Bracket symbols contain between two and five geometric inputs. To make the symbol as flexible as possible, the graphic inputs should be defined as B-spline curves . The first two of these graphic inputs will serve as the U- and V-axes of the symbol. The graphic inputs must be defined according to the following rules:
-
B-spline curves should be defined using three or four points.
-
The first two B-splines curves forming the U- and V-axes should be much longer than the bracket arm geometry.
-
The first two B-spline curves do not need to share a common endpoint.
-
The first two B-spline curves should not be constrained together.
-
The symbol geometry must be drawn in the (+U,+V) quadrant of the coordinate axes defined by the first two curves.
-
All B-spline curves serving as graphic inputs must be locked at their midpoints.
Inputs go on one of the following layers:
-
Inputs - Used for supports that do not bound the bracket.
-
Trim_By - Used for supports that bound (that is, trim) the bracket.
-
Make either the Inputs or Trim_By layer active.
-
Locate the (0,0) point in the 2D Symbols file by placing a point at (0,0).
The point is easier to find for later reference if you place a small circle centered on the point.
-
Create the first curve approximately parallel to the +X axis, beginning just to the left of the (0,0) point and passing as close as possible to it.
-
Create the next curve approximately parallel to the +Y axis, beginning just below the (0,0) point and passing as close as possible to it.
-
Lock the curves with the Lock command by clicking near each curve's midpoint.
Do not lock the ends of the curves.
-
Delete the (0,0) point and circle created in Step 2.
-
Create all other required support and limit graphical inputs in their approximate positions relative to the U-and V-axis inputs in a manner similar to that previously described in this section.
-
If some of the support curves belong on the other input layer, shift-click to select the curves.
-
Click Change Layer on the Layer toolbar.
-
On the dialog box, select the needed layer (Inputs or Trim_By) and click OK.