Auto Cad Basic Commands

📐 AutoCAD Setup for Orthographic Projections

This document outlines the standard steps required to set up an AutoCAD environment and begin drawing orthographic projections from a given isometric view.

Step 1: Initial Setup and Units Configuration

Action	Command/Input	Purpose
Open AutoCAD Software.	N/A	Start application.
Start a new drawing.	Ctrl+N or Select "New"	Open a blank workspace.
Enter the Units command.	UNITS	Configure measurement standards.
Press Enter.	Enter	Open the "Drawing Units" dialog box.
Configure Unit Parameters (Type).	Select Decimal	Sets measurement system.
Configure Unit Parameters (Precision).	Select Precision (e.g., 0.0000)	Defines display accuracy.
Configure Unit Parameters (Units).	Select Units (e.g., Millimeters)	Sets the base unit for the drawing.
Click OK.		Apply the settings.

Step 2: Setting Drawing Limits

The limits define the size of your virtual drawing board (e.g., A4 or A3 sheet size).

Action	Command/Input	Purpose
Enter the Limits command.	LIMITS	Define the maximum drawing area.
Press Enter.	Enter	Start the limits configuration.
Specify lower-left corner.	0,0	Set the origin point.
Specify upper-right corner.	(e.g., 420,297 for A3)	Set the maximum coordinates.
Press Enter.	Enter	Finalize the limits.
Zoom to the limits area.	Z Enter A Enter	View the entire defined drawing area.

Step 3: Drawing the Border and Title Block Area

1. Enter the Rectangle command: REC then Enter.
2. Specify first corner: 0,0.
3. Specify other corner: (Use the same values as the limits, e.g., 420,297).
4. Use the OFFSET and LINE commands to draw the inner border and the title block structure.
5. Use the TEXT (or T) command to add notations, name, scale, and projection type.

Step 4: Drawing the Orthographic Views

Key Tool Settings:

• Ortho Mode (F8): Ensures lines are perfectly horizontal or vertical (essential for projection).
• Object Snap (Osnap, F3): Allows snapping to accurate points (endpoints, midpoints, centers, etc.).

Drawing Process:

1. Set View: Ensure you are in the 2D plane (Model Space).
2. Start Front View: Use the L (Line), C (Circle), and REC commands to draw the primary view based on the dimensions from the isometric figure.
3. Project Top View: Use the L command with **Ortho** enabled to project the width of the Front View upwards. Complete the Top View.
4. Project Side View:
   • Project the height of the Front View horizontally.
   • Use a $45^{\circ}$ construction line to transfer the depth/width dimensions from the Top View to the Side View area.
   • Complete the Side View.
5. Clean Up: Use the TR (Trim) and E (Erase) commands to remove construction lines and excess geometry.
6. Add Dimensions: Use the appropriate dimensioning tools to annotate the final views.
7. Save: Save your work as an AutoCAD Drawing file (Ctrl+S, saves as .DWG format).

Tip on Commands:

L - Line, C - Circle, REC - Rectangle, TR - Trim, E - Erase, O - Offset, T - Text.