{"id":348,"date":"2021-01-27T14:50:52","date_gmt":"2021-01-27T19:50:52","guid":{"rendered":"https:\/\/opentextbc.ca\/autocad2d\/chapter\/circles-and-arcs\/"},"modified":"2021-11-03T16:42:16","modified_gmt":"2021-11-03T20:42:16","slug":"circles-and-arcs","status":"publish","type":"chapter","link":"https:\/\/opentextbc.ca\/autocad2d\/chapter\/circles-and-arcs\/","title":{"raw":"Module 7: Circles and Arcs","rendered":"Module 7: Circles and Arcs"},"content":{"raw":"
\n

Learning Outcomes<\/p>\n\n<\/header>\n

\n\nWhen you have completed this module, you will be able to:\n
    \n \t
  1. Describe the geometry of circles and arcs.<\/li>\n \t
  2. Apply the CIRCLE and ARC commands to draw circles and arcs.<\/li>\n \t
  3. Describe how to undo a command or redo an undo.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

    Geometry Lesson: Circles<\/h1>\nA circle <\/em><\/span>is defined as a closed curve in which all points are the same distance from its center point. The center point is a single XY coordinate.\n\nA circle is 360 degrees and can be divided into four quadrants<\/em><\/span>. All points on a circle are at a given distance from is center point. The distance between any of the points and the center is called the radius<\/em><\/span>.\n\nStudy the drawings in Figure 7-1, 7-2, 7-3, and 7-4 for a description of the geometry of a circle.\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"393\"]\"\" Figure 7-1 Geometry of a Circle - Part 1[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"381\"]\"\" Figure 7-2 Geometry of a Circle - Part 2[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"374\"]\"\" Figure 7-3 Geometry of a Circle - Part 3[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"329\"]\"\" Figure 7-4 Geometry of a Circle - Part 4[\/caption]\n

    Geometry Lesson: Arcs<\/span><\/h1>\nAn arc<\/span> <\/em>is defined as an open curve in which all points are the same distance from its center point. Study the drawings in Figure 7-5 and 7-6.for a description of the geometry of an arc.\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"686\"]\"\" Figure 7-5 Geometry of an Arc - Part 1[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"695\"]\"\" Figure 7-6 Geometry of an Arc - Part 2[\/caption]\n\n
    \n

    AutoCAD Command: CIRCLE<\/p>\n\n<\/header>\n

    \n\nThe CIRCLE command is used to draw circles.\n\nShortcut: C<\/strong>\n\n<\/div>\n<\/div>\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"373\"]\"\" Draw Toolbar[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"344\"]\"\" Draw Pull-down[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"228\"]\"\" Home Ribbon[\/caption]\n\n
    \n

    AutoCAD Command: ARC<\/p>\n\n<\/header>\n

    \n\nThe ARC command is used to draw arcs.\n\nShortcut: A<\/strong>\n\n<\/div>\n<\/div>\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"325\"]\"\" Draw Toolbar[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"371\"]\"\" Draw Pull-down[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"229\"]\"\" Home Ribbon[\/caption]\n\n
    MUST KNOW: <\/strong>When you are drawing arcs, it is best to specify the center point first and the start point second. The radius and the direction of the arc can be entered at the same time. Enter the angle or the end point to complete the arc.\n\n[caption id=\"attachment_320\" align=\"aligncenter\" width=\"345\"]\"\" Figure 7-7 Constructing an Arc[\/caption]\n\nCommand: ARC<\/strong>\n\nSpecify start point of arc or [Center]: C <\/strong>\n\nSpecify center point of arc: 3,4 <\/strong>\n\nSpecify start point of arc: @0,-2<\/strong>\n\n(Specifying the radius and the direction for the start point.)<\/em>\n\nSpecify end point of arc or [Angle\/chord Length]: A<\/strong>\n\nSpecify included angle: 180<\/strong>\n\nCommand:\n\n<\/div>\n

    WORKALONG: Drawing Circles and Arcs<\/h1>\n

    Step 1<\/h2>\nStart a new drawing using the template: 2D English.<\/span>\n

    Step 2<\/h2>\nSave and name the drawing: AutoCAD 2D Workalong 07-1<\/span>.\n

    Step 3<\/h2>\nCreate layer: Object<\/span>, color red. Set it as the current layer. (Figure Step 3)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"666\"]\"\" Figure Step 3[\/caption]\n

    Step 4<\/h2>\nUsing the figures and what you already leaned, draw the two lines shown in Figure Step 4B. (Figure Step 4A and 4B)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"532\"]\"\" Figure Step 4A[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"210\"]\"\" Figure Step 4B[\/caption]\n\n
    AUTHOR'S COMMENTS:<\/strong> Draw the two lines using the LINE command twice.<\/div>\n
    USER TIP:<\/strong> By default, AutoCAD draw arcs counterclockwise which is the positive arc angle. If you use the Angle option, AutoCAD allows you to draw an arc by entering a negative angle.<\/div>\n

