CAD drawing skills

Thread Content

summary: The article introduces key words such as CAD drawing skills, editing skills, layer block processing skills, text and annotation skills, etc.: CAD Drawing Tips Drawing Tips How to Draw an Elliptical Arc The key to drawing an elliptical arc is to first draw a complete ellipse, then move the cursor to delete part of the ellipse. Leave the required elliptical arc. First, type ELLIPSE or select the Ellipse icon. Options are as follows: Arc/Center/: Type: Arc draws an ellipse using any method. Then you are prompted to enter the required arc segment information: response: Parameter/Type: 0 or the point on the selected screen that represents the starting point of the angle. The start angle is defined as the starting point of the arc. response: Parameter/Included/: Select the end angle that defines the arc length. You can also type I and then wrap angle. The wrap angle is measured from the starting angle, not from 0. How to draw a smooth curve? Although an arc is a curve, it is often necessary to draw a smooth curve that does not conform to the center and radius of the arc. You can do this as follows. First draw a polyline in the direction where you want to draw a smooth curve. Then select as many points as possible, which are the vertices on the curve. Then type PEDIT to select the polyline. There are two options: FIT or SPLINE. The FIT subcommand will ensure that the curve passes through every vertex, while the SPLINE subcommand will produce a smoother curve because the curve does not necessarily pass through the vertices. If you need to straighten a curve, use the DECURVE subcommand on the FIT or SPLINE curve in PEDIT. More mature methods using the SPLINE command or SPLINEDIT will be described in the intermediate chapters of this book. Type PLINE and draw multiple line segments, randomly picking some points. For example, draw five or six points. Type: PEDIT (or select from the Modify toolbar. ) response: Select polyline Select any point on a polyline. response: Close/Join/Width/Edit vertex/Fit curve/Spline curve/Decurve/Undo/eXit: Type: F Fit Curve produces curve patterns. response: Close/Join/Width/Edit vertex/Fit curve/Spline curve/Decurve/Undo/eXit: cad/huitu.htm #head#head">Type: S Spline curve produces a curve pattern. Type: This will terminate the PEDIT command. How to Draw Polygons Drawing polygons can always be drawn with normal lines or polylines, but AutoCAD has a POLYGON command. When typing POLYGON, you are first asked to enter the number of sides, followed by selecting the center or side length. If you pick a point, it is considered the center. There are two additional options: For an imaginary circle, the polygon can be inscribed or circumscribed. If you select Side Length instead of Center, you must enter the start and end points of the polygon sides. The polygon is then constructed counterclockwise. Type: POLYGON (or select from the Draw toolbar. ) response: Number of sides: Type: 5 responses: Edge/: Select a point. response: Inscribed in circle/Circumscribed about circle(I/C): Type: I respond: Radius of circle: Select a point or type the radius from the center of the polygon to the circle. There is one thing worth noting about constructing polygons like this:: These polygons can be viewed as independent, closed polylines. AutoCAD does not care how they were originally created. If you break up a polygon, it becomes an independent line. How to Draw Isometrically Starting with R10, drawing isometrically is not usually the preferred method for drawing isometric structures. Although AutoCAD has isometric capabilities, if it is R10 or higher, you will use the 3D capabilities to construct the model and then type DVIEW or VPOINTS to view the design in isometric mode. The isometric function of AutoCAD is accessed with the SNAP command, and its sub-option Style controls the isometric mode. Under this option, you can choose the standard mode or the isometric mode. Once in isometric mode, Ctrl E will activate the top, right or left face. Once you have the correct plane, you can draw the object. The difference between the 3D function and the isometric capture method is that 3D produces a true-size model, while the isometric capture method distorts the entity. In fact, the entity is not what you see. Smoothing Tips This is a trick using the SKETCH command. If you are drawing a very smooth curve, you can type SKETCH to trace the outline of the surface, which will produce more vertices than you would expect by hand. After drawing, use PEDIT to convert the SKETCH object into a single polyline, that is, convert the first object into a polyline, and then use a window mask to cover the curve and connect it with other objects. Once the lines have been transformed and joined you can type SPLINE or FIT CURVE