Essentials of AutoCAD Tips

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1. Selection techniques When selecting elements for editing, it’s possible to accidentally select too many of them. In such cases, there’s no need to cancel the command and start over; instead, simply enter “remove” after the “Select target” prompt, then choose one by one the elements that were selected in excess (try not to select too many, or it will be difficult to choose!). When making selections, type any two letters, such as “mn”. You’ll then see a list of options appear in the command line, including “fence”, “wc”, “wf”, etc., which is very convenient. 　　2. AutoCAD cropping techniques As shown in the figure, to crop the lines outside a certain circle (or any other boundary) in the right-side image, the usual method is to select the cropping boundary first and then the line segments that need to be cropped. In fact, AutoCAD offers a simpler way to do this, as follows: (1) Execute the cropping command as usual, and select the cropping boundary (press Enter to confirm) ； 　　⑵. When prompted to select the line segment element to be clipped, enter “f” (i.e., fence) and press Enter to confirm ； 　　⑶. As indicated under \"First Fence point\", draw a continuous rubber-band-like straight line that intersects the segment to be clipped, then press Enter to confirm (see illustration). 　　Two points still need attention: 1. The straight line of the rubber band does not need to be closed ； 2. When the rubber band’s straight line intersects the segment to be cut multiple times, cut off the part from the next intersection onward (this is very important). 　　3. Selection techniques Users can select targets one by one using the mouse, with each selected target being added to the selection set. In addition, AutoCAD provides various window-based methods for selecting targets, such as Window (by typing “w” to respond to Select object: or by drawing a rectangular box from right to left on the screen to respond to Select object:), Crossing (by typing “C” to respond to Select object: or by drawing a rectangular box from left to right on the screen to respond to Select object:), Cpolygon (by typing “CP” to respond to Select object:), and Wpolygon (by typing “WP” to respond to Select object:]. The Window and Crossing methods use rectangular windows, while Wpolygon and Cpolygon use polygonal windows. With the Window and Wpolygon methods, an entity is selected only when all of its parts are contained within the window; whereas with the Crossing and Cpolygon methods, the entity is selected as long as at least one part of it is within the window. AutoCAD also provides the Fence method (by typing “F” in response to Select object:) to select entities; a non-closing polyline is drawn, and all entities that intersect this polyline are selected. When selecting targets, it is sometimes possible to accidentally choose ones that should not be selected. In such cases, the user can type R in response to the “select objects:” prompt to remove the incorrectly chosen targets from the selection set, then type A to add new targets to the selection set. When the selected entity is next to another entity, hold down the CTRL key and then click the left mouse button repeatedly; the adjacent entities will be highlighted one after another until the selected entity is highlighted. After that, press Enter (or click the right mouse button) to select that entity. It is also possible to select entities conditionally, by using ‘Filter’ to select objects. In AutoCAD 2000, there is also the QuickSelect method for selecting entities; it functions similarly to Filter, but is simpler and more convenient to use. AutoCAD’s functions for creating selection sets are very powerful; using them in a flexible manner can **improve** drawing efficiency. 　　4. How to reference ACAD’s form and tolerance symbols in a WORD table? It’s actually simple, but some beginners are too hesitant to try it! ⑴ Set the background color in ACAD to white, as WORD cannot handle background colors; ⑵ In ACAD, create the form and tolerance symbol frame separately and ensure it is displayed at full size to cover the entire drawing area; ⑶ Use ACAD’s “Copy to Clipboard” command to select the form and tolerance symbol frame; ⑷ Switch to the WORD table and paste it there. However, the entire table will become messy as a result. In this case, be patient and use WORD’s built-in image editing functions to trim away any extra edges of the frame, then drag and drop the image into the table so that it fits within the appropriate size. To make the operation easier, you can increase the display scale of the document. 　　5. How to add commands and corresponding icons to the ACAD toolbar Taking CAD 2004 as an example, the CAD toolbar does not display all available commands; users need to add them themselves when necessary. 　　For example, if the multi-line command (mline) is not available by default in the drawing toolbar, it must be added manually. 　　The steps are as follows: View -> Toolbar -> Command tab; select the option to display relevant commands in the window on the right side of the drawing area. Then find “Polyline”, click left mouse button to select it; if it is not placed in any existing toolbar, it will appear as a separate toolbar ； Otherwise, it becomes part of the existing toolbar. 　　At this point, it was discovered that the newly brought-up “Multi-Line” command had no icon! ! We need to add an icon for him. 　　Here’s how to do it: After dragging out the command, do not close the custom window. Click on the “Multi-line” command, and in the lower right corner of the panel that appears, select the appropriate icon for it! 　　