Beginning AutoCAD 2002 Episode 3 pps

Centre-radius Select the CIRCLE icon from the Draw toolbar and: prompt Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: enter 75,75 <R> – the circle centre point prompt Specify radius of circle or [Diameter] enter 20 <R> – the circle radius. Centre-Diameter From the menu bar select Draw-Circle-Center,Diameter and: prompt Specify center point for circle or enter 175,75 <R> prompt Specify diameter of circle enter 20 <R> Two points on circle diameter At the command line enter CIRCLE <R> and: prompt Specify center point for circle or enter 2P <R> – the two point option prompt Specify first end point on circle’s diameter enter 280,210 <R> prompt Specify second end point on circle’s diameter enter 330,260 <R> Three points on circle circumference Menu bar selection with Draw-Circle-3 Points and: prompt Specify first point on circle respond pick any point within the top left square prompt Specify second point on circle respond pick another point within the top left square prompt Specify third point on circle respond drag out the circle and pick a point. Circle creation 53 Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 53 TTR: tangent-tangent-radius a) Menu bar with Draw-Circle-Tan,Tan,Radius and: prompt Specify point on object for first tangent of circle respond move cursor on to line A and leave for a second and 1. a small marker is displayed 2. Deferred Tangent tooltip displayed respond pick line A, i.e. left click on it prompt Specify point on object for second tangent of circle respond pick line B prompt Specify radius of circle enter 25 <R> and a circle is drawn as tangent to the two selected lines. b) At the command line enter CIRCLE <R> and: prompt Specify center point for circle or enter TTR <R> – the tan,tan,radius option prompt first tangent point prompt and: pick line C prompt second tangent point prompt and: pick line D prompt radius prompt and enter: 15 <R> and a circle is drawn tangential to the two selected lines, line C being assumed extended. TTT: tangent-tangent-tangent a) Menu bar with Draw-Circle-Tan,Tan,Tan and: prompt Specify first point on circle and: pick line L1 prompt Specify second point on circle and: pick line L2 prompt Specify third point on circle and: pick circle C1. b) Activate the Draw-Circle-Tan,Tan,Tan sequence and: prompt Specify first point on circle and: pick circle C1 prompt Specify second point on circle and: pick circle C2 prompt Specify third point on circle and: pick circle C3. Circles have been drawn tangentially to selected objects, these being: a) two lines and a circle b) three circles. Questions 1 How long would it take to draw a circle as a tangent to three other circles by conventional draughting methods, i.e. drawing board, T square, set squares, etc.? 2 Can a circle be drawn as a tangent to two circles and a line, or to three inclined lines? Saving the drawing Assuming that the CIRCLE commands have been entered correctly, your drawing should resemble Fig. 10.1 (without the text) and is ready to be saved for future work. From the menu bar select File-Save As and: prompt Save Drawing As dialogue box with 1. Begin folder name active 2. File name: DEMODRG respond pick Save prompt Drawing already exists message respond pick Yes – obvious? 54 Beginning AutoCAD 2002 Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 54 Task The two Tan,Tan,Tan circles have been created without anything being known about their radii. 1 From the menu bar select Tools-Inquiry-List and: prompt Select objects respond pick the smaller TTT circle prompt 1. found and Select objects respond right-click prompt AutoCAD Text window with information about the circle. 2 Note the information then cancel the text window by picking the right (X) button from the title bar 3 Repeat the Tools-Inquiry-List sequence for the larger TTT circle 4 The information for my two TTT circles is as follows: smaller larger Centre point 139.52, 208.53 131.88, 122.06 Radius 16.47 53.83 Circumference 103.51 338.21 Area 852.67 9102.42 5 Could you calculate these figures manually as easily as has been demonstrated? Assignment 1 Open your A:STDA3 standard sheet. 2 Refer to the Activity 3 drawing which can be completed with only the LINE and CIRCLE commands. 3 The method of completing the drawings is at your discretion. 4 Remember that absolute coordinates are recommended for circle centres and that the TTR method is very useful. 5 You may require some ‘sums’ for certain circle centres, but the figures are relatively simple. 6 When the drawing is complete, save it as C:\BEGIN\ACT3. Summary 1 Circles can be created by six methods, the user specifying: a) a centre point and radius b) a centre point and diameter c) two points on the circle diameter d) any three points on the circle circumference e) two tangent specification points and the circle radius f) three tangent specification points. 2 The TTR and TTT options can be used with lines, circles, arcs and other objects. 