CAD Application Tips (II)

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CAD Application Tips (II) Thursday, April 22, 2010 10:10 43. How to set line width? 　　There are many ways to change the line width of AutoCAD objects. Yun’s common approach is to use the color of the entities on the graphical screen to obtain different line widths for the output lines. In other words, when drawing, different types of shapes are colored differently according to one’s needs. Then set different line widths and colors for the printed output. The method is as follows: Click the “File” menu and select “Print”, or press “Ctrl+P”; a dialog box titled “Print/Plot Configuration” will then appear. In \"Pen Parameters\", click \"Pen Assignment\". The “Pen Assignment” dialog box appears, where you can specify the pen number for each color code and choose an appropriate pen width. First, let me explain to you how the pen width is determined. The pen width is primarily determined by the resolution of the printing device and the distance between the print dots, as given by the formula /. AutoCAD will use these standard values to replace the values we enter arbitrarily. 　　Below are the smallest pen widths for several common printers: the HP Laserjet III printer series uses 1/300, the Canon BubbleJet inkjet printer series uses 1/360, the HP LaserJet IV printer series uses 1/600, and the new Canon BubbleJet inkjet printers use 1/720. Understanding this, we can then enter the desired line width value in the “Pen Assignment” dialog box. For example, color number one is denoted as “1/300”, color number two as “2/300”, and so on. The system will automatically calculate similar small values. 44. Regarding the issue of line width. 　　LineWeight represents an absolute line width, whereas the width of a polyline is relative. In other words, the LineWeight remains unchanged regardless of the size at which the graphic is printed, while the width of a polyline changes depending on the printing scale. No matter how much a solid is scaled, its LineWeight stays the same, but the width of the polyline changes with the scaling factor. 45. The clever use of keys in AutoCAD’s snap function. 　　When it is necessary to capture a point on an object, simply bring the mouse close to that object, and keep pressing the TAb key. Then, certain specific points on that object (such as the endpoints of lines, midpoint, perpendicular points, intersection points with the object, the points at the quarters of a circle, the center point, tangent points, perpendicular points, and intersection points) will be displayed in turn. Click with the left button on the desired point to capture it. Note that when the mouse is brought near the intersection point of two objects, their special points will be displayed in turn (the object to which they belong will turn into a dashed line), which is very useful for locating points in areas where the geometry is relatively complex. 　　 46. Is the ellipse generated by the ellipse command a polyline or a solid? 　　It is determined by the system variable PELLIPSE; when it is 1, the ellipse generated is a multivalued line. 　　 47. Some common shortcut keys. 　　F1: Get help. F2: Switch between the drawing window and the text window. F3: Control whether automatic object snapping is enabled. F4: Control of the digitizer. F5: Switch between isometric planes. F6: Control the way coordinates are displayed on the status bar. F7: Control of the grid display mode. F8: Control of the orthographic mode. F9: Control of the grid snapping mode. F10: Control of the polar mode. F11: Object tracking control. Ctrl+B: Control of the grid snapping mode (F9). Ctrl+C: Copy the selected objects to the clipboard. Ctrl+F: Control whether automatic object snapping is enabled (F3). Ctrl+G: Control of the grid display mode (F7). Ctrl+J: Repeat the previous command. Ctrl+K: Create a hyperlink. Ctrl+N: Create a new graphic file. Ctrl+M: Open the options dialog box. Ctrl+1: Open the properties dialog box. Ctrl+2: Open the image resource manager. Ctrl+6: Open the image data atoms. Ctrl+: Open an image file. Ctrl+P: Open the print dialog box. Ctrl+S: Save the file. Ctrl+U: Control of the polar mode (F10). Ctrl+V: Paste the content from the clipboard. Ctrl+W: Object tracking control (F11). Ctrl+X: Cut the selected content. Ctrl+Y: Redo. Ctrl+Z: Undo the previous action. 48. Model space and paper space. 　　AutoCAD has two different spaces: Model Space and Paper Space (using the LAYOUT tab). 　　Features of viewports in model space: (1) In model space, it is possible to draw two-dimensional graphics and three-dimensional models at full scale, along with dimension annotations. (2) In model space, each viewport contains a view of an object. For example: setting different viewports will yield top views, front views, side views, and 3D views, etc. (3) Use the VPORTS command to create viewports and set their parameters, which can be saved for later use. (4) Viewports are tiled; they cannot overlap and are always adjacent to each other. (5) At any given moment, only one viewport is active; the crosshair can appear in only one viewport, and only that active viewport can be edited (translated, scaled, etc.). (6) Only active viewports can be printed ； If the UCS icon is set to ON, it will appear in each viewport. (7) The system variable MAXACTVP determines that the viewport range is from 2 to 64. 　　