At this point, we can also see that CAD allows us to customize icons for each command. This makes it easy to create a personalized toolbar! ! 　　Finally, to delete a command, repeat the above steps: drag the command you want to delete back, and then select “Yes” in the confirmation prompt. The screenshots below show the sequence of operations: 6. Variables ⑴. System variables ①. When using AutoCAD, it can be observed that the dialog boxes within commands turn into prompt lines; for example, the print command is controlled by the system variable CMDDIA, and turning this variable off will resolve the issue. 　　②Whether the ellipse generated by the ellipse command is a polyline or an ellipse as a solid is determined by the system variable PELLIPSE; when it is set to 1, the resulting ellipse is a PLINE. 　　③.DIMSCALE determines the scale of dimensioning; it is an integer, with a default value of 1. It is advisable to change this value to the actual scaling factor once the drawing has been scaled to a specific ratio. 　　⑵Operations: ⑴. BREAK splits an entity at two points; if “@” is used to select the second point, the entity can be split from the first point. 　　⑵.In AutoCAD R14’s BONUS there is an ARCTEXT command that allows for the insertion of text along arcs; to use it, first select the arc, then enter the text content and press OK. 　　⑶.In AutoCAD, files can be inserted into other files as blocks. However, too many blocks can make the file too large; use PURGE to remove them, removing one layer at a time – you’ll need to do this several times! 　　7. Common shortcut keys can improve your drawing speed! 　　F1: Get help 　　F2: Switch between the drawing window and the text window 　　F3: Control whether automatic object snapping is enabled 　　F4: Digitizer control 　　F5: Switch between isometric planes 　　F6: Control the way coordinates are displayed on the status bar 　　F7: Control the grid display mode 　　F8: Control the orthographic mode 　　F9: Control the grid snapping mode 　　F10: Control the polar mode 　　F11: Object tracking control 　　Ctrl+B: Control 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 the grid display mode (F7) 　　Ctrl+J: Repeat the last command 　　Ctrl+K: Create hyperlinks 　　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 the polar mode (F10) 　　Ctrl+V: Paste 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 　　8. A few more things about CAD layers 　　Layer functionality provides great convenience for managing engineering drawings; with it, we can easily create and modify graphics. Therefore, it is essential for every beginner to master knowledge about layers. 　9. How to calculate the area of 2D graphics in AutoCAD: In AutoCAD, it is possible to calculate the area (as well as the perimeter) of 2D closed shapes in a convenient and accurate manner; however, the calculation methods vary depending on the type of shape. 　　⑴. For simple shapes, such as rectangles and triangles. Simply execute the AREA command (which can be entered via the command line or by clicking the corresponding command icon). After the prompt \"Specify first corner point or :\\" appears, turn on snap mode and select the intersection points of the rectangle or triangle one by one, then press Enter. AutoCAD will automatically calculate the area and perimeter, and display the results on the command line. 　　⑵. For simple shapes, such as circles or other two-dimensional closed shapes composed of polylines or splines. Execute the AREA command; after the prompt \"Specify first corner point or :\\", select the Object option, and choose the shape for which you want to calculate the values. AutoCAD will then automatically calculate the area and perimeter. 　　⑶For complex closed shapes composed of simple lines and arcs, the AREA command cannot be used directly to calculate the area of the shape. First, use the Boundary command (whose usage is determined by selecting the appropriate option in the dialog box shown below; it is used to create a region from a shape whose area is to be calculated). Create a region or polyline object from the shape for which you want to find the area. Then execute the AREA command. When the command prompt reads “Specify first corner point or :”, select the Object option and choose the region that was just created. AutoCAD will then automatically calculate the area and perimeter. 　　10. Tips for Replacing Fonts in AutoCAD When exchanging AutoCAD files, it is often necessary to specify replacement fonts because designers use or possess different fonts (especially single-line fonts required in earlier versions). As shown in the figure below, since the UMHZ.shx font was not available on my computer, I had to use the hzkt.shx font that was available on my system instead. 　　This prompt appears every time AutoCAD is started when opening an existing file. In fact, this font replacement can be specified at once in the configuration: Run the config command, enter the font file and its full path in the shaded area of the dialog box shown below (where the font file to be replaced is specified). After clicking OK, the prompt for font replacement will no longer appear the next time AutoCAD is started to open an existing file. 　　11. How to use AutoCAD skillfully 　　① Changing the size of the crosshair 　　---- When creating engineering drawings, it is necessary to draw according to the principles of projection. To facilitate \"alignment in length, evenness in height, and equal width,\" the size of the crosshair can be adjusted during drawing. Use the Options command or select the drop-down menu Tools/Options to open the Options dialog box. Navigate to the Display tab, and by modifying the percentage of the cursor size relative to the screen size in the Crosshair Size field, or by dragging the slider, you can change the default value of 5% and increase the size of the crosshair in the drawing window. 　　