IGES export preferences

[TriFith]

Hi everybody,
first of all, please forgive me if I missed the right section for my question...

I need to export model from FreeCAD to IGS/IGES format, but I nned to set preferences for export to trimmed surface (144),
Is it possible to set somehow? I have checked the Export dialog, or settings and I havem´t found how to set the output format

Thanks for advice and once again I am sorry if I missed the theme

Cheers TriFith

[wmayer]

I think this is not yet implemented in FreeCAD. In the meantime you can use the tool CADExchanger where it is definitely possible.

[Jee-Bee]

on my mac it 11th export format (under flattened SVG)

[quick61]

I think this is not yet implemented in FreeCAD. In the meantime you can use the tool CADExchanger where it is definitely possible.

It isn't? - http://sourceforge.net/p/free-cad/code/ ... 68d827bf2/

Go to Edit > Preferences > Import.Export > IGES tab and make sure the "Enable B-REP mode" is unchecked. Checked is mode 186, unchecked should be mode 144.

Is this not correct, or am I just confused? (It most certainly wouldn't be the first time )

Mark

[wmayer]

I can't remember if B-REP mode means the same, have to read the docs first.

[wmayer]

In the OCC IGES docs it says about BRep mode:

write.iges.brep.mode:
gives the choice of the write mode. You can choose the following write modes:
"Faces" (0): Open CASCADE TopoDS_Faces will be translated into IGES 144 (Trimmed
Surface) entities, no B-Rep entities will be written to the IGES file,

"BRep" (1): Open CASCADE TopoDS_Faces will be translated into IGES 510 (Face)
entities, the IGES file will contain B-Rep entities.

I need to export model from FreeCAD to IGS/IGES format, but I nned to set preferences for export to trimmed surface (144),

This means you have to switch off the BRep mode.

[cbernardo]

In the IGES format "B-REP" (as already said) uses Entity Type 186 (Manifold Solid B-Rep Object) which in turn uses closed shell, face, edge, loop, and vertex (as you would expect from BREP). This is actually not the preferred method since there was never a formal conformance testing for the feature, which I always thought strange since BREP was all the rage in the mid-1970s and the MSBO was in the early IGES specs.

As for Type 144 (trimmed parametric surface), to work well with MCADs the various surfaces of a part should be children of a Type 308 (Subfigure Definition). A subassembly may also be defined using Type 308 with children of Type 408 (Singular Subfigure Instance) which in turn references other parts/subassemblies. I don't know anything about how FreeCAD exports IGES models, but just saying this so if anyone is interested in ensuring other MCADs are happy with the result they can check to make sure this is how things are handled when the model uses Type 144 for surfaces. Also, MCADs generally expect the color to be associated with a specific surface (Type 144) and associating color with the underlying surface or a parent object gives mixed results.