Problem Subtracting

In the attached, I am trying to boolean subtract the blue from the red. But I keep getting subtraction failed
Subtract.3dm (690.6 KB)

When I do an intersect on the closed surfaces I get closed ovals:

I don’t see naked edges or manifold edges. SelectBadObjects gives nothing. So I am wondering what the problem is?

And for you folks who joke about my oversized models (not finished yet):

i am not 100% positive on it yet but i suspect that the walls are not equally thick of that tone whatever that is, its also thin enough that boolean might just fail there. if you use the intersect curve you can trim a hole right through it with one click. that should not happen… maybe rebuild that surface again maybe a tiny wee litte thicker.

ah and put those guns away, maybe replace it with a pool :wink:

Hi Jim - the little bow-tie thingy has a surface in it that is basically a line - much skinnier than tolerance - I’d remake that object more cleanly.


Subtract 2.3dm (70.0 KB)
Here is the shape of the opening I am trying to create (layer 1) and the object I am trying to subtract from (layer 2).

What would be the preferred method of creating the shape?

Hi Jim - is the small object meant to be symmetrical?


The ovals should be symmetrical.

OK, well it is out of whack and I cannot tell what the intention is - as far as I can see the centers of the shapes are not all falling on a line and the planes of the curves are not quite parallel. I’d get all that sorted out and build this thing cleanly. That said, Loft is behaving very strangely on some of the curves… digging into that.

I just remade the curves - works fine…

Subtract _PG2.3dm (109.6 KB)


Yes, the planes are not parallel.