Symmetrical Dimension Parameters

A symmetric parameter defines a dimension using two reference points and their respective adjustable point sets. The nominal value of the parameter is the distance between the two reference points. The anchor is defined as the midpoint between the two reference points; the user does not define an anchor point for a symmetric parameter. When the dimension is varied, each point moves relative to the anchor point. When defining your dimension parameter, you perform the following steps:

•    Select the first reference point.
•    Select the adjustable point set that moves with the first reference point.
•   Select the second reference point. The value of the parameter is the distance between the two reference points.
•    Select the adjustable point set that moves with the second reference point.

There is a setting associated with each dimension parameter that determines how the adjustable point sets are moved. With the default, and simplest, option each point set moves one half the distance of the difference between the present value and the previous value out from the middle point, maintaining its relative positive to the reference point with which it is associated. For a discussion of all the options controlling moving adjustable point sets, see Moving Adjustable Point Sets.

Note that the symmetric parameter is always defined as the distance between the reference points in either the X direction or the Y direction, never as a diagonal distance between them.

Two examples of symmetric parameters, each at two different nominal values, are illustrated below. This example uses the default setting for how the adjustable point set moves.