I have a Blender project here: Lecce
I wish to assemble a set of intersecting cones, into a single shape. After selecting all cones, I try
from the menu Boolean → (Auto Boolean) Union = Blender project crash
from the menu Boolean → (Brush Boolean) Union = unintended result with only one cone left
My OS is Ubuntu 24.04
edit: I add that as a preliminary step I have carefully corrected the normals following this tutorial
edit2: tried with biconical solids, instead of empty conic surfaces, with similar unintended reuslts, only a few cone are left with lots of square “boolean_cutters”
Those cones have way too much resolution for booleans. If I try the same with lower resolution cones, I can get it to work just fine. Booleans are just simply expensive and they are sensitive to topology intersecting in just the wrong way.
For the unintended results, you can always try switching between the exact and fast modes, but there might be nothing that can be done if the geometry is just aligned in a way booleans don’t like. Sometimes, 2 objects can fail, but then succeed after moving them just a little bit.
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There is an other possible way if booleans can’t do it. You could try to finely voxel remesh them together, then decimate the result to a useable polygon count. Though that method is a bit messy, destructive and final.