②、 Draw with a thick solid line 　　---- Technical drawing **standards specify the line types to be used in mechanical drawings. There are several ways to draw thick solid lines in AutoCAD 2000, and the simplest method is to use the lweight command. This command can be entered directly in the command line, or you can select the drop-down menu Format/Lineweight; in the resulting dialog box, set the desired line width. The default line width is 0.25 mm, and the slider can be used to adjust the scale at which the line width is displayed on the screen. This is a transparent command. You can also click the layers icon on the object properties toolbar; in the Layer Properties dialog box, you can set the line width just as you would set color and line style. Therefore, when the plotter generates the output, there is no need to adjust the pen width or line width anymore. 　　③Draw curves ---- When creating diagrams, it is common to encounter the need to draw intersection lines, tangent lines, 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 broken lines on a 3D shape that pass through specific points, and then fitting them with a spline curve via the Pedit command, can result in a smooth spatial curve. 　　---- Method 2: Use the Solids command to create basic 3D solids (cuboids, 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 projection views of the curves. 　　④Control of entity display ---- In AutoCAD 2000, three system variables can be entered using the keyboard 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 display 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 entities after they have been processed through HIDE (hiding), SHADE (coloring), and RENDER (rendering). The valid range is 0.01–10.0, with a default value of 0.5. The higher the value, the smoother the display, but the waiting time before display appears increases when using the HIDE, SHADE, and RENDER commands. Usually, its value is increased only during the final output. 　　⑤Opening multiple graphic files simultaneously – During the drawing process, users need to view multiple graphic files at the same time; AutoCAD 2000 provides the capability to open multiple graphic files in one window at once (see Figure 5). Select the Window dropdown menu and choose to arrange the graphic files overlapping, horizontally, or vertically. It also allows the graphics from one graphic file to be directly dragged into another using the mouse, which greatly facilitates the design process. 　　⑥Modify graphic properties ---- In drawing, the property window allows for easy and convenient modification of the properties of a specific object within the graphic. You can use the Properties command or select from the drop-down menu Tools/Properties; alternatively, you can use the shortcut Ctrl+1 to open the Properties dialog box, and then select the items you wish to modify as indicated in the table. 　　⑦Design Center Management – Design work is carried out using AutoCAD 2000. With the new Design Center management system, it’s easy to preview, select, search for, and utilize all existing design results. You can obtain the required graphic resources from your existing files, the local network, or even the Internet, add them to the Design Center, or drag them directly into the current drawing. The DesignCenter window can be opened using the AdCenter command, by selecting the Tools/AutoCAD DesignCenter option from the dropdown menu, or via the shortcut key Ctrl+1. 12. Entering special symbols in CAD We know that the symbol “Ф” used to represent diameter, “±” for the horizontal plane, and the degree symbol “°” can all be entered using control codes %%C, %%P, and %%D. But what about entering other symbols? We can enter special characters using a “character mapping table”. The specific steps are as follows: ⑴. Enter the “MText” command, then create a text box; this will open the “Multiline Text Editor” dialog box. In this dialog box, we can see that among the four buttons on the right side, one of them is a button ； 　　⑵Click the arrow in the lower right corner of this button to open a dropdown list; we can see four options: “Degress %%d”, “Plus/Minus %%p”, “Diameter %%c”, and “Non-breaking Space”. By selecting one of the first three options, we can directly enter the symbols “°”, “±”, and “Φ”, thus avoiding the hassle of having to remember special control codes. 　　⑶When clicking “Other”, the “Character Mapping Table” dialog box will open, which contains more symbols for the user to choose from. Its contents depend on the font selected by the user from the “Font” dropdown list. Its interface is entirely in the familiar Chinese layout, so I believe there should be no issues for everyone. 　　⑷In the “Character Mapping Table” dialog box, select the character you want to use. Then double-click on the selected character, or click the “Select” button and then the “Copy” button to copy the character to the clipboard. Click “Close” to return to the original dialog box. Place the cursor in the location where you want to insert the character, and use “Ctrl+V” to paste the character from the clipboard into the current window. 　　13. Introduction to Model Space and Paper Space Auto CAD has two different spaces: model space and paper space (using the LAYOUT tab). There are likely many CAD experts who don’t fully understand these two concepts either. So, let’s start by understanding their characteristics:
