Boolean operation of two stls with internal shape

[eml3701.ta]

I want to combine two stls with one encompassing part of the other stl. The problem is that, Boolean operation and make solid operation is removing the internal part of the encompassed object. Here is a simplified version of waht i want to do:

I have two stls, 1 sphere and 1 cylinder with part of the cylinder inside the sphere. I want my final stl to not have intersecting faces between the two objects but every other faces such that a watertight geometry is obtained. However all the methods i tried ended up giving me fatal error during Boolean operation or removed the internal structure when Boolean operation was successful or by make solid operation. 

[Anonymous · Accepted solution]

Not sure if I got you right.

You might simply EDIT/Combine both meshes. In this case the surfaces are still intersecting but exported as one STL.

Or

You might EDIT/Duplicate both meshes, run BooleanUnion on one pair and BooleanIntersection on the other pair. Finally EDIT/Combine both results. In this case the surfaces do not intersect any more but aren't welded.

There are two surface regions inside. The region of the cylinder inside the sphere and the region of the sphere inside the cylinder. One can't weld and keep all these surfaces in a single manifold mesh without breaking the rules of mesh representations. This would need more than two faces sharing the same edge > "non manifold edges". If you really need such a non manifold mesh you need to do the boolean union and boolean intersection in some other application which does rigid booleans and export both results as one file to a not indexed format as STL . Loading this STL to MM ANALYSIS/Inspector should show the intersection line's faces in red...

[eml3701.ta · Accepted solution]

@Anonymous Thanks for the reply

I actually tried the two methods you described before posting for help and the second procedure gave me the closest geometry that i wanted but unfortunately it was not watertight. From reading your description of non-manifold edges, indeed the geometry i require will have edges shared by three faces where the cylinder wall meets the sphere wall. So, i guess i have to figure a workaround for my analysis.

[eml3701.ta]

@Anonymous I found a work around by adding some thickness to the protruding part and subsequent Boolean operation and a lot of geometry cleaning that gives a continuous surface. But for a more complicated cases where there needs to be more than one internal regions the non-manifold option can not be avoided. Any pointers for applications that allow rigid body Booleans?

[Anonymous]

Not sure about the new mesh features in Fusion360 and its booleans. Maybe - did not have the time to try it yet.

You might use Blender which doesn't refine the faces at the intersection as MM does. For such rigid booleans also Rhino3D's mesh tools are an option if the poly count isn't too high...

[zbrushartist76]

Should print water tight or use solder gun n pla to seal or glue or silicone idk sounds like other ways to do water tight than mess so far with walls lol

[zbrushartist76]

more one way to skin a cat they say try thinking outside the box sometimes not everything need be printed and can combiind with printed parts that one full part all pla as such use dowels wood rods than print a tube or rod there are alternatives n feel we forget to make use of other ways to complete a project and use something other than just the printer to do it lol