Precision Method 1: Snap And Grid

As you can see, the only method we used to precisely specify points in the X,Y plane was to type the coordinates using Dynamic Input. We do this because we cannot depend on the mouse to specify precise points. In order to use the mouse precisely, we have to use tools to control its movement. Snap is the only tool in AutoCAD that can help us control the movement of the mouse. Using the Status Bar, click on the Snap Mode button.

snap mode
Now, move to the Graphical Area and watch the mouse jump to exact points. The Grid will show a grid of points on the screen similar to grid paper, which is used in drawing diagrams (these points are not real points). A Grid on its own is not accurate, but it is a helpful tool to use with Snap. On the Status Bar, click on the Grid button.

grid dislpay
You can now see the points displayed on the screen. If you think the default values for either Snap or Grid do not satisfy your needs, simply right-click one of the two buttons and the following shortcut menu will appear:

Select Settings and the following dialog box will appear:

drafting setting
By default, Snap X spacing and Snap Y spacing are equal; Grid X spacing and Grid Y spacing are also equal. If you want this to continue, make sure that the checkbox Equal X and Y spacing is always checked. 

By default, if you are working with 2D you will only see Grid dots. If you work with 3D, you will see Grid lines; therefore, you must set the Major line spacing.
Also, all of the settings of Grid behavior are meant for 3D drawings. Make sure that Snap type is Grid snap (we will discuss Polar Snap shortly). If you are creating a 2D drawing, then select the Rectangular snap option. If you are creating a 3D drawing, select Isometric snap. If you want Grid to follow Snap, set the two grid values to zero. You can use function keys to turn on both Snap and Grid:
  • F9 = Snap on/off
  • F7 = Grid on/off