The variety of STL-formats seems to be rather large. That's why CAESES/FFW offers a set of exports, successfully tested with a couple of imports of Meshing tools or CFD packages.
Now, it is not only the format which makes a suitable STL file, but also the topology of the facets. CAESES/FFW provides the possibility to choose from two different approaches: Based on an error function and based on the surface parameterization. Since CAESES/FFW is mostly used for complex curved geometries, the error based method is the default one.
To change this, select one or more entries in the list of of surfaces and click the edit icon next to the name (in case of multi selection below the last entry). Then toggle override defaults and the surface parameterization will be used.
In the picture below, the left volute geometry is based on the error based method, while the other displays the parameterization based type.
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