Attached you can find two STEP files exported from the same SolidWorks model.
example_split-periodical-surfaces.STEP is exported with the option “Split periodical surfaces” set.
example_nosplit-periodical-surfaces.STEP is exported with the option “Split periodical surfaces” unset.
The option makes a difference for e.g. cylindrical holes but also for conical surfaces.
Specifically, it automatically exports two half cylindrical surfaces for each full cylindrical surface.
For conical surface we can also see, that they are split in halves.
It seems that GMSH (which is reading STEP files with OpenCascade) cannot mesh the STEP file with no surface split and it generate the error “Impossible to mesh periodic surface” for the conical surfaces.
I'm trying to identify the issue here.
Could it be, that OpenCascade misinterprets the BREP definition for the conical surfaces in the case of example_nosplit-periodical-surfaces.STEP?
Could someone thake a look at this file?