    Step 5<\/h2>\nEnter the ARC command, as shown below, to draw the arc. (Figure Step 5)\n\nCommand: ARC<\/strong>\n\nSpecify start point of arc or [Center]:\u00a0C<\/strong>\n\n(If possible, always draw arcs starting with the center point first.)<\/em><\/span>\n\nSpecify center point of arc: 2.5, 5<\/strong>\n\n(Enter the center point.)<\/em><\/span>\n\nSpecify start point of arc: @4,0<\/strong>\n\n(Enter the start point. Here the trick is to give AutoCad the start point and the radius of the arc at the same time)<\/em><\/span>\n\nSpecify end point of arc or [Angle\/chord Length]: A<\/strong>\n\nSpecify included angle: 90<\/strong>\n\n(Enter the angle of the arc. In this case, it is 90 degrees.)<\/em><\/span>\n\nCommand:\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"316\"]\"\" Figure Step 5[\/caption]\n\n
    USER TIP: <\/strong>Arcs can be drawn in either counterclockwise or clockwise direction by holding down the CTRL key, while in the ARC command, to reverse the direction.<\/div>\n

    Step 6<\/h2>\nEnter the CIRCLE command, as shown below, to draw the four circles to complete the drawing. (Figure Step 6A and 6B)\n\nCommand: CIRCLE<\/strong>\n\nSpecify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: 3.5,6<\/strong>\n\n(Since this is the first circle, enter an absolute coordinate for the center point.)<\/em><\/span>\n\nSpecify radius of circle or [Diameter]: D<\/strong>\n\n(Circles are usually dimensioned with diameters rather then a radius, enter D)<\/em><\/span>\n\nSpecify diameter of circle: 0.65<\/strong>\n\nCommand: CIRCLE<\/strong>\n\n(Press Enter or Space bar as that will repeat the last command.)<\/em><\/span>\n\nSpecify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @1,0<\/strong>\n\n(Notice here, since AutoCAD always remembers the lastpoint, use an @. The lastpoint was the center of the first circle placed.)<\/em><\/span>\n\nSpecify radius of circle or [Diameter] <0.3250>: D<\/strong>\n\nSpecify diameter of circle <0.6500>: 0.75<\/strong>\n\nCommand: CIRCLE <\/strong>(Press Enter or Space bar as that will repeat the last command.\n\nSpecify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @0,1.5<\/strong>\n\n(Use an @ from the center of the last circle drawn.) <\/em><\/span>\n\nSpecify radius of circle or [Diameter] <0.3750>: D <\/strong>\n\nSpecify diameter of circle <0.7500>: 1<\/strong>\n\nCommand: CIRCLE<\/strong>\n\n(Press Enter or Space bar. That will repeat the last command and save you entering it again.)<\/em><\/span>\n\nSpecify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @-1,0<\/strong>\n\nSpecify radius of circle or [Diameter] <0.5000>: D <\/strong>\n\nSpecify diameter of circle <1.0000>: 0.5 <\/strong>\n\nCommand:\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"186\"]\"\" Figure Step 6A[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"186\"]\"\" Figure Step 6B[\/caption]\n

    Step 7<\/h2>\nSave and close the drawing.\n

    WORKALONG: Drawing Circles Using the TTR Option<\/h1>\n

    Step 1<\/h2>\nStart a new drawing using the template: 2D English<\/span>.\n

    Step 2<\/h2>\nSave and name the drawing: AutoCAD 2D Workalong 07-2<\/span>.\n

    Step 3<\/h2>\nCreate layer: Object<\/span>, color red. Set it as the current layer. (Figure Step 3)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"500\"]\"\" Figure Step 3[\/caption]\n

    Step 4<\/h2>\nUsing the dimensioned drawing as a guide and what you already learned, use the LINE command to draw the four outside lines. (Figure Step 4A and 4B)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"550\"]\"\" Figure Step 4A[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"284\"]\"\" Figure Step 4B[\/caption]\n

    Step 5<\/h2>\nEnter the CIRCLE command and the TTR option, as shown below, to insert the 2 inch diameter circle. (Figure Step 5A and 5B)\n\nCommand: CIRCLE<\/strong>\n\nSpecify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: TTR<\/strong>\n\nSpecify point on object for first tangent of circle: P1<\/strong>\n\n(Using the graphic cursor, move it on the top horizontal line. When the tangent snap icon appears, press the left mouse button.)<\/em><\/span>\n\nSpecify point on object for second tangent of circle: P2<\/strong>\n\n(Move the cursor on the vertical line. When the tangent icon appears, pick it.)<\/em><\/span>\n\nSpecify radius of circle <0.7000>: 1<\/strong>\n\n(Enter the radius of the circle. Be careful, since circles are usually dimensioned in diameters you will have to divide it in half.)<\/em><\/span>\n\nCommand:\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"283\"]\"\" Figure Step 5A[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"256\"]\"\" Figure Step 5B[\/caption]\n\n
    \n\nAUTHOR'S COMMENTS: <\/strong>TTR means ' Tangent Tangent Radius '. Do not enter the P1 or P2 on the keyboard. They simply mean Pick 1 and Pick 2. To pick, move the Graphic cursor to the desired location, wait for the tangent Autosnap marker to display and when it dose, press the left mouse button.\n\n<\/div>\n