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?? Characteristics of viewports in model space:
? ?⑴. In model space, it is possible to draw two-dimensional graphics and three-dimensional models at full scale, along with dimension annotations. 　　?? ⑵. 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. 　　?? ⑶. Use the VPORTS command to create viewports and set their parameters, and these can be saved for later use. 　　?? ⑷、The viewports are tiled; they cannot overlap and are always adjacent to each other. 　　?? ⑸、At any given moment, only one viewport is active; the crosshair can appear in only one viewport, and it is possible to edit only that active viewport (for tasks such as panning and zooming). 　　?? ⑹. Only the active viewport can be printed ； If the UCS icon is set to ON, it will appear in each viewport. 　　?? ⑺. The system variable MAXACTVP determines that the range of the viewport is from 2 to 64. 　　?? Characteristics of the viewport in the drawing space: ?? ⑴ PAPER on the status bar has replaced MODEL. 　　?? ⑵, 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.) 　　?? ⑶, The boundaries of the viewport are solids. You can delete, move, scale, and stretch the viewport. 　　?? ⑷, there are no restrictions on the shape of the viewport. For example: circular viewports, polygonal viewports, etc., can be created. 　　?? ⑸、The viewports are not tiled; they can be overlapped or separated using various methods. 　　??⑹. Each viewport is on the layer that created it; the boundaries of the viewport have the same color as the layer, but the line style of those boundaries is always solid. When exporting the image, if you do not want to include the viewport in the print, you can place it on a separate layer and freeze it. 　　?? ⑺, Multiple viewports can be printed simultaneously. 　　?? ⑻. The crosshair can extend continuously, passing through the entire graphics screen, independent of each viewport. 　　?? ⑼ The MVIEW command can be used to open or close viewports; the SOLVIEW command is used to create viewports, while the VPORTS command is used to restore viewports that have been saved in model space. By default, viewports are active once they are created. Closing some viewports can increase the redraw speed. 　　?? ⑽ To print a graphic while hiding the hidden lines of the 3D graphics, use the MVIEW command > HIDEPLOT and select the viewport boundaries that are to be hidden. 　　?? ⑾. The system variable MAXACTVP determines that the number of viewports in active mode is 64. 　　?? 　　?? Through the explanations above, I believe everyone now has a clear understanding of these two spaces. But keep in mind: 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). 　　14. 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. Various special points on that object (such as the endpoints, midpoint, perpendicular points of a line; the intersection points with the object; the quarter points, center point, tangent points, and perpendicular points of a circle) will be displayed in turn. Select the desired point by clicking with the left button 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. 　　Additionally, for the center point of the circle in version R14, the original tangent points in versions R14 and R2000, and the vertical point when perpendicular to the extension of that line, it is difficult to locate these points using only automatic snapping (Object Snap). By using the aforementioned method of “using the TAB key for assisted snapping,” it becomes easier to locate these points. 15. The acad.lsp editing commands can be utilized to improve work efficiency. For example: (DEFUN C:3 () (COMMAND “ZOOM” “0.50X”) (PRINC)). By pressing 3, the screen is immediately zoomed in. Another example: (DEFUN C () (COMMAND “PURGE” “A” “*” “N”) (PRINC)). 16. Tables in CAD can be imported similar to tables in Excel. ⑴ Select the table in Excel; use thin lines for the table borders, then copy it. ⑵ In CAD, use selective paste under the editing options and choose “Autocad entities”. ⑶ Select the insertion point; you’ll find that the inserted table lines are not aligned. Use inverse selection to select all the vertical lines (many horizontal lines will also be selected; we will select them in the next step). Hold down Shift while selecting the table lines, making sure not to include all the vertical lines as well, otherwise they too will be selected. Now only the vertical lines remain; move them to align properly, and trim any excess lines at the top-left corner. The table is now complete, and it looks exactly the same as if you had drawn each line manually and entered the values one by one. 　　⑷It’s not perfect yet, as the font size isn’t consistent with your image; we’ll fix that issue now. Select a text element in the table, check its height, and use Windows’ built-in calculator to determine the difference in ratio between that height and the size you desire for the text; then use the scale function to adjust the text size to your desired level. If you also want to set a width coefficient for the text, in order to achieve the same alignment as what you see in Excel, define the table as a block first; when inserting the block, select the coefficient for the x-direction, which is the width coefficient of the text – and that’s it. AutoCAD 2000 not only provides Object ARX, an object-oriented C++ application programming interface, but it also offers Microsoft Visual Basic for Applications (VBA), which allows developers to create modules to customize and expand AutoCAD’s functions. (See the ActiveX and VBA Developer’s Guide in the AutoCAD Help.) It also boasts stronger 3D modeling, editing, and modification capabilities, as well as network functions, compared to AutoCAD R14.