I. Essential Concepts and Basic Operations
1. CAD consists of many commands, and there are various ways to execute them. Basically, there are two methods: one is to input the command (or select the command button) and then execute the operation; the other is to select first and then execute the command. Many commands can be executed using either method.
Example: To delete an object, you can first select the delete command and then select the object, or you can select the object first and then select the delete command. Both methods produce the same result. (Keyboard input: E + Space + Select Object + Space; or Select Object + E + Space; the result is the same.)
2. Transparent Commands. Most commands have a single execution process, meaning they can only be completed during execution or canceled midway. However, some commands allow another command to be executed while one command is running. That is, command A can execute command B while command B is running, and after command B completes, command A continues to execute until the end. Such commands are called "transparent commands."
3. Methods for Selecting Objects. There are two selection methods: one from top left to bottom right, and the other from bottom right to top left. The results are different. The first method (top left to bottom right) only selects objects completely enclosed by the dragged-out frame. The second method (bottom right to top left) selects all objects intersecting the dotted frame (including enclosed objects).
4. Relative Coordinates: Position relative to the current point (or a point you specify). This is very important! For example, to draw a 1000mm line, select the command, then select any point on the screen, and specify a direction (move the mouse in the desired direction; for horizontal or vertical lines, press F8 to enable Ortho mode), input 1000, and press Enter (or Space). You will get a 1000mm line. This is the simplest example of relative coordinates.
For example, to draw a 1000x1000 square, you need to select the command, then select any point on the screen, and input "@1000,1000" and press Enter (or Space). You will get a square. "@" represents the relative coordinates. Furthermore, if you want to draw a line 1000mm long with a 37-degree angle to the horizontal, select the line command, then select any point on the screen, and type "@1000<37" and press Enter. That's it. You must remember these two methods!
5. Keyboard Operations: a. You can directly enter commands on the keyboard at any time and execute them without needing to click somewhere before entering the command. b. Commands can be entered in full or in abbreviation. c. The spacebar and Enter key have the same function: executing the command. That is, after entering the command, pressing the spacebar or Enter key will execute it. d. To continue with the previous command, simply press the spacebar; you don't need to re-enter the command or select a button.
6. Mouse Operations: Left button: self-explanatory. Right button: Pressing the right button confirms the command execution and ends continuous operations. It's somewhat similar to the spacebar, but also has some shortcuts. When no command is being executed, pressing the right mouse button will bring up a menu; the default first option is to execute the previous command. Explore the others yourself. Scroll wheel: Zoom in and out. Double-click the scroll wheel: Display all current graphics. Holding down the scroll wheel changes the mouse cursor to a "hand" and allows you to move the screen. Turn the mouse around so the laser or scroll wheel is facing upwards, and you'll see an unexpected surprise-the mouse will become unusable.
II. Keyboard Shortcuts and Basic Drawing Preparations
1. F8: On/Off. Orthogonal Mode: When orthogonal mode is on, you can only draw horizontal or numerical lines. Moving or copying objects also only allows horizontal or numerical movement. This is very useful for drawing straight lines, so getting used to using F8 for drawing lines is very important.
2. F3: On/Off. Auto Snap: When on, various yellow symbols will appear when you move the mouse over an object. Different symbols represent different positions, such as □ for endpoints and △ for midpoints. Memorizing these markings is crucial.
3. Setting Snap: The words "Object Snap" are displayed at the bottom of the screen. Right-click on it and select "Settings." You'll see the meanings of various symbols. Select the ones you need, or select all. Click "OK" to set up the snap. The left mouse button functions the same as F3, toggling auto-snap on and off.
4. Displaying Shortcut Buttons. If you're using another computer and find that its AutoCAD doesn't have shortcut buttons or an annotation button, you can bring them up yourself. Right-click in the gray area outside the black area to see the AutoCAD menu. A long list of options will appear, some checked, some unchecked. If you don't see the annotation menu, find it and click on it. The annotation will appear. Then move it to your desired location.
5. CTRL+S Save. To use: Hold down CTRL and press the S key (e.g., use your left pinky finger to press CTRL and your left middle finger to press S, then release). Make it a habit to save after every operation. You can't guarantee your computer won't crash, the power won't stop, or AutoCAD won't encounter a fatal error. If you don't save, you might waste half an hour or more of your work! Therefore, developing this habit is very important! Of course, you can also click the save button above, but I find that troublesome! Once you get used to it, you won't even realize you need to do this, haha, you won't feel it! Remember, this is very important!!!
