Why boolean union fails joining two closed polysurfaces?

Hello All,

Here I’m going to describe the problem I’ve been encountering for few last days with images and I’m also adding the model file.

I just can’t see why Rhino fails joining two closed solids into one. I need it for structural analysis and after receving warning " Tolerence had to be doubled for Boolean to work" It no more accepts the objects as solid. Also, boolean union fails in my other trials. Hope someone can help.

Please see my image and model.

boofailed.3dm (3.1 MB)

I can’t quite tell, but I think you should rewind to before the “tolerance had to be doubled” message, that may be screwing up any subsequent action, that should be fixed.

To test if booleans should work, when you run Intersect on the objects you need to get closed curves, and here you get open ones. Why…not sure? You’ve got all these objects you want to combine where they mate, and for that to work they need to be PERFECT, the slightest nudged point the wrong way can cause errors that just compound.

Your model is very far from the origin, that may not be helping.

The message is quite literal - it means your parts are slightly out of tolerance, and by raising the absolute tolerance by a factor of 2, it managed to do… something. However, when you can’t do anything else with the object after, it means that something was not all that great. Sometimes it leaves you with a non-manifold object, that is to say there are one or more surfaces “stuck” inside the model that shouldn’t be there, because of the bad operation. Sometimes the edges are simply too far out of tolerance to be useful.

I wrote the above without looking at your file first. Now I will look. OK, it is the second problem. It made a valid closed polysurface, but the edges are out of tolerance. If you explode the object and rebuild the edges, then try to re-join, it will leave you with naked edges here (4):

They are out of tolerance by 0.06 which is a lot, considering the file tolerance is 0.001.

I suspect that your objects weren’t completely coplanar when you tried to union them.

Hi - possibly unrelated, but still…
I see that you are running Rhino 5.8. The latest version of Rhino 5 is 5.14 and has 3 years worth of bug fixes compared to the version that you are running.