Features of the viewport in paper space: (1) PAPER replaces MODEL on the status bar. (2) The VPORTS, PS, MS, and VPLAYER commands are active. (The PLAN, VPOINT, and DVIEW commands can be used only after the MS command is activated.) (3) The boundaries of the viewport are entities. You can delete, move, scale, and stretch the viewport. (4) There are no restrictions on the shape of the viewport. For example: circular viewports, polygonal viewports, etc., can be created. (5) Viewports are not tiled; they can be overlapped or separated using various methods. (6) Each viewport is on the layer that created it; the viewport boundaries have the same color as the layer, but the boundary style is always a solid line. When exporting the image, if you do not want to print the viewport, you can place it on a separate layer and freeze it. (7) Multiple viewports can be printed simultaneously. (8) The crosshair can extend continuously, passing through the entire graphics screen, independent of each viewport. (9) Viewports can be opened or closed using the MVIEW command; the SOLVIEW command is used to create viewports, while the VPORTS command is used to restore viewports saved in model space. By default, viewports are active once they are created. Closing some viewports can increase the redraw speed. (10) When printing a graphic and it is necessary to hide the hidden lines of the 3D graphic, you can use the MVIEW command > HIDEPLOT to select the viewport boundaries that are to be hidden. (11) The system variable MAXACTVP determines that the number of viewports in active state is 64. Through the explanations above, I believe everyone now has a clear understanding of these two spaces. However, keep in mind that when we first enter the drawing space, we cannot see any viewports; we must use the VPORTS or MVIEW commands to create new viewports or restore the existing viewport settings (which are usually saved in model space). The MS and PS commands can be used to switch back and forth between model space and LAYOUT (paper space). 　　 49. How to draw curves? 　　When drawing patterns, it is common to encounter problems such as drawing intersection lines, intersection curves, and other types of curves. Manual drawing is troublesome; it requires finding special points and a certain number of ordinary points, and the curves drawn can have large errors. It is easy to draw planar curves or spatial curves using AutoCAD 2000. ---- Method 1: Use the Pline command to draw a polyline on a 2D graph that passes through specific points; by fitting it with a Fit or Spline curve using the Pedit command, it can be transformed into a smooth planar curve. Using the 3Dpoly command to draw polyline paths on 3D shapes, and then fitting them with spline curves via the Pedit command, smooth spatial curves can be created. ---- Method 2: Use the Solids command to create basic 3D solids (cubes, cylinders, cones, spheres, etc.), and then apply Boolean combination operations such as intersection, union, difference, and interference to obtain various complex solids. After that, use the View/3D Viewpoint dropdown menu to select different viewpoints in order to generate standard views and obtain various projections of the curve. 　　 50. What scale is good for drawing in AutoCAD? 　　It’s convenient to draw at a 1:1 ratio for Yun; the output ratio can be adjusted as desired. Drawing scale and output scale are two different concepts. When exporting, if \"1 unit of output = 500 units in drawing\", it means the output is done at a scale of 1/500; if \"10 units of output = 1 unit in drawing\", it means the output is enlarged by a factor of 10. There are many advantages to drawing at a 1:1 ratio. First, errors are easy to detect, as drawing based on actual dimensions makes it simple to identify any unreasonable settings regarding the sizes. Secondly, marking dimensions is very convenient; the software measures the values itself, and if a mistake is made in drawing, it can be detected by looking at the dimension values (of course, the software also allows setting the dimension scaling, but it still requires extra effort). Third, when copying partial graphics between different drawings or using blocks, since the scale is 1:1, it is easy to adjust the block size. Fourth, it is very convenient for assembling drawings from part drawings or for breaking down assembly drawings into part drawings. Fifth, there is no need for complicated calculations of scaling up or down, which improves work efficiency and prevents errors that may occur during the conversion process. 　　 51. How to use custom patterns for filling in AutoCAD? 　　All fill patterns in AutoCAD are saved in a library file named acad.pat, whose default path is the \\Acad2000\\Support directory within the installation folder. We can directly edit this file using a text editor, adding statements for custom patterns ； You can also create your own *.Pat file and save it in the same directory; CAD can recognize it. 　　