3 The centre point and radius can be specified by: a) coordinate entry b) picking a point on the screen c) referencing existing entities – next chapter. Circle creation 55 Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 55 Object snap The lines and circles drawn so far have been created by coordinate input. While this is the basic method of creating objects, it is often desirable to ‘reference’ existing objects already displayed on the screen, e.g. we may want to: a) draw a circle with its centre at the midpoint of an existing line b) draw a line, from a circle centre perpendicular to another line. These types of operations are achieved using the object snap modes – generally referred to as OSNAP – and are one of the most useful (and powerful) draughting aids. Object snap modes are used transparently, i.e. whilst in a command, and can be activated: a) from the Object Snap toolbar b) by direct keyboard entry. While the toolbar method is the quicker and easier to use, we will investigate both methods. Getting ready 1 Open your C:\BEGIN\DEMODRG of the squares and circles. 2 Erase the two TTT circles and the lower right square. 3 Display the Draw, Modify and Object Snap toolbars and position them to suit. 4 Refer to Fig. 11.1. Chapter 11 Figure 11.1 Using the object snap modes with C:\BEGIN\DEMODRG. Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 56 Using object snap from the keyboard Activate the LINE command and: prompt Specify first point enter MID <R> prompt of respond 1. move cursor to line D1 and leave for few seconds 2. coloured triangular marker at line midpoint 3. Midpoint tooltip displayed in colour now pick line D1, i.e. left-click and line ‘snaps to’ the midpoint of D1 prompt Specify next point enter PERP <R> prompt to respond pick line D2 – note coloured Perpendicular marker prompt Specify next point enter CEN <R> prompt of respond pick circle D3 – note coloured Center marker prompt Specify next point enter INT <R> prompt of respond pick point D4 – note blue Intersection marker prompt Specify next point respond right-click and pick Enter to end the line sequence. Using object snap from the toolbar Activate the LINE command and: prompt Specify first point respond pick the Snap to Nearest icon prompt nea to respond pick any point on line K1 prompt Specify next point respond pick the Snap to Apparent Intersection icon prompt appint of respond pick line K2 prompt and respond pick line K3 prompt Specify next point respond pick the Snap to Perpendicular icon prompt per to respond pick line K4 prompt Specify next point respond pick the Snap to Tangent icon prompt tan to respond pick circle K5 prompt Specify next point respond pick the Snap to Midpoint icon prompt mid of respond pick line K6 prompt Specify next point respond pick the Snap to Quadrant icon prompt qua of respond pick circle K7 prompt Specify next point respond pick the Snap to Endpoint icon prompt endp of respond pick line K8 prompt Specify next point respond right-click and pick Enter to end the line sequence. Object snap 57 Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 57 Object snap with circles Select the CIRCLE icon from the Draw toolbar and: prompt Specify center point for circle or respond pick the Snap to Midpoint icon prompt mid of respond pick line P1 prompt Specify radius of circle or respond pick the Snap to Center icon prompt cen of respond pick circle P2. Note 1 Save your drawing at this stage as C:\BEGIN\DEMODRG. 2 The endpoint ‘snapped to’ depends on which part of the line is ‘picked’. The coloured marker indicates which line endpoint. 3 A circle has four quadrants, these being at the 3, 12, 9, 6 o’clock positions. The coloured marker indicates which quadrant will be snapped to. The extension and parallel object snap modes The object snap modes selected so far should have been self-explanatory to the user, i.e. endpoint will snap to the end of a line, center will snap to the centre of a circle, etc. The extension and parallel modes are used as follows: a) Extension: used with lines and arcs and gives a temporary extension line as the cursor is passed over the endpoint of an object b) Parallel: used with straight line objects only and allows a vector to be drawn parallel to another object. 58 Beginning AutoCAD 2002 Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 58 To demonstrate these two object snap modes: 1 Continue with the DEMODRG and turn on the grid and snap. Set the spacing to 10 for both. 2 Activate the LINE command and: prompt Specify first point respond pick the Snap to Extension icon prompt ext of respond move cursor over point W1 then drag to right and 1. highlighted extension line dragged out 2. information displayed about distance from endpoint as a tooltip respond 1. move cursor until Extension: 50.00<0.0 displayed 2. left-click prompt Specify next point respond pick the Snap to Extension icon prompt ext of respond 1. move cursor over point W2 2. move cursor vertically up until Extension:40.00<90.0 is displayed 3. left-click prompt Specify next point respond pick the Snap to Parallel icon prompt par to respond 1. move cursor over line W3, leave for a few seconds and note the display 2. move cursor to right of last pick point and: a) highlighted line b) information about distance and angle displayed 3. move cursor to right until 70.00<0.0 displayed 4. left-click prompt Specify next point respond pick the Snap to Parallel icon