A symmetric dimension parameter is one which extends from a fixed middle point to two reference points and their respective adjustable point sets. It is comprised of four things: the first reference point, the first reference point’s adjustable point set, the second reference point and the second reference point’s adjustable point set. The fixed middle point is defined as the midpoint between the two reference points when the parameter is defined; the user does not define an anchor point for a symmetric parameter. An example is shown below followed by an explanation of each term.
Reference Points: You will define two reference points. When the value of the dimension parameter is changed, the two reference points move in opposite directions. The distance between the reference points is the value of the dimension parameter.
First Adjustable Point Set: The set of points which move with the first reference point when the value of the dimension parameter is changed.
Second Adjustable Point Set: The set of points which move with the second reference point when the value of the dimension parameter is changed.
To create a symmetric dimension parameter, select Insert - Dimension Parameter - Symmetric, which opens an assistant to guide you through the process.