to smooth them. warn: Try to use SKETCH as little as possible, it has too much storage capacity. Editing Tips How to Restore a Deleted Object The easiest and most effective way to restore a deleted object is to use the OOPS command, which restores a recently deleted selection set. Note that OOPS restores the entire selection collection, not just the last deleted object. In addition, OOPS only restores the last deleted group. If you want to restore more steps, OOPS cannot do it. If you need to restore objects in multiple selection sets, you can use the UNDO command. However, doing so will bring some other risks. For example, some of the drawn content in the picture may change. The only problem with using the UNDO command is that although you can undo any number of external commands issued in the past, if all ERASE commands are undoed, the results of UNDO are normal, and if there are other commands between the undo ERASE commands, the results of these commands will be lost. 　 How to arrange multiple objects into a circular shape. In earlier versions of AutoCAD, this command was called Circular ARRAY, but now it is called Polar ARRAY. Type ARRAY, then select the object and confirm. You will be asked to choose a rectangular array or a polar terrain array. Type P for a polar terrain array, and then select the center point of the array, and the object will be arrayed around the center. Then, you will be asked three questions: (1) Number of items in the array ； (2) Filling angle ； (3) The angle between items in the array. Any two of these questions must be answered. Let's first look at the first question - the number of items in the array. AutoCAD needs to know how many items are in the completed array (including the copied one). If you don't want to answer the question, press Enter or Spacebar. The next question is the fill angle, that is, how far around the circle you want the objects to line up. Enter a positive number to arrange clockwise, enter a negative number to arrange counterclockwise, and press Enter to indicate the default value of 360 degrees. AutoCAD knows the distance necessary to fill 360 degrees with the number of items in the array. If you don't want to answer this question, enter 0 for a fill angle of 0. The third problem is the angle between the items in the array. If you enter a positive number, the array is arranged clockwise ； Enter negative numbers to sort counterclockwise. AutoCAD measures the distance from the center point of the array to an arbitrary reference point determined by the structure of the object. The final option is whether or not objects should be rotated when they are copied. Enter Y to rotate, N to not rotate. Type: ARRAY (or select from the Modify toolbar. ) response: Select Objects: Select the objects to copy and confirm. response: Rectangular or Polar array(R/P) type: P. response: Center point of array: Pick the center point around which the array rotates. response: Number of items: Type: 10 responses: Angle to fill ( =ccw,-=cw): Type: response: Rotate objects as they are copied?: Type: Generate 10 rotating objects around the center point. How to merge two lines into one object. First, assume that these two lines or a group of lines are not polylines, but ordinary objects such as straight lines or arcs. Type PEDIT. When asked to select a polyline, select an object within the polyline you want to merge. You are then told that the object is not a polyline and asked if you want to change it to a polyline. Type Y for yes. Next, select Join from many standard options. AutoCAD requires you to select the objects to be merged. You can select the objects one by one, or you can select the objects to be merged by opening windows or opening cross windows. If there are broken objects in a group of objects, they cannot be merged. Type:PEDIT (or select from the Modify toolbar) Response: Select Polyline: Select an object. response: Object selct is not a polyline.Do you want it to turn into one? Type: Y. response: Close/Join/Width/Edit vertex/Fit curve/Spline urve/Decurve/Undo/eXit: Type: J. response: Select objects: Select all objects to be merged by opening windows or cross windows, and confirm. Press the Enter key to exit the PEDIT command. How to enlarge or shrink an object. Use the SCALE command to change the size of an object. First, type SCALE and when the prompt appears, select the object you want to adjust. Then select a basic cold point at any position of the object. If the scale factor is selected, the object will be reduced by a factor less than 1, such as 0.5. In this way, the object will be doubled. The option Reference is the most interesting one. If you select Reference, you can enter any length after a new length. For example, if you want to enlarge an object by 300 percent, you would enter a scale factor