prompt par to respond 1. move cursor over line W4 2. move cursor vertically below last pick point 3. move cursor until 140.00<270.0 displayed 4. left-click prompt Specify next point enter C <R> to close the shape and end the line command 3 The line segments should be as Fig. 11.1 4 Save your layout as C:\BEGIN\DEMODRG, updating the existing DEMODRG. Running object snap Using the object snap icons from the toolbar will increase the speed of the draughting process, but it can still be ‘tedious’ to have to pick the icon every time an ENDpoint (for example) is required. It is possible to ‘preset’ the object snap mode to ENDpoint, MIDpoint, CENter, etc., and this is called a running object snap. Pre-setting the object snap does not preclude the user from selecting another mode, i.e. if you have set an ENDpoint running object snap, you can still pick the INTersection icon. The running object snap can be set: 1 From the menu bar with Tools-Drafting Settings and pick the Object Snap tab 2 Entering OSNAP <R> at the command line 3 Picking the Object Snap Settings icon from the Object Snap toolbar 4 With a right-click on OSNAP in the Status bar and picking Settings Each method displays the Drafting Settings dialogue box with the Object Snap tab active. Object snap 59 Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 59 Task 1 Select Tools-Drafting Settings from the menu bar and: prompt Drafting Settings dialogue box respond 1. ensure the Object Snap tab is active 2. ensure Object Snap On (F3) is active 3. activate Endpoint, Midpoint and Nearest by picking the appropriate box – tick means active 4. dialogue box as Fig. 11.2 5. pick OK. 2 Now activate the LINE command and move the cursor cross-hairs onto any line and leave it. 3 A coloured marker will be displayed at the Nearest point of the line – it may be that you have the midpoint marker displayed. 4 Press the TAB key to cycle through the set running object snaps, i.e. the line should display the cross, square and triangular coloured markers for the Nearest, Endpoint and Midpoint object snap settings. 5 Cancel the line command with ESC. 60 Beginning AutoCAD 2002 Figure 11.2 The Drafting Settings dialogue box with the Object Snap tab active. Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 60 AutoSnap and AutoTrack The Object Snap dialogue box allows the user to select Options which displays the Drafting tab dialogue box – Fig. 11.3. With this dialogue box, the user can control both the AutoSnap and the AutoTrack settings which can be simply defined as: a) AutoSnap: a visual aid for the user to see and use object snaps efficiently, i.e. a marker and tooltip displayed. b) AutoTrack: an aid to the user to assist with drawing at specific angles, i.e. polar tracking. The settings which can be altered with AutoSnap and AutoTrack are: AutoSnap AutoTrack Marker Display polar tracking vector Magnet Display full screen tracking vector Display tool tip Display autotrack tooltip Display aperture box Alter alignment point acquisition Alter marker colour Alter aperture size Alter marker size. The various terms should be self-explanatory at this stage(?): a) Marker: is the geometric shape displayed at a snap point. b) Magnet: locks the aperture box onto the snap point. c) Tool tip: is a flag describing the name of the snap location. The rest of the options should be apparent. It is normal to have the marker, magnet and tool tip active (ticked). The colour of the marker and the aperture box sizes are at the user’s discretion, as is having polar tracking ‘on’. Object snap 61 Figure 11.3 The Drafting tab of the Options dialogue box. Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 61 Cancelling a running object snap A running object snap can be left ‘active’ once it has been set, but this can cause problems if the user ‘forgets’ about it. The running snap can be cancelled: 1 From the Object Settings dialogue box with Clear All. 2 By entering –OSNAP <R> at the command line and: prompt Enter list of object snap modes enter NONE <R> 3 Note: a) Selecting the Snap to None icon from the Object Snap toolbar will turn off the object snap running modes for the next point selected. b) Using the Object Snap dialogue box is the recommended way of activating and de-activating object snaps. The Snap From object snap This is a very useful object snap, allowing the user the reference points relative to existing objects. 1 Using the squares and circles which should still be displayed, erase the lines and circle created with the object snaps. This is to give ‘some space’. Ensure the Object Snap toolbar is displayed. 2 Activate the circle command and: prompt Specify center point for circle respond pick Snap From icon from the Object Snap toolbar prompt from Base Point respond pick Snap to Midpoint icon prompt mid of respond pick line K8 prompt <Offset> enter @50,0 <R> prompt Specify radius of circle enter 20 <R> 3 A circle is drawn with its centre 50mm horizontally from the midpoint of the selected line 4 Select the LINE icon and: prompt Specify first point respond pick Snap From icon prompt from Base point respond pick Intersection icon prompt int of respond pick point W1 prompt <Offset> enter @25,25 <R> prompt Specify next point respond pick Snap From icon prompt from Base point respond pick Snap to Centre icon prompt cen of respond pick circle K7 prompt <Offset> enter @80<–20 <R> prompt Specify next point respond right-click and Enter. 