    Step 6<\/h2>\nEnter the CIRCLE command and the TTR option, as shown below, to insert the 2.5 inch diameter circle. (Figure Step 6A and 6B)\n\nCommand: CIRCLE<\/strong>\n\nSpecify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: TTR<\/strong>\n\nSpecify point on object for first tangent of circle: P3 <\/strong>Specify point on object for second tangent of circle: P4 <\/strong>Specify radius of circle <1.0000>: 1.25<\/strong>\n\nCommand:\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"285\"]\"\" Figure Step 6A[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"256\"]\"\" Figure Step 6B[\/caption]\n\n
    AUTHOR'S COMMENTS: <\/strong>Keep in mind that you do not enter the P3 or P4 on the keyboard. They simply mean Pick 3 and Pick 4 of this workalong.<\/div>\n

    Step 7<\/h2>\nEnter the CIRCLE command and the TTR option, as shown below, to insert the middle 2 diameter circle. (Figure Step 7A and 7B)\n\nCommand: CIRCLE<\/strong>\n\nSpecify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: TTR<\/strong>\n\nSpecify point on object for first tangent of circle: P5 <\/strong>\n\nSpecify point on object for second tangent of circle: P6 <\/strong>\n\nSpecify radius of circle <1.2500>: 1<\/strong>\n\nCommand:\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"256\"]\"\" Figure Step 7A[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"256\"]\"\" Figure Step 7B[\/caption]\n

    Step 8<\/h2>\nSave and close the drawing.\n
    \n\nMUST KNOW:<\/strong> A very useful feature in AutoCAD is being able to undo a command or redo an undo. All of the commands in the current drawing session can be undone, one at a time. The last undo only can be reversed with a redo.To undo the last command, enter the U command, press CTRL+Z, or click the icon as shown in the figure on the right.\n\nCommand: U<\/strong>\n\nIf more then one U is entered, it will step back one command at time. This is useful if you made an error several commands earlier.\n\nCommand: U <\/strong>\n\nCommand: U <\/strong>\n\nCommand: U<\/strong>\n\n\"\"\n\nEnter the REDO command, press CTRL+Y, or click the icon as shown in the figure on the right to redo the undo. The redo will undo the last undo only.\n\nCommand: REDO<\/strong>\n\n\"\"\n\n<\/div>\n

    Drafting Lesson: Reading Dimensions for Circles and Arcs<\/h1>\nCircles and arcs are dimensioned as follows:\n\nCircles are dimensioned with their diameter. For example: 2.0 DIA.\n\nArcs are dimensioned with their radius.\n\nFor example: 1.5 R\n\nWhen there is more than one circle of the same diameter, it is only dimensioned once. For example: 0.5 DIA., 4 PLACES\n\nSometimes multiple arcs are dimensioned as typical<\/span> <\/em>(TYP.). For example: 2.0 R TYP. Typical simply means that there is at least one more arc of the same size. See Figure 7-8\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"565\"]\"\" Figure 7-8 Reading Dimensions[\/caption]\n

    Key Principles<\/h1>\n
    \n

    Key Principles in Module 7<\/p>\n\n<\/header>\n

    \n
      \n \t
    1. A circle is 360 degrees and can be divided into four quadrants.<\/li>\n \t
    2. All points on a circle are at a given distance from is center point.<\/li>\n \t
    3. An arc is defined as an open curve in which all points are the same distance from its center point.<\/li>\n \t
    4. By default, AutoCAD draws arcs counterclockwise.<\/li>\n \t
    5. When drawing arcs it is best to specify the center point first, the start point that sets the radius second, and an angle to locate the endpoint third.<\/li>\n \t
    6. A very useful feature in AutoCAD is being able to undo a command or redo an undo.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

      Lab Exercise 7-1<\/h1>\nTime allowed: 40 minutes.\n\n\n\n\n
      Drawing Name<\/th>\nTemplate<\/th>\nUnits<\/th>\n<\/tr>\n
      AutoCAD 2D Lab 07-1<\/td>\n2D English<\/td>\nInches<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n
      Layering Scheme<\/span><\/caption>\n
      Layer Name<\/th>\nObjects on Layer<\/th>\nColor<\/th>\n<\/tr>\n
      Object<\/td>\nAll lines, circles and arcs<\/td>\nRed<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Step 1<\/h2>\nStart a new drawing using the template shown above.\n

      Step 2<\/h2>\nSave and name the drawing with the name shown above.\n

      Step 3<\/h2>\nSetup the layers using the Layering Scheme shown above.\n

      Step 4<\/h2>\nDraw the object shown in the figure. In this drawing, all objects should be on layer: Object<\/span> and display red. (Figure Step 4A and 4B)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"137\"]\"\" Figure Step 4A
      Completed Drawing[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"548\"]\"\" Figure Step 4B[\/caption]\n

      Step 5<\/h2>\nEnter the UNITS command. In the Units dialogue box, set the Insertion Units to Inches.\n

      Step 6<\/h2>\nCheck the drawing's accuracy with the key.\n

      Step 7<\/h2>\nIf there are any errors, turn layer: Key off and correct the drawing. If necessary, start a new drawing and draw it again.\n

      Step 8<\/h2>\nTurn layer Key on. If the drawing still inaccurate, go back to Step 7.\n