Next, we will use the example of creating a new pattern library file for diamond-patterned steel plates to illustrate how to customize patterns in AutoCAD 2000. 　 First, create a diamond pattern in CAD in accordance with national standards, and indicate the dimensions of each part. Refer to the standard format of the following library file: *pattern-name angle, x-origin, y-origin, delta-x, delta-y The first line is the title line. Immediately following the asterisk is the pattern name, which is displayed when using the HATCH command to select a pattern. The text within square brackets is an optional description shown when the pattern is displayed using the “?” option of the HATCH command. If the description is omitted, there must be no comma after the pattern name. 　　The second line is the description line for the pattern. There can be one or more lines. Their meanings are as follows: the angle at which a line is drawn; the X and Y coordinates of the point that a line in the set of filled lines passes through; the displacement between two filled lines; the vertical distance between two filled lines. Dash-n is a length parameter for a line, which can take positive or negative values or be zero. A positive value indicates that the corresponding segment is a solid line, a negative value means the segment is left empty, and a value of zero results in a dot being drawn. 　　Okay, we can start editing now. Open Notepad and write the following:
*custom, steel plate GB/T3277-1991
68.4667, 0, 0, -9.8646, 25, 30.0213, -6.59
111.5333, 0, 0, 9.8646, 25, 30.0213, -6.59
68.4667, -11.0191, 27.926, -9.8646, 25, 30.0213, -6.59
111.5333, 11.0191, 27.926, 9.8646, 25, 30.0213, -6.59
The four lines of data in this example correspond to segments a, b, c, and d in Figure 1, respectively. By referring to the illustrations, the values for each item should be easy to understand. Here, we will focus only on the rules governing the values of delta-x and delta-y. For easier understanding, we set up a UCS coordinate system as shown in the diagram, defining the origin and the positive direction of the X-axis. The vertical distance of 25 between segments a and e on the Y-axis constitutes delta-y, which is equivalent to the value 25 used in AutoCAD’s offset command ； If segment e is derived from segment a through an offset, then segment e also moves 9.8646 units in the negative X-direction relative to segment a; this displacement is known as delta-x. 　　Here are a few more things to note: Each line in the pattern definition file can contain up to 80 characters. 　　AutoCAD ignores empty lines and the text to the right of semicolons. According to this rule, we can add copyright information, notes, or any content we wish to include in the file. For example: ;Copyright (c) 2000 by everyone. All rights reserved. Save the file afterward, naming it custom.Pat. Note, the file name must be the same as the pattern name. 　　At this point, I believe everyone has mastered the method of customizing patterns. Now, with just a little patience, you can create very complex patterns. 　　The method for calling the library file is as follows: The filler patterns and files I prepared are provided in the appendix; unzip them and place them in the \\Acad2000\\Support directory. Open AutoCAD and run the Hatch command. In the Boundary Hatch dialog box that appears, select Custom in the Type field. Click on the Swatch tab; this will bring up the Hatch Pattern Palette dialog box. Choose the Custom tab and specify the custom.Pat file we just created. A preview of the filling effect will then appear on the right side – and that is exactly the diamond-patterned steel plate design we need. 　　 52. How to use the trim command to trim multiple line segments at once? For example, line AB intersects four parallel lines; now we want to remove the part on the right side of line AB. Execute the trim command, select AB when prompted to choose an object and press Enter, then enter F and press Enter again. Next, draw a line on the right side of AB and press Enter – that’s it. 　　 53. How to expand the drawing space? 　　1) Increase the system display resolution. 2) Adjust the \"Appearance\" settings in the monitor properties to change the size of icons, scroll bars, title buttons, text, etc. 3) Remove unnecessary elements such as screen menus, scroll bars, and rarely used toolbars. To remove the screen menu and scroll bars, you can make these selections under the \"Drawing Window Parameters\" option on the \"Display\" tab of the \"Preferences\" dialog box (see step 4). 　　4) Set the system taskbar to disappear automatically and minimize the command line as much as possible. 　　5) On the “Settings” page of the display properties, set the desktop size to be one or two levels larger than the screen size, so that you can work in a very large working area. 　　 54. How to print drawings using WORD? 　　