Reversing Objects Using the MIRROR Command

To "reverse a drawing" in AutoCAD typically means creating a mirrored copy of part or all of the drawing, or flipping specific objects like blocks along an axis. Here's how you can achieve this:

The most common way to reverse selected objects in an AutoCAD drawing is by using the MIRROR command. This command creates a mirror image of existing objects.

How to Use the MIRROR Command:

1. Type MIRROR (or MI) in the command line and press Enter.
2. Select the objects you want to reverse (mirror). You can use selection windows or pick individual objects. Press Enter when done selecting.
3. Specify the first point of the mirror line. This line acts as the axis around which the selected objects will be mirrored.
4. Specify the second point of the mirror line. The position and angle of this line determine the orientation of the mirrored copy.
5. AutoCAD will ask "Erase source objects? [Yes/No] ".
   • Type N and press Enter (or just press Enter to accept the default ) to keep the original objects and create a mirrored copy.
   • Type Y and press Enter to erase the original objects and keep only the mirrored copy.

Example: To mirror a shape horizontally, you would pick two points for the mirror line that are vertically aligned. To mirror it vertically, you would pick two points that are horizontally aligned.

Flipping Blocks with Flip Parameters

Another way to "reverse" or change the orientation of an object, specifically a block, is if the block definition includes a Flip parameter. Dynamic blocks can be set up with actions that allow you to easily flip them without using the general MIRROR command every time.

According to instructions based on referencing how to flip a door block in AutoCAD:

Adding a Flip Parameter (for Block Authors)

If you are defining a block and want to make it flippable, you can add a Flip parameter and action within the Block Editor.

1. Select the block you want to edit.
2. Right-click and choose Block Editor from the context menu. This opens the block definition environment.
3. In the Block Authoring palette (usually visible in the Block Editor), navigate to the "Parameters" tab.
4. Click on the Flip parameter.
5. You will be prompted to specify the reflection line. Based on the reference, you click on a midpoint, like the midpoint of a frame or object within the block, to define the axis along which the block will flip.
6. Define the label location for the flip grip.
7. Go to the "Actions" tab in the Block Authoring palette.
8. Click on the Flip Action.
9. Select the Flip parameter you just added.
10. Select the objects within the block definition that you want to be affected by the flip action.
11. Close the Block Editor and save the changes to the block definition.

Using a Block with a Flip Parameter (for Drawing Users)

Once a block definition has a Flip parameter and action added:

1. Insert the block into your drawing.
2. Select the inserted block.
3. You will see special grips appear on the block. One of these will be the Flip grip (often an arrow icon) located where you defined the parameter label location.
4. Clicking this Flip grip will automatically reverse the block along the defined flip axis, simplifying orientation changes.

Summary of Methods

Method	Description	Use Case	Command/Process
MIRROR	Creates a mirrored copy of selected objects.	Reversing lines, arcs, circles, text, blocks, etc.	MIRROR (or MI)
Flip Parameter (Dynamic Blocks)	Adds a built-in flip action to a block definition.	Flipping specific block instances easily.	Add in Block Editor; Use grip on block.

By utilizing either the MIRROR command for general objects or pre-defined Flip parameters for blocks, you can effectively reverse elements within your AutoCAD drawing.