      Step 9<\/h2>\nTurn layer Key off.\n

      Step 10<\/h2>\nSave and close the drawing.\n
      \n\nAUTHOR'S CONSTRUCTION TECHNIQUES: <\/strong>The following steps are the construction technique suggested by the author to help you learn how to construct objects using AutoCAD. It is only the suggested method and if you can complete the drawing accurately using a different construction technique, that is what is important. You may want to compare your construction technique with the authors.\n\n<\/div>\n\"\"\n
      \n\nAUTHOR'S CONSTRUCTION HINTS: <\/strong>Do your best to complete the lab exercise drawing without using the following hint. If you get stuck and cannot complete it on your own, use the following hint to help you.\n\n<\/div>\n

      Hint 1<\/h2>\n(Figure Hint 1)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"476\"]\"\" Figure Hint 1[\/caption]\n

      Lab Exercise 7-2<\/h1>\nTime allowed: 40 minutes.\n\n\n\n\n
      Drawing Name<\/th>\nTemplate<\/th>\nUnits<\/th>\n<\/tr>\n
      AutoCAD 2D Lab 07-2<\/td>\n2D Metric<\/td>\nMillimeters<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n
      Layering Scheme<\/span><\/caption>\n
      Layer Name<\/th>\nObjects on Layer<\/th>\nColor<\/th>\n<\/tr>\n
      Object<\/td>\nAll lines, circles and arcs<\/td>\nRed<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

      Step 1<\/h2>\nStart a new drawing using the template shown above.\n

      Step 2<\/h2>\nSave and name the drawing with the name shown above.\n

      Step 3<\/h2>\nSetup the layers using the Layering Scheme shown above.\n

      Step 4<\/h2>\nDraw the object shown in the figure. In this drawing, all objects should be on layer: Object and display red. (Figure Step 4A and 4B)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"140\"]\"\" Figure Step 4A
      Completed Drawing[\/caption]\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"400\"]\"\" Figure Step 4B[\/caption]\n

      Step 5<\/h2>\nEnter the UNITS command. In the Units dialogue box, set the Insertion Units to Millimeters.\n

      Step 6<\/h2>\nCheck the drawing's accuracy with the key.\n

      Step 7<\/h2>\nIf there are any errors, turn layer Key off and correct the drawing. If necessary, start a new drawing and draw it again.\n

      Step 8<\/h2>\nTurn layer: Key<\/span> on. If the drawing still inaccurate, go back to Step 7.\n

      Step 9<\/h2>\nTurn layer: Key<\/span> off.\n

      Step 10<\/h2>\nSave and close the drawing.\n
      \n\nAUTHOR'S CONSTRUCTION TECHNIQUES: <\/strong>The following steps are the construction technique suggested by the author to help you learn how to construct objects using AutoCAD. It is only the suggested method and if you can complete the drawing accurately using a different construction technique, that is what is important. You may want to compare your construction technique with the authors.\n\n<\/div>\n\"\"\n
      \n\nAUTHOR'S CONSTRUCTION HINTS: <\/strong>Do your best to complete the lab exercise drawing without using the following hints. If you get stuck and cannot complete it on your own, use the following hints to help you.\n\n<\/div>\n

      Hint 1\n<\/strong><\/h2>\nDraw the two circles using the TTR option. (Figure Hint 1)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"232\"]\"\" Figure Hint 1[\/caption]\n

      Hint 2<\/h2>\nDraw the four smaller circles using the @ as shown below. (Figure Hint 2)\n\n[caption id=\"attachment_347\" align=\"aligncenter\" width=\"385\"]\"\" Figure Hint 2[\/caption]\n\nCommand: C<\/strong>\n\nCIRCLE Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: 85,170<\/strong>\n\nSpecify radius of circle or [Diameter]: D <\/strong>\n\nSpecify diameter of circle: 10 <\/strong>\n\nCommand: C<\/strong>\n\nCIRCLE Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @40,0<\/strong>\n\nSpecify radius of circle or [Diameter] <5.0000>:\n\nCommand: C<\/strong>\n\nCIRCLE Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @0,20<\/strong>\n\nSpecify radius of circle or [Diameter] <5.0000>:\n\nCommand: C<\/strong>\n\nCIRCLE Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @-40,0<\/strong>\n\nSpecify radius of circle or [Diameter] <5.0000>:\n\nCommand:","rendered":"
      \n
      \n

      Learning Outcomes<\/p>\n<\/header>\n

      \n

      When you have completed this module, you will be able to:<\/p>\n

        \n
      1. Describe the geometry of circles and arcs.<\/li>\n
      2. Apply the CIRCLE and ARC commands to draw circles and arcs.<\/li>\n
      3. Describe how to undo a command or redo an undo.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

        Geometry Lesson: Circles<\/h1>\n

        A circle <\/em><\/span>is defined as a closed curve in which all points are the same distance from its center point. The center point is a single XY coordinate.<\/p>\n

        A circle is 360 degrees and can be divided into four quadrants<\/em><\/span>. All points on a circle are at a given distance from is center point. The distance between any of the points and the center is called the radius<\/em><\/span>.<\/p>\n

        Study the drawings in Figure 7-1, 7-2, 7-3, and 7-4 for a description of the geometry of a circle.<\/p>\n

        \"\"
        Figure 7-1 Geometry of a Circle – Part 1<\/figcaption><\/figure>\n
        \"\"
        Figure 7-2 Geometry of a Circle – Part 2<\/figcaption><\/figure>\n
        \"\"
        Figure 7-3 Geometry of a Circle – Part 3<\/figcaption><\/figure>\n
        \"\"
        Figure 7-4 Geometry of a Circle – Part 4<\/figcaption><\/figure>\n

