To achieve the tolerance required by solid modeling, it is important to manage the modeling units and tolerances when creating your model. The millimeter (mm) or inch is generally used as the base linear unit. Standards for tolerances have been developed as they apply to engineering-based CAD systems.
If you are not sure of the standards your companies or clients use, ask your CAD system manager. Set up your units and tolerances at the beginning of your modeling session and save them as a preset in the Construction Options box. The next time Alias is opened, the preset that was in use when Alias was last exited, will be in effect.
To join or align surfaces successfully in the target system, the gap between the surfaces of your model must be less than the accuracy defined within the solid modeler.
Rational and non-rational geometry concerns for data transfer
In the Preferences > Construction Options window, you can specify whether the new geometry being created will contain the rational or non-rational component.
Rational geometry contains CVs that do not have a uniform weight, while the CVs of non-rational geometry all have the same weight. Some CAD systems that do not support rational geometry rebuild the rational element of geometry upon import. This changes the intended design and therefore you should know ahead of time whether the target CAD system supports rational geometry.
Rational fillets are created with fewer isoparametric curves and the tangency to the adjacent surface can be up to ten times more accurate. While this is an advantage in Alias, it is even more apparent when the geometry has been transferred to a solid modeler. The closer adjacent surfaces are to exact tangency, the more usable the imported Alias data is in downstream operations. For example, the further the geometry can be offset during the thickening operation.
Once the above conditions have been met, try several sample translations to verify that the geometry is being passed from Alias successfully. Before modeling a project in Alias that is intended for export, model several sample pieces of geometry in mock modeling situations, then transfer them and attempt the stitching operation in the target CADS system. This will confirm that the model, when completed, will transfer successfully.
Whether you are creating a model, verifying a model, or debugging a translation, there are a number of tools in Alias you can use to check the quality of the geometry you have created. The most useful tools are the surface continuity checker
(Evaluate > Continuity > Surface Continuity
) and the Min/Max measurement tools (Locators > Deviation). Use these tools to check the maximum distance between surface boundaries in Alias to confirm the integrity of the model before transferring it to the target CAD system.