On Sat, 12 Sep 2026 19:33:04 -0700, you wrote: >On 9/12/2026 3:22 PM, Terry Pinnell wrote: >> Have you tried it yet on your presumably modern version of OpenSCAD? > >Same problem.  I'm not an expert at analyzing bad STLs.  I didn't see >any problems, but I handed it to a couple of online STL checkers and >they said that it has several holes, several backwards faces, and >several degenerate faces. > >Ask Mr. Google for "STL checker". > >> I'm not sure I understand what you mean. Various 'issues' have arisen as I've worked on it throughout today. But the core task is clear enough: getting the STL into shape so that my code will work. > >What I meant was that you were encountering two distinct problems. > >The convexity problem manifests as parts - in this case large parts - of >the model being transparent.  That is, as the AI said, a preview >problem, but it can be quite disconcerting.  It's also pretty easy to >diagnose and address. > >The topology problem - that the faces don't fit together right - is >harder to diagnose and fix.  Easiest is probably to find a >check-and-repair tool and let it do the repair, then inspect to make >sure it didn't do anything bad.  In theory you could find the bad faces >manually and repair them manually, but it wouldn't be fun. > > >You should probably upgrade to a recent build, but as I said it won't >solve this problem.  My recommendations at this point would be to either >track down a check/repair tool, or ask on the mailing list (making it >clear that you've addressed the convexity problem and that you're >encountering CGAL and Manifold problems), or just reverse engineer the >part and recreate it using OpenSCAD. Thanks, understood. I did investigate several repair tools. Including several AI agents' apparent favourite, 3D Builder, which was withdrawn over two years ago! And Prura's 'Netfabb'. And Autodesk, etc. Still looking but all those returned a result from my code that showed an empty screen. Typical message in OpenSCAD: "The given mesh is not closed! Unable to convert to > > CGAL_Nef_Polyhedron." Despite what I said about hating unsolved puzzles, there are limits! I'll use my Dremel. But if this is down to OpenSCAD being extraordinarily intolerant that's worrying, as I expect to be downloading more small functional parts for minor edits. "ask on the mailing list.." Sorry, my mistake, I carelessly assumed my subsequent posts after the original *were* going to the list. I'll cc this one. Terry