Boolean Difference Problem

Hello,
On some surfaces the boolean difference command now creates additional surfaces. I noticed this problem for the first time on the surfaces I created in r8. When I transfer to r7 and repeat the process, I have the same problem again.
Also the same problem occurs when I use the cut handle of gumball in R8
I couldn’t understand what caused this problem, can anyone help?

Here is the r7 file:
Untitled.3dm (55.9 KB)

Same behavior in V4 (after converting the extrusion to a NURBS surface because V4 does not support extrusions).

Hello! From the example you have provided, it appears a split or trim may be a better solution.

Here is a post that covers a bit more on this behavior. Admittedly, the thread here has some tangents, but there is a lot of great info on how / why this might be happening.

Additionally, this post in the wiki explains further - look for the section at the bottom regarding open surfaces.

If this behavior is occurring on closed surfaces / polysurfaces, please post an example and we will certainly look into it.

Hope this helps!

I read the post, let’s talk about Pascal’s example. My opinion is that if the surface is not closed it should behave like example number 1, if it is closed it should behave like example number 2.

Well that’s not how it works. If objects aren’t closed it uses the normal directions–of course that’s what it does with closed objects also!–of the objects to determine which way is “out” and the result you will get.

Booleans are just shortcuts for tirmming and joining, you are overthinking this, it is not a bug. Having booleans only work as booleans on closed objects would make them useless. It seems like you just want the basic split and trim tools here. There is a command called Boolean2Objects that lets you step through all possible combinations until you see the one you like.

I agree this would be the intuitive behaviour.

But strictly speaking, booleans aren’t meant for non-solids.

If this is the logic, there is nothing to do :slight_smile:
By the way, in the file I exported to autocad, this process works as I expected.
I guess i need to change some habits.