        Geometry Lesson: Arcs<\/span><\/h1>\n

        An arc<\/span> <\/em>is defined as an open curve in which all points are the same distance from its center point. Study the drawings in Figure 7-5 and 7-6.for a description of the geometry of an arc.<\/p>\n

        \"\"
        Figure 7-5 Geometry of an Arc – Part 1<\/figcaption><\/figure>\n
        \"\"
        Figure 7-6 Geometry of an Arc – Part 2<\/figcaption><\/figure>\n
        \n
        \n

        AutoCAD Command: CIRCLE<\/p>\n<\/header>\n

        \n

        The CIRCLE command is used to draw circles.<\/p>\n

        Shortcut: C<\/strong><\/p>\n<\/div>\n<\/div>\n

        \"\"
        Draw Toolbar<\/figcaption><\/figure>\n
        \"\"
        Draw Pull-down<\/figcaption><\/figure>\n
        \"\"
        Home Ribbon<\/figcaption><\/figure>\n
        \n
        \n

        AutoCAD Command: ARC<\/p>\n<\/header>\n

        \n

        The ARC command is used to draw arcs.<\/p>\n

        Shortcut: A<\/strong><\/p>\n<\/div>\n<\/div>\n

        \"\"
        Draw Toolbar<\/figcaption><\/figure>\n
        \"\"
        Draw Pull-down<\/figcaption><\/figure>\n
        \"\"
        Home Ribbon<\/figcaption><\/figure>\n
        MUST KNOW: <\/strong>When you are drawing arcs, it is best to specify the center point first and the start point second. The radius and the direction of the arc can be entered at the same time. Enter the angle or the end point to complete the arc.<\/p>\n
        \"\"
        Figure 7-7 Constructing an Arc<\/figcaption><\/figure>\n

        Command: ARC<\/strong><\/p>\n

        Specify start point of arc or [Center]: C <\/strong><\/p>\n

        Specify center point of arc: 3,4 <\/strong><\/p>\n

        Specify start point of arc: @0,-2<\/strong><\/p>\n

        (Specifying the radius and the direction for the start point.)<\/em><\/p>\n

        Specify end point of arc or [Angle\/chord Length]: A<\/strong><\/p>\n

        Specify included angle: 180<\/strong><\/p>\n

        Command:<\/p>\n<\/div>\n

        WORKALONG: Drawing Circles and Arcs<\/h1>\n

        Step 1<\/h2>\n

        Start a new drawing using the template: 2D English.<\/span><\/p>\n

        Step 2<\/h2>\n

        Save and name the drawing: AutoCAD 2D Workalong 07-1<\/span>.<\/p>\n

        Step 3<\/h2>\n

        Create layer: Object<\/span>, color red. Set it as the current layer. (Figure Step 3)<\/p>\n

        \"\"
        Figure Step 3<\/figcaption><\/figure>\n

        Step 4<\/h2>\n

        Using the figures and what you already leaned, draw the two lines shown in Figure Step 4B. (Figure Step 4A and 4B)<\/p>\n

        \"\"
        Figure Step 4A<\/figcaption><\/figure>\n
        \"\"
        Figure Step 4B<\/figcaption><\/figure>\n
        AUTHOR’S COMMENTS:<\/strong> Draw the two lines using the LINE command twice.<\/div>\n
        USER TIP:<\/strong> By default, AutoCAD draw arcs counterclockwise which is the positive arc angle. If you use the Angle option, AutoCAD allows you to draw an arc by entering a negative angle.<\/div>\n

        Step 5<\/h2>\n

        Enter the ARC command, as shown below, to draw the arc. (Figure Step 5)<\/p>\n

        Command: ARC<\/strong><\/p>\n

        Specify start point of arc or [Center]:\u00a0C<\/strong><\/p>\n

        (If possible, always draw arcs starting with the center point first.)<\/em><\/span><\/p>\n

        Specify center point of arc: 2.5, 5<\/strong><\/p>\n

        (Enter the center point.)<\/em><\/span><\/p>\n

        Specify start point of arc: @4,0<\/strong><\/p>\n

        (Enter the start point. Here the trick is to give AutoCad the start point and the radius of the arc at the same time)<\/em><\/span><\/p>\n

        Specify end point of arc or [Angle\/chord Length]: A<\/strong><\/p>\n

        Specify included angle: 90<\/strong><\/p>\n

        (Enter the angle of the arc. In this case, it is 90 degrees.)<\/em><\/span><\/p>\n

        Command:<\/p>\n

        \"\"
        Figure Step 5<\/figcaption><\/figure>\n
        USER TIP: <\/strong>Arcs can be drawn in either counterclockwise or clockwise direction by holding down the CTRL key, while in the ARC command, to reverse the direction.<\/div>\n

        Step 6<\/h2>\n

        Enter the CIRCLE command, as shown below, to draw the four circles to complete the drawing. (Figure Step 6A and 6B)<\/p>\n

        Command: CIRCLE<\/strong><\/p>\n

        Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: 3.5,6<\/strong><\/p>\n

        (Since this is the first circle, enter an absolute coordinate for the center point.)<\/em><\/span><\/p>\n