6. Custom Commands. First, memorize the basic commands, but you also need to define custom commands. To define them, go to Tools-Customize-Edit Custom File-Program Parameters acad.pgp. Many of the parameters start with a semicolon (;). The first one that doesn't start with a semicolon is the command's beginning. Generally, the command below "3A, *3DARRAY" is the part we need to edit. Don't touch anything else you don't understand. For example, 3A represents the shortcut key, and the part after the * sign is the full name of the command. That is, typing 3A and typing 3DARRAY have the same effect. After modifying, save, close CAD, and reopen CAD to use your custom commands.
7. ESC. Press the ESC key at any time to cancel the currently executing command.
III. Basic Commands
1. Line Command (Shortcut: L)
Operation: Type L → Space → Click the first dot on the screen → Click the second dot → Click the third dot → Space. Done. Of course, you can draw indefinitely.
2. Copy command (shortcut: CO; some CAD versions use C): Enter CO → Space → Select the object → Space → Select the reference point → Select the location to copy to → Space to finish. (In CAD 2004, for continuous copying, press M before selecting the reference point; later versions support continuous copying.) To copy an object 1000mm away, enter CO → Space → Select the object → Space → Select the reference point → Enter the relative coordinates → Space. (For horizontal or vertical directions, press F8 to enable Ortho mode, move the mouse to specify a direction, then enter 1000 and press Space.)
3. Move command (shortcut: M): Same as copy.
4. Circle command (shortcut: C; some versions may use CIR CR): Enter C → Space → Click → Enter the diameter → Space or drag the mouse and left-click to confirm.
5. Offset command (shortcut: O): Enter O → Space → Enter the offset distance. 6. **Format Painter Command:** Press the spacebar (or specify a distance on the screen using two dots) to select the object to offset. Click the mouse in the desired offset direction.
7. **Format Painter Command:** Press the MA key and press the spacebar again. Select the reference object and then the object to be painted.
8. **Properties Command:** Press the MO key and press the MO key. Select the object (you can see its properties, coating color, geometric dimensions, etc.).
9. **Array Command:** Press the AR key and press the AR key. A dialog box will appear. If you want to create a 3x4 grid, enter 3 for the row and 4 for the column. Fill in the "Offset Distance and Direction" fields as needed.
10. **Extend Command:** Press the EX key and press the spacebar again. Select the desired extension point and press the spacebar again. Select the line to be extended. Tip: There may be intersecting lines or objects before the line. A small trick: Press the EX key and press the spacebar again. Click the object to be extended to extend directly to the nearest object. Continue clicking the line to extend to the next object.
11. **Trim Command:** Press the TRIM key. TR Operation Method: Same as Extend.
11. Delete Command: ERASE shortcut command E Operation Method: Type E, press Space, select the object, press Space (or select the object and press E, press Space).
12. Undo Command: U Operation Method: Type U, press Space. As long as CAD is not closed, you can undo until you return to the state when the drawing is opened.
13. Explode Command: EXPLODE shortcut command X Operation Method: Type X, press Space, select the object (or select the object and type X, press Space). Note: If it is a block, it may take many explosions to explode it, and some things cannot be exploded.
14. Stretch Command: STRETCH shortcut command S Operation Method: Type S and drag a box from the bottom right to the top left so that the left vertical line or the top horizontal line intersects with the part being stretched, press Space, select a base point, and enter the distance or specify the next point.
15. Mirror Command: MIRROR shortcut command: MI Operation Method: Type MI Select the object to be mirrored, select the first point of the "mirror," select the second point of the "mirror," press space, and you will get an image with the two selected points as the axes of symmetry. III. Why memorize these 15 commands: Because many people know how to operate CAD, but to stand out, you need faster operation to be better than others. Using the keyboard looks cool, and to be a truly skilled person, you need proficient keyboard operation. Simply clicking the mouse on the screen doesn't mean you know CAD. CAD is very powerful, and its operation can be very flexible. To draw a shape, there are many ways to operate, such as drawing a square: Method 1: Use the line command + relative coordinates to form a square. Method 2: Select the rectangle command + relative coordinates to generate a square. Method 3: Draw two perpendicular lines and then use offset to form a square. Method 4: Draw a line and use array (circular array) to generate a square. Method 5: Draw two perpendicular lines, use the copy command to copy both lines, and generate a square. Method 6: Draw two intersecting lines, copy both lines, take the intersection point as the reference point, input relative coordinates, and cut off the excess lines to form a square. Therefore, mastering these 15 commands is almost enough to go anywhere!