of 3. But what if we want to change the length from 2.79 to 4? You can use a calculator to do the math, but it's much easier to use the Reference option. The reference length 2.97 is the old length and 4 is the new length. AutoCAD can automatically adjust the scale factor. Keep in mind that the SCALE command will actually permanently change the size of the object, so this command is most appropriate when drawing multiple objects at different scales in a single drawing. In other words, if you are only going to use a different scale when outputting to a plotter, it is best to use the Scale option in the PLOT command. Type: SCALE (or select from the Modify toolbar) Response: Select objects: Select objects to resize. response: Base point: Select a point on the object. response: /Reference: Type: 25 The object is reduced to a quarter of its original size. Grips can be used to change the size of objects through the Grips dialog box. This dialog box can be displayed by typing DDGRIPS or selecting Grips… from the Options drop-down menu. How to move an object to another layer Use the Properties option of the CHANGE command to change the object's layer. There is an option Layer in Properties that is used to change the layer. When the layer name is entered and confirmed, the object is changed to the new layer. Usually when an object is moved from one layer to another, you want its color to change, but the result is not deterministic because it depends on whether the color of the object is the same as the layer it is on when you draw it, or whether it is determined by itself. If the color of the object has not changed, you can use the Properties of the CHANGE command to change the color. When asked about the color, type BYLAYER and the object will change to the color of that layer. Type: CHANGE (or select from the Modify toolbar) Response: Select objects: Select the objects to be changed. response: Properties/: Type: P. response: Change what property (Color/Elev/Layer/Thickness)? Type: LA response: New layer: type: LAYER－3 typing: (This ends the CHANGE command. ) COPY or MOVE command using relative displacement When using the COPY or MOVE command, there is a convenient and quick way to copy or move an object, which is to use relative displacement without giving a reference point first and then giving the displacement. Suppose you want to move an object 4 cm to the right and 2 cm upward.: Type: MOVE (or select from the Modify toolbar) Response: Select objects: Select objects and confirm. response: Base point or displacement: type: 4,2. (Note, this is displacement) Response: Second point of displacement: typing: . When you press Enter at the second point, AutoCAD treats the first point as a relative displacement instead of an absolute coordinate. The FILLET command can be confusing. For beginners of AutoCAD, the FILLET command can be a bit confusing. When R is entered and the radius is given, nothing seems to change. In fact, the change only occurs when the FILLET command is used again. Press Enter or Spacebar to repeat the FILLET command, and then select two lines. The FILLET command becomes more complex because AutoCAD attempts to handle all fillet options with the FILLET command. Issues related to these complexities are discussed in the intermediate editing chapters of this book. 　 MEASURE and DIVIDE commands MEASURE and DIVIDE are both commands used to break lines, but it is up to the user to decide how to divide the lines. The MEASURE command distributes infinite points equidistantly from the starting point. The DIVIDE command divides the line into an infinite number of equal parts. These commands place points along the line. If you can see these points, you can capture them. The shape and size of the placement point can be given using the system variables PDMODE and PDSIZE. PDMODE sets the shape of the point, and PDSIZE sets the size. How to change the tangent of a spline Type the SPLINEDIT command or click the Edit Spline icon. Edit Spline icon, located in the Polyline Edit popup bar of the Modify toolbar. response: Select spline: Fit Data/Close/Move Vertex/Refine/rEverse/Undo/eXit: If this is the first time you edit a spline and you have not used the Refine option, you will get the above options. Once you Close or Open a spline, or use any of the Refine options, you can no longer use the Fit Data option. First, you must make sure that all points lie on the spline. This can be done by typing F and selecting Fit Data. response: Add/Close/Delete/Move/Purge/Tangents/to Lerance/eXit: Type: T It is now possible to select the start point of a new tangent point, and then select the end point of a new tangent point. If you want the original cut point to remain unchanged, just press the Enter key. How to quickly add multiple vertices to the entire spline