        Specify radius of circle or [Diameter]: D<\/strong><\/p>\n

        (Circles are usually dimensioned with diameters rather then a radius, enter D)<\/em><\/span><\/p>\n

        Specify diameter of circle: 0.65<\/strong><\/p>\n

        Command: CIRCLE<\/strong><\/p>\n

        (Press Enter or Space bar as that will repeat the last command.)<\/em><\/span><\/p>\n

        Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @1,0<\/strong><\/p>\n

        (Notice here, since AutoCAD always remembers the lastpoint, use an @. The lastpoint was the center of the first circle placed.)<\/em><\/span><\/p>\n

        Specify radius of circle or [Diameter] <0.3250>: D<\/strong><\/p>\n

        Specify diameter of circle <0.6500>: 0.75<\/strong><\/p>\n

        Command: CIRCLE <\/strong>(Press Enter or Space bar as that will repeat the last command.<\/p>\n

        Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @0,1.5<\/strong><\/p>\n

        (Use an @ from the center of the last circle drawn.) <\/em><\/span><\/p>\n

        Specify radius of circle or [Diameter] <0.3750>: D <\/strong><\/p>\n

        Specify diameter of circle <0.7500>: 1<\/strong><\/p>\n

        Command: CIRCLE<\/strong><\/p>\n

        (Press Enter or Space bar. That will repeat the last command and save you entering it again.)<\/em><\/span><\/p>\n

        Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @-1,0<\/strong><\/p>\n

        Specify radius of circle or [Diameter] <0.5000>: D <\/strong><\/p>\n

        Specify diameter of circle <1.0000>: 0.5 <\/strong><\/p>\n

        Command:<\/p>\n

        \"\"
        Figure Step 6A<\/figcaption><\/figure>\n
        \"\"
        Figure Step 6B<\/figcaption><\/figure>\n

        Step 7<\/h2>\n

        Save and close the drawing.<\/p>\n

        WORKALONG: Drawing Circles Using the TTR Option<\/h1>\n

        Step 1<\/h2>\n

        Start a new drawing using the template: 2D English<\/span>.<\/p>\n

        Step 2<\/h2>\n

        Save and name the drawing: AutoCAD 2D Workalong 07-2<\/span>.<\/p>\n

        Step 3<\/h2>\n

        Create layer: Object<\/span>, color red. Set it as the current layer. (Figure Step 3)<\/p>\n

        \"\"
        Figure Step 3<\/figcaption><\/figure>\n

        Step 4<\/h2>\n

        Using the dimensioned drawing as a guide and what you already learned, use the LINE command to draw the four outside lines. (Figure Step 4A and 4B)<\/p>\n

        \"\"
        Figure Step 4A<\/figcaption><\/figure>\n
        \"\"
        Figure Step 4B<\/figcaption><\/figure>\n

        Step 5<\/h2>\n

        Enter the CIRCLE command and the TTR option, as shown below, to insert the 2 inch diameter circle. (Figure Step 5A and 5B)<\/p>\n

        Command: CIRCLE<\/strong><\/p>\n

        Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: TTR<\/strong><\/p>\n

        Specify point on object for first tangent of circle: P1<\/strong><\/p>\n

        (Using the graphic cursor, move it on the top horizontal line. When the tangent snap icon appears, press the left mouse button.)<\/em><\/span><\/p>\n

        Specify point on object for second tangent of circle: P2<\/strong><\/p>\n

        (Move the cursor on the vertical line. When the tangent icon appears, pick it.)<\/em><\/span><\/p>\n

        Specify radius of circle <0.7000>: 1<\/strong><\/p>\n

        (Enter the radius of the circle. Be careful, since circles are usually dimensioned in diameters you will have to divide it in half.)<\/em><\/span><\/p>\n

        Command:<\/p>\n

        \"\"
        Figure Step 5A<\/figcaption><\/figure>\n
        \"\"
        Figure Step 5B<\/figcaption><\/figure>\n
        \n

        AUTHOR’S COMMENTS: <\/strong>TTR means ‘ Tangent Tangent Radius ‘. Do not enter the P1 or P2 on the keyboard. They simply mean Pick 1 and Pick 2. To pick, move the Graphic cursor to the desired location, wait for the tangent Autosnap marker to display and when it dose, press the left mouse button.<\/p>\n<\/div>\n

        Step 6<\/h2>\n

        Enter the CIRCLE command and the TTR option, as shown below, to insert the 2.5 inch diameter circle. (Figure Step 6A and 6B)<\/p>\n

        Command: CIRCLE<\/strong><\/p>\n

        Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: TTR<\/strong><\/p>\n

        Specify point on object for first tangent of circle: P3 <\/strong>Specify point on object for second tangent of circle: P4 <\/strong>Specify radius of circle <1.0000>: 1.25<\/strong><\/p>\n

        Command:<\/p>\n

        \"\"
        Figure Step 6A<\/figcaption><\/figure>\n
        \"\"
        Figure Step 6B<\/figcaption><\/figure>\n
        AUTHOR’S COMMENTS: <\/strong>Keep in mind that you do not enter the P3 or P4 on the keyboard. They simply mean Pick 3 and Pick 4 of this workalong.<\/div>\n

        Step 7<\/h2>\n

        Enter the CIRCLE command and the TTR option, as shown below, to insert the middle 2 diameter circle. (Figure Step 7A and 7B)<\/p>\n

