Boolean or Proboolean, Original Object Vanishes

[scodavis4605]

I've had this happen a few times; sometimes I've clicked different ways and solved it with other models, but I don't really understand (a) why it is happening or (b) how to solve it.  I really want to understand this problem so that I can fix it myself for future projects.  To create the attached file, I:

1.  Modeled a slice of a tree using Adobe Illustrator, and exported it as a DWG (I attached this exported file as well).

2.  Imported the DWG as a spline, oriented it correctly, adjusted the pivot point, and used the Lathe modifier to make it a three-dimensional object.

In the MAX file, you can see two objects "Outer Tree" and "Inner Tree" on top of each other.  The idea is that I want to use a Boolean modifier to subtract the inner from the outer, so that I'm left with a shell.  But every time I attempt it, as soon as I add the second object, the whole thing disappears from view, and if I try to export it there is no geometry to export.

I've created many models (all for 3d printing) using the Lathe modifer and booleans - sometimes it works, sometimes it doesn't, but I don't understand why.  I would appreciate whatever help anyone can provide, as I want to learn how to understand and fix these issues.  Thank you!

[jibijib]

"sometimes it works, sometimes it doesn't"

You've pretty much summed up each version release of 3D Studio Max.

I've had the same thing with boolean, I don't think there is a fix, it's just something it does sometimes.

[wernienst]

Ok, the problem here arises, because you lathe'd 16 individual shapes instead of 1 which creates 16 open elements. But objects for successful Boolean operations have to be closed - "watertight".

So, first step: select the spline, go to Vertex subobject mode, select all vertices and weld them by a small tolerance, e.g. 0.01. Thus you get one single shape. The add the Lathe modifier. Check Weld Core and uncheck Flip Normals. Also, in my opinion, 512 segments are way to much. Set it to 64 or so. Now both Boolean and ProBoolean ops will work.

But if you want just a hollow tree object, create the outer tree only, then remove the bottom polygon and add a Shell modifier.

[jibijib]

Do you use the Boolean modifier in Max 2023/2024? I no longer use the boolean operation in compound objects (or wherever it is) with this modifier, it seems to work perfectly.

The only time I've had something disappear if the two objects are not fully manifold (ie they have to fully clip with no parts that have no polys).

This would sometimes cause issues: