This paper introduces CAD drawing skills, editing skills, block processing skills, text and annotation skills.

Keywords: CAD drawing skills

Painting skill

How to draw an elliptical arc

The key to drawing an elliptical arc is to draw a complete ellipse first, and then move the cursor to delete a part of the ellipse. Leave the required elliptical arc.

First, type the ellipse or select the ellipse icon.

The options are as follows: arc/center/

Type: arc

Draw an ellipse in any way. Then prompt for the required arc segment information:

Response: Parameter/

Type: 0 or select a point on the screen that represents the starting point of the angle.

The starting angle is defined as the starting point of the arc.

Response: Parameter/Include/

Select the ending angle that defines the arc length. You can also type i, and then type the 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, which is not suitable for the center and radius of the arc. The following methods can be used.

First draw a polysemous line in the direction and draw a smooth curve. Then choose as many points as possible, which are the vertices on the curve. Then type PEDIT to select polysemy lines.

There are two options: fitting or spline curve. The Fit subcommand will ensure that the curve passes through each vertex, while the Spline subcommand will generate a smoother curve because the curve does not necessarily pass through the vertices. If you need to straighten the curve, you can use the DECURVE subcommand for fitting or spline curves in PEDIT.

A more mature method of using SPLINE command or SPLINEDIT will be introduced in the middle chapter of this book.

Type PLINE and draw multiple line segments, and then randomly select some points. Like drawing five or six dots.

Type: pedit (or select from the Modify toolbar. )

Response: Select a polyline

Select any point on the polysemy line.

Response: Close/Connect/Width/Edit Vertex/Fit Curve/Splice Curve/De-Curve/Undo/Exit

Type: f

Fitting curves to generate curve patterns.

Response: Close/Connect/Width/Edit Vertex/Fit Curve/Splice Curve/De-Curve/Undo/Exit

Type: s

Spline curves produce curve patterns.

Type:

This will terminate the PEDIT command.

How to draw polygons

You can always draw polygons with normal lines or polysemy lines, but AutoCAD has a polygon command. When typing a polygon, you first need to enter the number of sides, and then choose the center or side length. If a point is selected, it will be regarded as the center. There are two additional options: for an imaginary circle, polygons can be inscribed or circumscribed.

If you choose an edge length instead of the center, you must enter the start point and end point of the polygon edge. Then construct the polygon counterclockwise.

Type: Polygon (or select from the drawing toolbar. )

Response: Number of sides:

Type: 5

Response: edge/

Select a point.

Response: Questioning in the circle/circulating in the circle (I/c):

Type: I

Response: radius of circle:

Select a point or enter the radius from the center of the polygon to the circle.

It is worth noting that these polygons can be regarded as independent closed polysemy lines. AutoCAD doesn't care how they were created in the first place. If you decompose a polygon, it will become an independent line.

How to use isometric drawing

Starting from R 10, drawing by isometric method is usually not the first choice for drawing structures. Although AutoCAD has isometric measurement function, if it is R 10 or higher, it will use 3D function to construct the model, and then type DVIEW or VPOINTS to observe the design by isometric measurement.

The isometric function of AutoCAD is accessed by SNAP command, and its sub-option style controls the isometric mode. Under this option, you can choose standard mode or isometric mode. Once you enter isometric mode, Ctrl+E will activate the top, right or left face. Once the correct plane is obtained, the object can be drawn.

The difference between 3D function and isometric capture mode is that 3D generates a real-size model, while isometric capture mode distorts the entity, which is not what it looks like.

Smooth technique

This is a technique to use the sketch command. If you draw a very smooth curve, you can type SKETCH to draw the outline of the surface, which will produce more vertices than expected. After drawing, the sketch object is converted into a polysemous line with PEDIT, that is, the first object is converted into a polysemous line, and then a window is covered on the curve to connect it with other objects. After converting and connecting lines, you can type SPLINE or FIT CURVE to smooth them.

Warning: Try to use SKETCH as little as possible, it has too much storage.

Editing skills

How to Restore Deleted Objects

The simplest and most effective way to restore deleted objects is to use the OOPS command, which can restore the recently deleted selection set. Note that OOPS restores the entire selection set, not just the last deleted object. In addition, OOPS only restores the last deleted group. If you want to recover more steps, alas, you can't.

If you need to restore the objects in the multi-choice set, you can use the UNDO command, but this will bring some other risks, such as some things drawn in the diagram may change. The only problem with the UNDO command is that although you can undo any extra commands issued in the past, if you undo all the erase commands, the result of the undo is normal, while if you undo the erase command, the result of the undo is normal, and if there are other commands between the erased erase commands, you will lose these commands.

How to arrange multiple objects in a ring

In earlier AutoCAD versions, this command was called a circular array, but now it is a circular array. Type ARRAY, then select the object and confirm. You will be asked whether to choose a rectangular array or a polar terrain array. Type p for polar terrain array, and then select the center point of the array around which the object will generate the array. Then, they will be asked three more questions: the number of items in the (1) array; (2) Filling angle; (3) The angles between the items in the array. You must answer any two of these questions.

Let's look at the first question-the number of items in the array. AutoCAD needs to know how many items (including copied items) are in the finished array. If you don't want to answer this question, please press enter or space bar.

The next question is the filling angle, that is, how far you want the objects to arrange around the circle. Enter a positive number to indicate clockwise arrangement, enter a negative number to indicate counterclockwise arrangement, and press Enter to indicate the default value of 360 degrees. AutoCAD knows the distance required to fill 360 degrees with the number of items in the array. If you don't want to answer this question, enter 0 to indicate that the filling angle is 0. The third problem is the angle between the items in the array. If you enter a positive number, the array is arranged clockwise; If you enter negative numbers, they will be arranged counterclockwise.

AutoCAD measures the distance from the center point of the array to any reference point determined by the object structure.

The last option is whether to rotate the object when copying it. Enter y for rotation and n for no rotation.

Type: Array (or select from the Modify toolbar. )

Response: Select object:

Select the object to copy and confirm.

Response: Rectangular or circular array (R/P)

Type: p.

Response: Center point of array:

Select the center point around which the array rotates.

Response: Number of items:

Model: 10

Response: filling angle (+= counterclockwise,-= clockwise) < 360 >; ：

Type:

Response: Rotate objects when copying? & ltY & gt：

Type:

Generate 10 rotating objects around the center point.

How to merge two lines into one object

First of all, suppose that these two lines or a group of lines are not polysemy lines, but ordinary objects such as straight lines or arcs. PEDIT type. When asked to select polysemy lines, select an object from the polysemy lines to be merged. Then tell you that the object is not a polysemous line and ask you if you want to change it to a polysemous line. Type y to indicate agreement.

Next, select Join from many standard options. AutoCAD requires you to select objects to merge. You can select objects one by one, open a window or select objects to merge across windows. If there are disconnected 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 selection is not a polyline. Do you want it to become one?

Type: y.

Response: Close/Connect/Width/Edit Vertex/Fit Curve/Spline.

Bending/Deflexing/Undo/Exit & ltX>:

Type: j.

Response: Select object:

Select all the objects to be merged by opening the window or crossing the window and confirm. Press enter to exit the PEDIT command.

How to enlarge or reduce an object

You can use the Zoom command to change the size of an object. First, type SCALE, and when prompted, select the object to adjust. Then select a basic cold spot anywhere on the object. If the scale factor is selected, the object will be reduced by a factor less than 1, for example, 0.5, so that the object will be reduced by one time.

Option reference is the most interesting one. If Reference is selected, you can enter any length after the new length.

For example, if you enlarge the object by 300%, you can enter a scale factor of 3. But what if you want to change the length of person 2.79 to 4? You can use a calculator to calculate, but it is much easier to use the reference option. Reference length 2.97 is the old length and 4 is the new length. AutoCAD can automatically adjust the scale factor.

Remember that the Zoom command will really permanently change the size of the object, so this command is most suitable when drawing multiple objects with different scales in a picture. In other words, if you only use different scales when you output to a plotter, you'd better use the scale option in the plot command.

Type: Scale (or select from the Modify toolbar)

Response: Select object:

Select the object you want to resize.

Response: Base point:

Select a point on the object.

Response:

Model: 25

The object has shrunk to a quarter of its original size.

The Grips dialog box allows you to use grips to change the size of an object. Type DDGRIPS or select Grips from the Options drop-down menu to display this dialog box.

How to move an object to another layer

You can change an object's layer by using the Properties option of the Change command. There is an option called "Layer" in Properties to change the layer. After you enter and confirm the layer name, the object will be changed to a new layer.

Usually, when an object moves from one layer to another, its color is expected to change, but the result is uncertain, because it depends on whether the color of the object is the same as that of the layer or whether it is decided 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 become the color of that layer.

Type: Change (or select from the Modify toolbar)

Response: Select object:

Select the object to change.

Response: Attribute/

Type: p.

Response: What attribute (color /elev/ layer/thickness) is changed?

Type: la

Response: New layer:

Type: third floor

Type: (This ends the change command. )

Use the relative offset copy or move command.

When using the copy or move command, there is a convenient and quick way to copy or move objects, that is, to use relative displacement instead of giving a datum point first and then displacement. Suppose you want to move an object 4 cm to the right and 2 cm up:

Type: Move (or select from the Modify toolbar)

Response: Select object:

Select the object and confirm.

Response: base point or displacement:

Model: 4, 2. (Note that this is a displacement)

Response: Second displacement point:

Type:.

When you press Enter at the second point, AutoCAD treats the first point as a relative displacement, not an absolute coordinate.

The Fillet command can be confusing.

For beginners of AutoCAD, the fillet command is a bit confusing. When R is entered and the radius is given, nothing seems to change. In fact, it will change when the FILLET command is used again. Press Enter or space bar to repeat the FILLET command, and then you can select two lines.

Because AutoCAD tries to use the FILLET command to handle all FILLET options, the fillet command becomes more complicated. Questions about these complexities will be discussed in the intermediate editing chapter of this book.

Measure and divide command

MEASURE and DIVIDE are both commands for dividing lines, but how to divide lines is up to the user. The MEASURE command distributes an infinite number of points equidistantly from the starting point. DIVIDE command divides a line into an infinite number of equal parts. These commands are distributed along the line. If you can see these points, you can capture them.

You can use system variables PDMODE and PDSIZE to give the shape and size of the placement point. PDMODE sets the shape of the point and PDSIZE sets the size.

How to change the tangent of spline curve

Type the SPLINEDIT command or click the edit spline icon.

The Edit Spline icon is located in the Polyline Edit pop-up bar of the Modify toolbar.

Response: Select Spline:

Fit data/close/move vertices/optimize/reverse/undo/exit & ltX>:

If you are editing a spline for the first time and do not use the Refine option, you will get the above option. Once the spline is closed or open, or any optimization options are used, the Fit Data option can no longer be used. First, you must make sure that all points are on the spline curve. You can select the fitting data by typing f.

Response: Add/Close/Delete/Move/Clear/Tangent/Enter/Exit

Type: t

Now you can choose the starting point of a new tangent point and then the ending point of a new tangent point. If you want to keep the original tangent point, just press enter.

How to quickly add multiple vertices on the whole spline curve

Type the SPLINEDIT command or click the edit spline icon.

The Edit Spline icon is located in the Polyline Edit pop-up bar of the Modify toolbar.

Response: Select Spline:

Fit data/close/move vertices/optimize/reverse/undo/exit & ltX>:

The response is related to the previous edit command, which may be the above content, or it may be as follows:

Response: Close/Move Vertex/Optimize/Reverse/Undo/Exit

Type: r

Response: Add Control Point/Upgrade Order/Weight/Exit

Type: e (add control points for ascending order option)

Response: Enter a new order.

Type: 9

Note the number of control points added. You can try to practice with different numbers, but the numbers can only be increased, not decreased.

How to clean up the well diagram

A well diagram is a diagram similar to a crossroads. There are several ways to solve this problem, but one way is to set FILLET to 0.

There is a way to break all kinds of lines from the intersection, but it requires too many operations. The easiest way is to use the TRIM command. When asking about the cutting edge, open a cross window in the area to be cleared, and make sure it is a cross window, not a window (a window that opens from top right to bottom left), because all four lines must be captured. When asked about the object to cut, click X.

Type: Trim (or select on the Modify toolbar. )

Response: Select cutting edge: (projmode = UCS, edgemode = noextend) Select object:

Surround four intersections with windows and confirm.

Response:

Choose a point for each marked with an X. After selecting four points, press Enter to finish.

How to capture the possible intersection of two lines

You can use visual intersection objects to capture (it is not only used for visual intersections in 3D graphics). If there are two lines that are not parallel, and you want to capture their possible intersections without actually intersecting, you should first use an AutoCAD command similar to CIRCLE, then type APP or select the Apparent Intersection option from the Object Sanp menu, and then select the first line and the second line in turn, so that you can capture their possible intersections.

How do I select an object that is covered by another object?

This is an old question. When using three-dimensional surfaces or auxiliary lines, the problem of covering one object on another often occurs.

