Roger. 

Hi, I have an STL file that I want to print. The first attempt went bad because the object didn't stick to the brim I ordered. This occasionally happens, and I then add a cylinder with say 6 radius and 0.6 height to the corners to make it stick better. The extra material is easy to clip away after printing. So I load this model http://prive.bitwizard.nl/Top_vert_conic_sm_endstop_v3.STL which is a "distributed" version of: https://github.com/brupje/beagle/blob/master/STL/Top_vert_conic_extruder_sm_endstop.STL into openscad with import("Top_vert_conic_extruder_sm_endstop_v3.STL", convexity=5); This views just fine (F5 - Preview), and renders too (F6-render). Then I add one of my cylinders and it suddenly gets errors.... The errors do not give any useful information as to what goes wrong: When I hit "F6 - render", I get: Compiling design (CSG Tree generation)... Rendering Polygon Mesh using CGAL... ERROR: CGAL error in CGAL_Nef_polyhedron3(): CGAL ERROR: assertion violation! Expr: pe_prev->is_border() || !internal::Plane_constructor::get_plane(pe_prev->facet(),pe_prev->facet()->plane()).is_degenerate() File: /usr/include/CGAL/Nef_3/polyhedron_3_to_nef_3.h Line: 251 Geometries in cache: 10 Geometry cache size in bytes: 1389248 in the log window, and many repetitions of: Error !!!!!!!!!!!!!!!!!!!!!!! in the stdout of openscad. For "getting my print job done", it seems the github version is "Better" in some way that it does not cause havoc with openscad. I don't need help finding a workaround for this specific file: the one from github works. A better error message in openscad could help people less seasoned as me in finding a workaround. I still need to print a few objects from that set, so I would like to know WHAT is wrong, and how to fix/avoid it. screenshots at: http://prive.bitwizard.nl/f5.png and http://prive.bitwizard.nl/f6.png Roger. -- ** R.E.Wolff@BitWizard.nl ** http://www.BitWizard.nl/ ** +31-15-2600998 ** ** Delftechpark 26 2628 XH Delft, The Netherlands. KVK: 27239233 ** *-- BitWizard writes Linux device drivers for any device you may have! --* The plan was simple, like my brother-in-law Phil. But unlike Phil, this plan just might work.

On 10/10/2016 12:06 PM, Rogier Wolff wrote: > So I load this model > http://prive.bitwizard.nl/Top_vert_conic_sm_endstop_v3.STL > Looks ok in Blender, but has some Zero-Faces that cause issues in OpenSCAD. The FAQ has some suggestions on how to fix those: https://en.wikibooks.org/wiki/OpenSCAD_User_Manual/FAQ#Why_is_my_imported_STL_file_only_showing_up_with_F5_but_not_F6.3F > in the log window, and many repetitions of: > > Error !!!!!!!!!!!!!!!!!!!!!!! > Those are coming from libCGAL, which usually means some issues in with the model which they did not really know how to handle. > A better error message in openscad could help people less > seasoned as me in finding a workaround. I still need to print > a few objects from that set, so I would like to know WHAT is > wrong, and how to fix/avoid it. > This would be nice, but especially in case of imported STL files, that is not actually OpenSCAD code, but libCGAL, so short of rewriting all that, that's not a lot we can do. What's on the to-do list though is automatic fixing of those zero-face issues which could hopefully reduce the STL import problems quite a lot. ciao, Torsten.