoordinates 12.00,9.00 .

AutoCAD Fundamentals1-74. On your own, move the graphics cursor near the upper-right corner inside thedrawing area and note that the drawing area is unchanged. (The Drawing Limitscommand is used to set the drawing area, but the display will not be adjusted untila display command is used.)5. Inside the Menu Bar area select:[View] [Zoom] [All] The Zoom All command willadjust the display so that allobjects in the drawing aredisplayed to be as large aspossible. If no objects areconstructed, the DrawingLimits are used to adjust thecurrent viewport.6. Move the graphics cursor near the upper-right corner inside the drawing area andnote that the display area is updated.7. Hit the function key [F7] once to turn off the display of the Grid lines. Note that function key [F7] is a quick key, which can be used to quickly toggleon/off the grid display. Also, note the command prompt area can be positioned todock below the drawing area or float inside the drawing area as shown.

1-8AutoCAD 2016 Tutorial: 2D FundamentalsDrawing Lines with the LINE Command1. Move the graphics cursor to the first icon in theDraw panel. This icon is the Line icon. Note thata brief description of the Line command appearsnext to the cursor.2. Select the icon by clicking once with the leftmouse-button, which will activate the Linecommand.3. In the command prompt area, near the bottom of the AutoCAD drawing screen,the message “ line Specify first point:” is displayed. AutoCAD expects us toidentify the starting location of a straight line. Move the graphics cursor inside thegraphics window and watch the display of the coordinates of the graphics cursorat the bottom of the AutoCAD drawing screen. The three numbers represent thelocation of the cursor in the X, Y, and Z directions. We can treat the graphicswindow as if it was a piece of paper and we are using the graphics cursor as if itwere a pencil with which to draw.Coordinates of the graphicscursor53214 We will create a freehand sketch of a fivepoint star using the Line command. Do not beoverly concerned with the actual size oraccuracy of your freehand sketch. Thisexercise is to give you a feel for the AutoCAD2016 user interface.

AutoCAD Fundamentals1-94. We will start at a location about one-thirdfrom the bottom of the graphics window.Left-click once to position the startingpoint of our first line. This will be point 1of our sketch. Next, move the cursorupward and toward the right side of point1. Notice the rubber-band line that followsthe graphics cursor in the graphicswindow. Left-click again (point 2) and wehave created the first line of our sketch.5. Move the cursor to the left of point 2 andcreate a horizontal line about the samelength as the first line on the screen.536. Repeat the above steps and complete thefreehand sketch by adding three morelines (from point 3 to point 4, point 4 topoint 5, and then connect to point 5 backto point 1).2147. Notice that the Line command remains activated evenafter we connected the last segment of the line to thestarting point (point 1) of our sketch. Inside the graphicswindow, click once with the right-mouse-button and apopup menu appears on the screen.8. Select Enter with the left-mouse-button to end the Linecommand. (This is equivalent to hitting the [ENTER] keyon the keyboard.)9. Move the cursor near point 2 and point 3, and estimate thelength of the horizontal line by watching the displayedcoordinates for each point.

1-10AutoCAD 2016 Tutorial: 2D FundamentalsVisual ReferenceThe method we just used to create the freehand sketch is known as the interactivemethod, where we use the cursor to specify locations on the screen. This method isperhaps the fastest way to specify locations on the screen. However, it is rather difficultto try to create a line of a specific length by watching the displayed coordinates. It wouldbe helpful to know what one inch or one meter looks like on the screen while we arecreating entities. AutoCAD 2016 provides us with many tools to aid the construction ofour designs. For example, the GRID and SNAP MODE options can be used to get avisual reference as to the size of objects and learn to restrict the movement of the cursorto a set increment on the screen.The GRID and SNAP MODE options can be turned ON or OFF through the Status Bar.The Status Bar area is located at the bottom left of the AutoCAD drawing screen, next tothe cursor coordinates.Option ButtonsThe second button in the Status Bar is the SNAP MODE option and the third button is theGRID DISPLAY option. Note that the buttons in the Status Bar area serve two functions:(1) the status of the specific option, and (2) as toggle switches that can be used to turnthese special options ON and OFF. When the corresponding button is highlighted, thespecific option is turned ON. Using the buttons is a quick and easy way to make changesto these drawing aid options. The buttons in the Status Bar can also be switched on andoff in the middle of another command.

AutoCAD Fundamentals1-11GRID ON1. Left-click the GRID button in the Status Bar to turn ON the GRID DISPLAYoption. (Notice in the command prompt area, the message “ Grid on ” is alsodisplayed.)2. Move the cursor inside the graphics window, and estimate the distance in betweenthe grid lines by watching the coordinates displayed at the bottom of the screen. The GRID option creates a pattern of lines that extends over an area on the screen.Using the grid is similar to placing a sheet of grid paper under a drawing. The gridhelps you align objects and visualize the distance between them. The grid is notdisplayed in the plotted drawing. The default grid spacing, which means the distancein between two lines on the screen, is 0.5 inches. We can see that the sketchedhorizontal line in the sketch is about 4 inches long.

1-12AutoCAD 2016 Tutorial: 2D FundamentalsSNAP MODE ON1. Left-click the SNAP MODE button in the Status Bar to turn ON the SNAP option.2. Move the cursor inside the graphics window, and move the cursor diagonally onthe screen. Observe the movement of the cursor and watch the coordinatesdisplay at the bottom of the screen. The SNAP option controls an invisible rectangular grid that restricts cursormovement to specified intervals. When SNAP mode is on, the screen cursor andall input coordinates are snapped to the nearest point on the grid. The default snapinterval is 0.5 inches and aligned to the grid points on the screen.3. Click on the Line icon in the Draw toolbar.In the command prompt area, the messa

1-4 AutoCAD 2016 Tutorial: 2D Fundamentals Note that AutoCAD automatically assigns generic names, Drawing X, as new drawings are created. In our example, AutoCAD opened the graphics window using the default system units and assigned the drawing name Drawing1. 2. If necessary, click on the down-arrow in the Quick Access bar and select Show Menu Bar to display the AutoCAD Menu Bar. The