Mastering AutoLISP in AutoCAD: Creating and Loading Your First Custom Routine

Welcome back to AutoCAD Essentials for Mechanical Engineers blog series.  

AutoLISP is one of the most underutilized yet powerful features in AutoCAD essentials. It allows users to automate repetitive tasks, create custom commands, and tailor the software to their specific needs. Whether you're working on AutoCAD 2D or AutoCAD 3D projects, AutoLISP can transform how you approach complex workflows. This blog, part of the AutoCAD Essentials for Mechanical Engineers series, guides you through creating your first AutoLISP routine and integrating it into AutoCAD. 

Step 1: Writing and Saving Your AutoLISP Routine 

Before you can harness the power of AutoLISP, you need to write your routine using a text editor like Notepad. Here’s how to get started: 

Writing Your First Routine 

1. Open Notepad and type the following code: 

(defun C:test () 

  (command "zoom" "all") 

  (command "circle" pause 50) 

) 

•  defun: Defines the function. 
• C:test: Specifies the command name (test) that will be called in AutoCAD. 
• Commands: The zoom and circle commands will execute with specific parameters. 

Saving the Routine 

1. Save the file as test.LSP. 
2. Ensure the "Save as type" is set to "All Files." 
3. Double-check the .LSP extension, as AutoCAD only recognizes files saved in this format. 

Step 2: Loading the AutoLISP Routine 

AutoCAD offers two methods for loading AutoLISP routines: Load Command and AppLoad Functionality. These methods ensure your routine is accessible during your drafting or modeling process. 

Method 1: Using the Load Command 

1. Open AutoCAD’s command line. 

2. Type the following command: 

(load "C:\\Users\\Desktop\\test.LSP") 

• Replace the path with the location of your .LSP file. 
• Use double backslashes (\\) in the file path, as AutoCAD requires this format. 

3. If loaded successfully, the command C:test will appear in the confirmation message. 

Method 2: Using AppLoad 

• In AutoCAD, type appload and press Enter. 
• Browse to the location of your .LSP file. 
• Select the file and click Load. 
• Once loaded, the routine is ready for use. 

Step 3: Executing Your AutoLISP Routine 

1. After loading the routine, you can execute it directly from the command line. Here’s how: 

2. Type test in the AutoCAD command line and press Enter. 

The script will: 

• Zoom to the drawing’s extents. 
• Prompt you to specify the center point of a circle. 
• Automatically create a circle with a radius of 50 units. 

This process demonstrates the power of AutoLISP for automating common tasks in AutoCAD for engineers, reducing repetitive steps and enhancing productivity. 

Bonus: Automating Routine Loading with AutoCAD Startup 

To streamline your workflow further, configure your frequently used routines to load automatically when AutoCAD starts: 

• Open the AppLoad dialog box. 
• Click Contents in the Startup Suite section. 
• Add your .LSP files to the list. 

Now, every time you launch AutoCAD, your routines will load automatically, making it easier to handle tasks in AutoCAD mechanical engineering and AutoCAD 2D drawing for beginners. 

Conclusion 

By mastering AutoLISP routines, you unlock a powerful tool for automating workflows in CAD software. Whether you're a student taking an AutoCAD crash course or a seasoned professional working on mechanical AutoCAD 2D drawings, AutoLISP helps you work smarter, not harder. Stay tuned for more insights in the AutoCAD Essentials for Mechanical Engineers series.  

This blog is part of our ongoing AutoCAD Design Series. If you missed the previous posts, check them out here.  

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