All local operations, including tweak, move, taper, shell, offset, and sweepmore, are tolerant modeling friendly. This means that local operations behave sensibly when tolerant geometry is encountered. (The tweak algorithm is the foundation for all other local operations.)


When nontolerant edge geometry does not lie on adjacent faces to within
SPAresabs (indicating a failure earlier in the operation), the edge can be made tolerant to allow the operation to finish. In these cases a tolerant edge is only created when the tolerance will be less than 100.0 *
SPAresabs.


When an edge tangent to
ACIS tolerance whose geometry is not a line is found between a plane and a cone, the edge is made tolerant and a straight is substituted for the edge geometry. (Mathematically it is easy to prove tangent intersection curves between planes and cones must be lines. Using this fact, local operations is able to simplify model geometry and speed the operation.) Imported data shows this problem where planes and cones do not quite line up.


Nontangent tolerant edges (or tolerant edges that become nontangent or nonnear tangent in the local operation) are reverted to ordinary edges by using the precise geometry from the intersection of the edge's adjacent surfaces, as shown in Figures 62 and 63.




Figure 62. Before face is moved




Figure 63. Lateral tolerant edge reverted to ordinary geometry


When a vertex position cannot be determined, the vertex is made tolerant and the operation is repeated before the local operation is allowed to fail.
