How to get non-hollow stp files？

[R G W]

Hi everyone, I recently had some problems writing a shape of occ to stp file.
I have an occ solid shape, and then I use the following code to write it to the stp file.

STEPControl_Writer writer;
writer.Transfer(my_solid, STEPControl_ManifoldSolidBrep);
writer.Write("test_solid_target2.step");

My stp file is hollow when it is opened in solidworks, but isn't his type a solid entity type? Where is the problem? I hope you can give me some help, thank you very much.

 

[R G W]

My solid is generated from shell. Using BRepBuilderAPI_MakeSolid, it should be a solid instead of a hollow solid under normal circumstances.
Does this mean that there is something wrong with my shell? How can I detect and fix it?

 

[R G W]

Maybe I can solve the problem. When I set the tolerance of BRepOffsetAPI_Sewing a little larger, such as 1.0, the generated entity is not hollow.
Does this mean my shell is not closed? If so, I have no way to detect him

 

[Quaoar]

You may want to load your initial shape into Analysis Situs and check visually if it has any red edges. If so, such a shape cannot be a valid solid, and that is probably why SW would make it a shell instead. If you recover topology with sewing, make sure to conduct the same visual check afterwards to ensure that the result does not have any naked (open/free/you name it) edges. Other than that, the very fact that you had to increase the tolerance up to 1 mm is not a very good sign as it might indicate some inherent inaccuracy of your model. Feel free to share the initial STEP file for a more in-depth look.

 

[R G W]

You may want to load your initial shape into Analysis Situs and check visually if it has any red edges. If so, such a shape cannot be a valid solid, and that is probably why SW would make it a shell instead. If you recover topology with sewing, make sure to conduct the same visual check afterwards to ensure that the result does not have any naked (open/free/you name it) edges. Other than that, the very fact that you had to increase the tolerance up to 1 mm is not a very good sign as it might indicate some inherent inaccuracy of your model. Feel free to share the initial STEP file for a more in-depth look.

Your suggestion is very helpful, thanks a lot！