        Command: CIRCLE<\/strong><\/p>\n

        Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: TTR<\/strong><\/p>\n

        Specify point on object for first tangent of circle: P5 <\/strong><\/p>\n

        Specify point on object for second tangent of circle: P6 <\/strong><\/p>\n

        Specify radius of circle <1.2500>: 1<\/strong><\/p>\n

        Command:<\/p>\n

        \"\"
        Figure Step 7A<\/figcaption><\/figure>\n
        \"\"
        Figure Step 7B<\/figcaption><\/figure>\n

        Step 8<\/h2>\n

        Save and close the drawing.<\/p>\n

        \n

        MUST KNOW:<\/strong> A very useful feature in AutoCAD is being able to undo a command or redo an undo. All of the commands in the current drawing session can be undone, one at a time. The last undo only can be reversed with a redo.To undo the last command, enter the U command, press CTRL+Z, or click the icon as shown in the figure on the right.<\/p>\n

        Command: U<\/strong><\/p>\n

        If more then one U is entered, it will step back one command at time. This is useful if you made an error several commands earlier.<\/p>\n

        Command: U <\/strong><\/p>\n

        Command: U <\/strong><\/p>\n

        Command: U<\/strong><\/p>\n

        \"\"<\/p>\n

        Enter the REDO command, press CTRL+Y, or click the icon as shown in the figure on the right to redo the undo. The redo will undo the last undo only.<\/p>\n

        Command: REDO<\/strong><\/p>\n

        \"\"<\/p>\n<\/div>\n

        Drafting Lesson: Reading Dimensions for Circles and Arcs<\/h1>\n

        Circles and arcs are dimensioned as follows:<\/p>\n

        Circles are dimensioned with their diameter. For example: 2.0 DIA.<\/p>\n

        Arcs are dimensioned with their radius.<\/p>\n

        For example: 1.5 R<\/p>\n

        When there is more than one circle of the same diameter, it is only dimensioned once. For example: 0.5 DIA., 4 PLACES<\/p>\n

        Sometimes multiple arcs are dimensioned as typical<\/span> <\/em>(TYP.). For example: 2.0 R TYP. Typical simply means that there is at least one more arc of the same size. See Figure 7-8<\/p>\n

        \"\"
        Figure 7-8 Reading Dimensions<\/figcaption><\/figure>\n

        Key Principles<\/h1>\n
        \n
        \n

        Key Principles in Module 7<\/p>\n<\/header>\n

        \n
          \n
        1. A circle is 360 degrees and can be divided into four quadrants.<\/li>\n
        2. All points on a circle are at a given distance from is center point.<\/li>\n
        3. An arc is defined as an open curve in which all points are the same distance from its center point.<\/li>\n
        4. By default, AutoCAD draws arcs counterclockwise.<\/li>\n
        5. When drawing arcs it is best to specify the center point first, the start point that sets the radius second, and an angle to locate the endpoint third.<\/li>\n
        6. A very useful feature in AutoCAD is being able to undo a command or redo an undo.<\/li>\n<\/ol>\n<\/div>\n<\/div>\n

          Lab Exercise 7-1<\/h1>\n

          Time allowed: 40 minutes.<\/p>\n\n\n\n\n
          Drawing Name<\/th>\nTemplate<\/th>\nUnits<\/th>\n<\/tr>\n
          AutoCAD 2D Lab 07-1<\/td>\n2D English<\/td>\nInches<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n\n
          Layering Scheme<\/span><\/caption>\n
          Layer Name<\/th>\nObjects on Layer<\/th>\nColor<\/th>\n<\/tr>\n
          Object<\/td>\nAll lines, circles and arcs<\/td>\nRed<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

          Step 1<\/h2>\n

          Start a new drawing using the template shown above.<\/p>\n

          Step 2<\/h2>\n

          Save and name the drawing with the name shown above.<\/p>\n

          Step 3<\/h2>\n

          Setup the layers using the Layering Scheme shown above.<\/p>\n

          Step 4<\/h2>\n

          Draw the object shown in the figure. In this drawing, all objects should be on layer: Object<\/span> and display red. (Figure Step 4A and 4B)<\/p>\n

          \"\"
          Figure Step 4A
          Completed Drawing<\/figcaption><\/figure>\n
          \"\"
          Figure Step 4B<\/figcaption><\/figure>\n

          Step 5<\/h2>\n

          Enter the UNITS command. In the Units dialogue box, set the Insertion Units to Inches.<\/p>\n

          Step 6<\/h2>\n

          Check the drawing’s accuracy with the key.<\/p>\n

          Step 7<\/h2>\n

          If there are any errors, turn layer: Key off and correct the drawing. If necessary, start a new drawing and draw it again.<\/p>\n

          Step 8<\/h2>\n

          Turn layer Key on. If the drawing still inaccurate, go back to Step 7.<\/p>\n

          Step 9<\/h2>\n

          Turn layer Key off.<\/p>\n

          Step 10<\/h2>\n

          Save and close the drawing.<\/p>\n

          \n

          AUTHOR’S CONSTRUCTION TECHNIQUES: <\/strong>The following steps are the construction technique suggested by the author to help you learn how to construct objects using AutoCAD. It is only the suggested method and if you can complete the drawing accurately using a different construction technique, that is what is important. You may want to compare your construction technique with the authors.<\/p>\n<\/div>\n