In Word, there is a feature for inserting objects, one of which are AutoCAD drawings. Before inserting them, don’t forget to change the background color of the drawings in AutoCAD to white (go to Tools – Options – Display – Colors to make this change); otherwise, the drawings will have a filled color and won’t be visible. 　　 55. The difference between using a “-” before a command and not using it. The meaning of using a “-” versus not using it in AUTOCAD is different; the use of a “-” was introduced in AUTOCAD 2000 as a way to ensure that commands had a consistent format across different language versions. Adding a “-” before the command enables command-line mode for that command; without it, dialog box mode is used. To be more specific: when a “-” is added, no dialog box appears during command execution, and all commands are entered in the command line. Without the “-”, a dialog box appears when the command is run, and parameter entry is done within that dialog box. 56. How to compare two graphs? 　　One of the images can be turned into a block, and its color can be changed to a bright color such as yellow; then the two images can be overlaid on top of each other, and any discrepancies will be easily visible. 　　 57. The width issue of polylines. 　　When the pline line is set to a width other than 0, it will be printed at that width. If the width of this polyline is too small, no width effect will be produced. (If drawing in millimeters and setting the polyline width to 10, when printing at a 1:100 scale, this corresponds to 0.1 millimeters.) ) Therefore, the width setting of polylines must take the printing scale into account. When the width is 0, it can be set according to the object’s properties (just like other objects). 　　 58. Dashed lines are drawn in model space and appear as dashed lines when printed, but why do they turn into solid lines when printed in layout? How to print dashed lines in a layout? 　　It is estimated that the linear scale was changed, and at the same time the \"scale to paper space\" method was used (which is the default method in CAD). In the Linear Settings dialog box, uncheck the box next to “Scale to paper space”. 　　 59. How to combine multiple straight lines into one? 　　This can be done using the Group command. 　　 60. How to merge multiple lines into a polyline? 　　Use the PEDIT command, which has a merge option. 　　 61. When AUTOCAD is forced to close due to an error and then restarted, the following issue occurs: the \"File -- Open\" command does not display a window for selecting files, and the same thing happens when trying to save files. What should be done? 　　The FILEDIA variable should be modified. 　　 62. How to load it automatically after modifying ACAD.LSP? 　　The system variable ACADLSPASDOC can be changed to 1. 　　 63. How to modify the scale of dimension annotations? 　　Method 1: DIMSCALE determines the scale of dimensioning; it is an integer value with a default of 1. It is advisable to change this value to the desired scaling factor when the drawing needs to be scaled to a certain proportion. 　　Method 2: Format -- Dimension Style (select the dimension style to be modified) -- Modify -- Primary Unit -- Scale Factor, and make the changes. 　　 64. How to control entity display? 　　Taking AutoCAD 2000 as an example, three system variables are commonly used for keyboard input to control the display of entities. 　　ISOLINES: By default, solids are displayed in wireframe format, with each surface on the solid represented by grid lines. The number of grid lines is controlled by this system variable, with valid values ranging from 0 to 2047, and the initial value is 4. The higher the grid value, the easier it is to observe the solid, but the waiting time before it appears increases. 　　DISPSILH: This variable controls the display of the entity’s contour edges; its value can be 0 or 1. The default value is 0, which means the contour edges are not displayed. When set to 1, the contour edges are shown. 　　FACETRES: This variable controls the smoothness of the entity after it has been HIDDEN, SHADED, or RENDERED. The valid range is 0.01–10.0, with a default value of 0.5. The higher its value, the smoother the display, but the waiting time before the display appears increases when using the HIDE, SHADE, and RENDER commands. Usually, its value is increased only during the final output. 　　 65. How to use the middle button of the mouse. 　　1. Ctrl+middle mouse button can enable panning similar to other software. 　　2. Double-clicking the middle mouse button is equivalent to ZOOM E. 　　　　 66. Multiple reproductions always require entering M – how can this be simplified? 　　It is possible to add a program to the acad.lsp file so that there is no need to enter “M”. The method is as follows:
(defun C:CVV ()
(setvar “cmdecho” 0)
(setq css (ssget)) (command “copy” css "" “m”)
(setq css nil) (setvar “cmdecho” 1)
(prin1)
)