In order to solve this problem, we can use the "object circulation method". When selecting objects, hold down the Ctrl key to select objects, so that AutoCAD will look for those objects that can be found one by one. For example, if a 3D surface covers a line, the 3D surface will be highlighted first, and the line will be highlighted when you hold down the Ctrl key to continue the object.

Polygon window and cross window

Do you want to open an irregular window or a cross window? You can use the option Wpoly or Cpoly of Select Object, and just enter WP or CP at the prompt of Select Object. AutoCAD prompts you to select the first point (similar to the first corner of a window), then the second point, and finally close the polygon. You can continue to click on other points, which will make the polygon expand continuously. In this way, an irregular polygonal window can be constructed, which just surrounds the selected object. After drawing a Wpoly or Cpoly line, you must press Enter before selecting each object. You are still at the Select Object prompt.

The only difference between WP and CP is that WP has the same function as a window (all objects must be completely inside the window) and CP has the same function as a cross window (the selected object can be inside the window or intersect the window).

How to use BREAK@ on a circle

Have you ever tried to divide a circle into two arcs? You can type BREAK@ to see what happens. As you can see, AutoCAD doesn't allow this. But many times two arcs are needed instead of a circle, even if the two arcs are connected with each other. Break the circle at two points (counterclockwise), the arc between the two points will disappear, and then make another arc with SEC (starting point, ending point and center) to replace the missing arc.

How to capture visible intersections that don't actually exist?

In three-dimensional drawing, it is particularly easy to produce intersections that seem to intersect but do not exist. For example, when the viewing angle is changed to make lines cross, the generated intersection does not actually exist. To snap to intersections on surfaces, type APP after any AutoCAD command, or choose the Appearance Intersection option from any object snap menu. Put the snap box on the intersection of surfaces, and AutoCAD can snap it.

In the earlier version of AutoCAD 13, AutoCAD can only identify the intersection generated by some regular lines, but can't identify the intersection generated by stretching or solid.

There may be some revisions in future versions of AutoCAD. There is a trick in these periods: if you can't capture the intersection due to stretching, you can draw a regular line on the stretching, so that you can capture the visual intersection. You can delete the guide later.

How to reconnect two arcs into a circle

Suppose that the circle is broken into two arcs by the above ring breaking technology, and the two arcs form a complete circle. Don't try to reconnect them into a circle with the PEDIT command. Although the command seems to have been executed, it can't succeed because it is not a circle, but a closed polysemous arc.

The simplest method is to calculate the radius and center of a circle, then erase the arc and redraw the circle.

How to select multiple datum points using the handle.

After selecting the object, click the datum point. If you want to click other datum points at the same time, you can hold down the Shift key while clicking other datum points. Note that you can only click on the datum point, otherwise AutoCAD will think that you want to stretch and copy the selected object.

If you want to stretch a rectangle, you should hold down the Shift key first. Click the datum points of three adjacent lines, and then release the Shift key. To activate the selection set, click one of the above datum points again to start stretching.

How to Transform Spline Curve into Polysemy Curve

Disassembling is impossible, but there is a trick: erase all objects except splines in the diagram. When asked to select objects, type ALL, then type r to delete all objects except spline curves, and finally confirm the selection set. Now there is nothing in the picture except spline curves. Type the command savesr12 and give the drawing name, so as to save the spline as an object of AutoCAD 12. Because there is no spline curve in AutoCAD 12, spline curve is regarded as a polysemy object.

Type OOPS and press Enter to restore the rest of the chart, erase the spline, and type a file that is saved only after insertion at 0,0. Be sure to add an asterisk (*) before the chart name to ensure that the definition of block is not established and the chart will not be loaded as a block.

How to extend an object with a handle

First, select one or more objects to extend, and then all handles will be displayed. A handle has been selected. When the mouse is near the handle, it will be caught on the handle. Once the handle is selected, its color will change to indicate that a datum point is selected, and it will automatically be in extension mode. This is an illusion at present, because only the position of the handle point can be extended. If the extended object is a line and the reference point is the midpoint, the whole line will move to the new position without being extended as long as it is clicked at another position on the screen. If the reference point is the end of the line, click another position on the screen and the end will move to that position. It can be seen that different datum points have different results. Generally speaking, if you choose the midpoint of a line, the center of a circle, or the insertion point of a text or block, then the way to expand is to move these objects.

How to use handles to move objects

Hold down the Shift key, select one or more objects to move, and the handle will be displayed. Release the Shift key, and then select any handle as the reference point, which is automatically in the extension mode. This can move the whole object, but it must be based on the center or midpoint.

