To Stretch Objects by Editing Symmetrical Dimensions (AutoCAD Mechanical Toolset)

Click Annotate tabDimension panel drop-downLinear/Symmetric Stretch. Find
Enter S to select the Symmetric option.
Select the dimension text of the object's symmetrical dimension (1).
Enter a value.
Select the object to stretch and the associated dimension, using crossing window select.
If the selection set contains objects that you do not want the program to stretch, SHIFT-click the objects (2) to remove them from the selection set.
To select more objects for stretching, select them using crossing window select.
Note: The program moves the following objects rather than stretching them:
- objects enclosed completely within the crossing window
- objects selected individually
- objects selected with window select
Press ENTER until the command terminates.

Note:

You must add one dimension defpoint to the selection set when editing that dimension.
To stretch or shrink objects that are not dimensioned:
1. Select the starting point and the endpoint on the object's contour with the pointer to specify the length.
2. Enter a new value.