5 A line is drawn between the specified points. The endpoints of this line have been ‘offset’ from the selected objects by the entered coordinate values. 6 Do not save these additions to your drawing layout. 62 Beginning AutoCAD 2002 Beginning with AutoCAD 2002.qxd 14/06/2002 19:04 Page 62 [...]... been turned off Figure 13. 3 Layer Message dialogue box 7 Re-activate the Layer Properties Manager dialogue box and: a) pick the 0 layer name – highlighted in colour b) pick the ‘blue light’ and it changes to yellow (ON) c) pick OK 8 The line and circle objects displayed – layer 0 is on 73 Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 74 74 Beginning AutoCAD 2002 Linetypes AutoCAD allows the user... remaining layers Figure 13. 1 demonstrates the layer concept with: a) Five layers used to create a simple component Each ‘part’ of the component has been created on ‘its own’ layer b) The layers ‘laid on top of each other’ The effect is that the user ‘sees’ one component Figure 13. 1 Layer concept Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 72 72 Beginning AutoCAD 2002 The following points... exercise Figure 13. 7 The Save Layer States dialogue box 81 Beginning with AutoCAD 2002. qxd 14/06 /2002 19:05 Page 82 82 Beginning AutoCAD 2002 Make Object’s Layer Current icon Layers icon Layers Previous icon Layer control Figure 13. 8 Colour control Linetype control Lineweight control The Object Properties toolbar information for C:\BEGIN\A3PAPER The Object Properties toolbar The Object Properties toolbar... bar Draw-Arc-Continue and: prompt End point, and cursor snaps to end point of the last arc drawn enter @50,0 3 Repeat the Arc-Continue selection and: prompt End point respond snap to Center of circle K2 67 Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 68 68 Beginning AutoCAD 2002 Donut A donut (doughnut) is a ‘solid filled’ circle or annulus (a washer shape), the user specifying the inside... Manager dialogue box Figure 13. 4 Load or Reload Linetypes dialogue box Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 75 Layers and standard sheet 2 Figure 13. 5 Select Linetype dialogue box 2 The drawing screen will display the three objects and the border with center linetype appearance Remember that AutoCAD is an American package – hence center, and not centre 3 Note Although we have used... line displays Color: red square Red d) pick OK 3 The screen displays the objects with red centre lines 4 Note the Object Properties toolbar which displays: a) layer 0 with a red square b) the ByLayer colour is a red square c) the ByLayer linetype has a center linetype appearance 75 Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 76 76 Beginning AutoCAD 2002 Task By selecting the Layers icon from... (f) Figure 11.4 Using Object Snap Tracking to draw line segments Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 64 64 Beginning AutoCAD 2002 5 Task 1 a) from the Object Snap Settings, deactivate the Endpoint and Center snap modes and activate the Midpoint snap mode b) from the Polar Tracking Settings, set the incremental angle to 30 c) activate the circle command and acquire the midpoint of the... methods 2 Partial ellipses (arcs) are possible 3 The created ellipses are ‘true’, i.e have a centre point Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 71 Chapter 13 Layers and standard sheet 2 All the objects that have been drawn so far have had a continuous linetype and no attempt has been made to introduce centre or hidden lines, or even colour AutoCAD has a facility called LAYERS which allows... – highlighted 2 Show details active 3 at Details, highlight Layer1 name and enter OUT 4 Layer1 is renamed OUT in the layer list 5 repeat the above steps and rename layer2-layer7 with the following names: layer2: CL layer3: HID layer4: DIMS layer5: TEXT layer6: SECT layer7: CONS Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 77 Layers and standard sheet 2 3 4 b) assigning the linetypes 1 pick... dialogue to save the layers (with linetypes and colours) which have been created Figure 13. 6 The Layer Properties Manager dialogue box with colours and linetypes set 77 Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 78 78 Beginning AutoCAD 2002 The current layer The current layer is the one on which all objects are drawn The current layer name appears in the Layer Properties Manager section of the Object . two TTT circles is as follows: smaller larger Centre point 139 .52, 208. 53 131 .88, 122.06 Radius 16.47 53. 83 Circumference 1 03. 51 33 8.21 Area 852.67 9102.42 5 Could you calculate these figures. Save prompt Drawing already exists message respond pick Yes – obvious? 54 Beginning AutoCAD 2002 Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 54 Task The two Tan,Tan,Tan circles have been created. only and allows a vector to be drawn parallel to another object. 58 Beginning AutoCAD 2002 Beginning with AutoCAD 2002. qxd 14/06 /2002 19:04 Page 58 To demonstrate these two object snap modes: 1