In move mode, you can use any point as a reference point to move an object. Type MO or press Enter to enter the mobile mode, and press the space bar to switch back and forth between the mobile mode and the extended mode. (Select Move from the on-screen menu to enter the mobile mode. How to Draw Section Lines of Wall Parts

Suppose this wall is more complicated than simply offsetting polylines. Drawing section lines becomes more complicated when wall segments are interrupted by doors, windows or other elements. The section line should be cut after all the doors and windows are inserted. It is a big mistake to try to insert these parts into the area where the section line has been drawn. To do this, you have to break the section line and clean up the section line area, but too many objects are generated. Besides, what if I want to move the door?

The first thing to do is to ensure that all the components have been inserted, then create a new layer named "Outline", use PLINE to track the wall area, make sure to stop at the beginning of the door or window, then close the polysemy line and continue working until all the areas to be cut are closed with polysemy lines.

When all the areas to be patterned are closed, it is easy to pattern each area. The section must be drawn on a different layer from the contour layer to make its visibility easy to control.

How to keep the size of the point constant relative to the screen size?

The system variable PDSIZE can be used to resize points or nodes. The problem is that this is an absolute size, so when you zoom in on an area, the size of the point will also increase.

The following methods can keep the size of the point constant relative to the screen size, regardless of the scaling factor. Take a negative value when typing PDSIZE. After that, the size of the zoom point will not change. You can also display it in the Point Style dialog box by typing the size of the DDPTYPE setpoint, expressed as a percentage of the screen size.

CAD/huitu . htm # head # head " & gt； How to close line segments drawn at different times

Usually need to include a set of straight lines and curves. The most convenient way is to edit one of the line segments with PEDIT, convert it into a polysemous line, then type the JOIN command, select all objects with the window, and finally type the CLOSE command. AutoCAD will determine the positions of both ends of all objects and draw a polysemy line to connect them. At this time, this group of objects will become a closed polysemy line.

How to draw an elliptical arc

Any arc is a part of a circle. Just as there is no arc command, you can create an arc by breaking or cutting a circle. You can create an elliptical arc by breaking or cutting the ellipse.

First, create an ellipse. Then interrupt it. The position of the interruption or cut determines the size of the arc. BREAK doesn't work as expected. If the direction is wrong after the interruption, try to draw an auxiliary line at each end of the ellipse to be interrupted, and then use TRIM.

Ellipse is actually a series of polysemous arcs. When an ellipse is interrupted, cut or decomposed, it becomes a component. After the interruption, you should also arch it upward with the PEDIT command, so as to truly form an elliptical arc.

If it is guaranteed to control the start and end of multiple lines.

Type MLSTYLE or select the multiline style icon. Select the style you want to change from the Multiline Style dialog box. Select multi-line properties ... A dialog box will appear. Under Endpoints, select the check boxes to add end tags to the start and end points of the line. You can place an arc on two outer or inner line segments. You can also display connections, that is, lines placed when you rotate the corners of the lines. Lines can be filled and colored.

Multiline style icon, located in the object properties toolbar.

New use of line length

PLINE's Length subcommand is not often used because it only draws polysemy lines from known points in the same direction and angle as the previous line or polysemy line. Length is not more useful than extending a line exactly. But with a little consideration, you can get more uses.

To position some points relative to other points on the map, you can use the Relative Coordinates command or redefine the UCS. But these two methods are usually inconvenient, especially if the angle of the line.

Please look at a practical example. Suppose a series of lines or polysemy lines are drawn. Pay attention to the direction of the polysemy line. The goal now is to locate a point three units before the previous point. You usually need to close the current line here and start drawing another line or ID again to position it relative to another point.

This is a very troublesome thing, but using PLINE's Length subcommand is relatively simple.

Type: pline

Response: From point:

Select the previous point.

Response: Arc/Closed/Half Width/Length/Undo/Width/

Type: l

Response: Line length:

Type: -3 (You can also type other positive and negative values. A positive value will lengthen the line, and a negative value will indent along the polysemy line. ) Now the terminal of this line is 3 units away from the previous line. You can use the opposite ID and close the new polysemous terminal.

Text and crosshatch combination

If you need to put text or other objects in shadow mode, make sure to make room for the text first. Draw a rectangle in the object to be hatched, then type the text and erase the rectangle border.

This method can fully control the shape and size of the blank area around the text. If you type text first, and then draw a section line. AutoCAD can control blank areas. This method is especially useful when typing multiple lines of text.