          \"\"<\/p>\n

          \n

          AUTHOR’S CONSTRUCTION HINTS: <\/strong>Do your best to complete the lab exercise drawing without using the following hint. If you get stuck and cannot complete it on your own, use the following hint to help you.<\/p>\n<\/div>\n

          Hint 1<\/h2>\n

          (Figure Hint 1)<\/p>\n

          \"\"
          Figure Hint 1<\/figcaption><\/figure>\n

          Lab Exercise 7-2<\/h1>\n

          Time allowed: 40 minutes.<\/p>\n\n\n\n\n
          Drawing Name<\/th>\nTemplate<\/th>\nUnits<\/th>\n<\/tr>\n
          AutoCAD 2D Lab 07-2<\/td>\n2D Metric<\/td>\nMillimeters<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n\n\n\n\n
          Layering Scheme<\/span><\/caption>\n
          Layer Name<\/th>\nObjects on Layer<\/th>\nColor<\/th>\n<\/tr>\n
          Object<\/td>\nAll lines, circles and arcs<\/td>\nRed<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

          Step 1<\/h2>\n

          Start a new drawing using the template shown above.<\/p>\n

          Step 2<\/h2>\n

          Save and name the drawing with the name shown above.<\/p>\n

          Step 3<\/h2>\n

          Setup the layers using the Layering Scheme shown above.<\/p>\n

          Step 4<\/h2>\n

          Draw the object shown in the figure. In this drawing, all objects should be on layer: Object and display red. (Figure Step 4A and 4B)<\/p>\n

          \"\"
          Figure Step 4A
          Completed Drawing<\/figcaption><\/figure>\n
          \"\"
          Figure Step 4B<\/figcaption><\/figure>\n

          Step 5<\/h2>\n

          Enter the UNITS command. In the Units dialogue box, set the Insertion Units to Millimeters.<\/p>\n

          Step 6<\/h2>\n

          Check the drawing’s accuracy with the key.<\/p>\n

          Step 7<\/h2>\n

          If there are any errors, turn layer Key off and correct the drawing. If necessary, start a new drawing and draw it again.<\/p>\n

          Step 8<\/h2>\n

          Turn layer: Key<\/span> on. If the drawing still inaccurate, go back to Step 7.<\/p>\n

          Step 9<\/h2>\n

          Turn layer: Key<\/span> off.<\/p>\n

          Step 10<\/h2>\n

          Save and close the drawing.<\/p>\n

          \n

          AUTHOR’S CONSTRUCTION TECHNIQUES: <\/strong>The following steps are the construction technique suggested by the author to help you learn how to construct objects using AutoCAD. It is only the suggested method and if you can complete the drawing accurately using a different construction technique, that is what is important. You may want to compare your construction technique with the authors.<\/p>\n<\/div>\n

          \"\"<\/p>\n

          \n

          AUTHOR’S CONSTRUCTION HINTS: <\/strong>Do your best to complete the lab exercise drawing without using the following hints. If you get stuck and cannot complete it on your own, use the following hints to help you.<\/p>\n<\/div>\n

          Hint 1
          \n<\/strong><\/h2>\n

          Draw the two circles using the TTR option. (Figure Hint 1)<\/p>\n

          \"\"
          Figure Hint 1<\/figcaption><\/figure>\n

          Hint 2<\/h2>\n

          Draw the four smaller circles using the @ as shown below. (Figure Hint 2)<\/p>\n

          \"\"
          Figure Hint 2<\/figcaption><\/figure>\n

          Command: C<\/strong><\/p>\n

          CIRCLE Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: 85,170<\/strong><\/p>\n

          Specify radius of circle or [Diameter]: D <\/strong><\/p>\n

          Specify diameter of circle: 10 <\/strong><\/p>\n

          Command: C<\/strong><\/p>\n

          CIRCLE Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @40,0<\/strong><\/p>\n

          Specify radius of circle or [Diameter] <5.0000>:<\/p>\n

          Command: C<\/strong><\/p>\n

          CIRCLE Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @0,20<\/strong><\/p>\n

          Specify radius of circle or [Diameter] <5.0000>:<\/p>\n

          Command: C<\/strong><\/p>\n

          CIRCLE Specify center point for circle or [3P\/2P\/Ttr (tan tan radius)]: @-40,0<\/strong><\/p>\n

          Specify radius of circle or [Diameter] <5.0000>:<\/p>\n

          Command:<\/p>\n","protected":false},"author":90,"menu_order":7,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-348","chapter","type-chapter","status-publish","hentry"],"part":307,"_links":{"self":[{"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/pressbooks\/v2\/chapters\/348","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/wp\/v2\/users\/90"}],"version-history":[{"count":1,"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/pressbooks\/v2\/chapters\/348\/revisions"}],"predecessor-version":[{"id":349,"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/pressbooks\/v2\/chapters\/348\/revisions\/349"}],"part":[{"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/pressbooks\/v2\/parts\/307"}],"metadata":[{"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/pressbooks\/v2\/chapters\/348\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/wp\/v2\/media?parent=348"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/pressbooks\/v2\/chapter-type?post=348"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/wp\/v2\/contributor?post=348"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/opentextbc.ca\/autocad2d\/wp-json\/wp\/v2\/license?post=348"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}