By simply entering CVV and pressing Enter, multiple copies can be made. 　　 67. The direction issue when interrupting a circle. 　　AUTOCAD will delete the arc on the circle between the first break point and the second break point in a counterclockwise direction. 　　 68. How to quickly draw a tangent semicircle to parallel lines? 　　Using the FILLET command with rounded corners is 10 times faster than drawing tangent circles first and then cutting them. 　　 69. How to quickly enter a distance? 　　Following the prompt at the positioning point, enter a numerical value to position the next point at a specified distance in the direction indicated by the cursor; this function is typically used when the \"Orthogonal\" or \"Snap\" mode is active. For example: Execute command: line ； Specify first point: Specify the point ； Specify the next point: Move the cursor in the desired direction, enter 5, and press Enter. 　　 70. How to restore smoothness to a rough graphic? 　　Sometimes, after scaling or zooming a graphic, it becomes rough – for example, circles turn into polygons – and the regen command can be used to restore its smooth appearance. 　　 71. How to measure the length of a certain element? 　　Method 1: Use linear annotations or aligned annotations with a measurement unit scale factor of 1. 　　Method 2: Use the dist command. 　　Method 3: Use the list command. Recommended for use. 　　 72. How to change the size of the crosshair? 　　Tools--Options--Display--Crosshair size; adjust it as needed. 　　 73. How to change the size of the selection box? 　　Tools--Options--Selection--Pick Box Size, and adjust it accordingly. 　　 74. How to change the size of the auto-capture marker? 　　Tools--Options--Sketch--Auto-capture marker size; adjust it as needed. 　　 75. What should I do if the copied graphic is always placed far away after pasting? 　　Use base-point copying when duplicating: Point Editing -- Copy with Base Point. 76. How to measure the length of multi-segments with arcs? 　　Use the list command! 　　 77. Why is the stack button unavailable? 　　Usage of stacking: First, there must be stacking symbols (#, ^, /) ； Second, the content to be stacked must be selected before any operations can be performed. 　　 78. What are the concepts of regions, blocks, and solids? A region is a two-dimensional area created by a closed shape or loop ； A block is a collection of objects that can be combined to form a single object (or known as a block definition); one diagram can generally serve as a block within another diagram ； There are two concepts related to entities: one refers to the tangible basic elements that make up a shape, and the other refers to three-dimensional objects. For three-dimensional entities, \"Boolean operations\" can be used to combine them, while for broader types of entities, \"blocks\" or \"groups\" can be utilized for combination. 　　 79. What is the DXF file format? 　　DXF – Drawing Exchange File is a type of ASCII text file that contains all the information from the corresponding DWG file. Although it is not in ASCII format and thus has poor readability, it allows for fast creation of graphics. DWG files from different types of computers – such as PCs and their compatible machines, as well as SUN workstations with different CPU architectures – cannot be exchanged, even if they use the same version of the file. To overcome this limitation, AutoCAD introduced the DXF format, which uses ASCII code; this enables different types of computers to exchange graphics by sharing DXF files. Due to its good readability, DXF files can be easily modified and programmed, allowing for editing and alteration of external graphics. 　　 80. What is an acad “dumb graph”? 　　Ready-made drawings that contain only lines and dimension lines, but no dimension values. This was a lazy practice in previous production; using computer-aided design, such an approach should no longer be advocated. 　　 81. How can lower-version AutoCAD open drawings created in higher versions? 　　Convert it; conversion software can be used ； Or ask the person who sent it to save it in a lower version format before opening it. 　　 82. Solve the problem of large white areas in the control panel after installing CAD 2002. 　　The method is as follows: Open ----- type regedit in the box to launch the Registry Editor, locate the entry HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall\{5783F2D7-0101-0804-0002-0060B0CE6BBA}, modify the DisplayIcon value, and change the -1 in \"AutoCAD 2002 installation directory\acad.exe,-1\" to 1. This will resolve the issue of a large white area appearing when deleting items in the control panel. 　　 83. How to make a graphic view-only and not editable? 　　If it’s your own image, just lock all its layers; it won’t change when opened ； If you don’t want to use it in the future, you can also blow up everything inside ； Another method is to write an encryption program in Lisp; once it runs, the image can only be viewed and cannot be modified in any way. 　　 84. How to modify the association of dimension annotations? To make them associated: select the dimension annotation that needs to be modified and use the DIMREASSOCIATE command. To make them unassociated: select the dimension annotation that needs to be modified and use the DIMDISASSOCIATE command. 85. After converting from *.T to *.dwg, how can the aspect ratio of Chinese characters be changed? In the text properties: it can be modified this way; alternatively, the alignment and direction settings can be adjusted in the CAD2004 properties.