I'm using OpenSCAD to mess up other people's STLs! It works very well until I want to cut part of it away using difference(), but then large parts of the uncut areas disappear in Preview. They're fine when rendered. I've had this problem since I've been using OpenSCAD on every version I've tried, including 2019.05. Is this a bug, a know weakness in the software, or a problem with my computer? This is my latest bit of vandalism, where I've scaled down and assembled various STLs from a model from Thingiverse. I want to cut it in half and mirror it, to make both ends identical. But before I do that I need to cut out some of the inside. The last time I did this, I was able to cut the model up into pieces, save each part as an STL, import it, make the join, and repeat the process, but this time it's not so easy to do that. This is what I'm talking about. This is the model with the cube I want to cut away highlighted: <http://forum.openscad.org/file/t2424/Tram_engine_uncut.png> This is when it's cut: <http://forum.openscad.org/file/t2424/Tram_engine_cut.png> Is there any way to get round this? -- Sent from: http://forum.openscad.org/

Does it show correctly with F6? For a correct preview you need to set convexity in the import statement. On Wed, 12 Jun 2019 at 23:53, JohnB <mail@johnb.me.uk> wrote: > I'm using OpenSCAD to mess up other people's STLs! It works very well > until I > want to cut part of it away using difference(), but then large parts of the > uncut areas disappear in Preview. They're fine when rendered. I've had this > problem since I've been using OpenSCAD on every version I've tried, > including 2019.05. Is this a bug, a know weakness in the software, or a > problem with my computer? > > This is my latest bit of vandalism, where I've scaled down and assembled > various STLs from a model from Thingiverse. I want to cut it in half and > mirror it, to make both ends identical. But before I do that I need to cut > out some of the inside. The last time I did this, I was able to cut the > model up into pieces, save each part as an STL, import it, make the join, > and repeat the process, but this time it's not so easy to do that. > > This is what I'm talking about. This is the model with the cube I want to > cut away highlighted: > <http://forum.openscad.org/file/t2424/Tram_engine_uncut.png> > > This is when it's cut: > <http://forum.openscad.org/file/t2424/Tram_engine_cut.png> > > Is there any way to get round this? > > > > -- > Sent from: http://forum.openscad.org/ > > _______________________________________________ > OpenSCAD mailing list > Discuss@lists.openscad.org > http://lists.openscad.org/mailman/listinfo/discuss_lists.openscad.org >

That makes a huge difference. It's not perfect, but I can work with it. I've set it to 5 here, but increasing it doesn't make any useful difference. F6 is fine, but far too slow to be useful until I need it. Thanks. <http://forum.openscad.org/file/t2424/With_convexity.png> -- Sent from: http://forum.openscad.org/