Assign Symmetry Lines
In addition to the reference elements, the configuration of this part suggests that it would be useful to assign symmetry line constraints to the centerlines of the elements that we're going to be resizing.
1. In the Generate Constraints dialog box, click the Assign radio button. Then pull down the Type selection list and select Symmline.
2. Click Apply.
3. Click on each of the four centerlines that run through the holes in the two views. The figure,
Manually Assigned Constraints shows the placement of these constraints.
4. Click End.