Hey Michael,

I'm getting a frustrating boolean issue with a model I just started. I've attached the model and a screengrab to help describe the issue.

I'm trying to do a difference on the central object, removing the "vanes" highlighted in the screengrab from the central object. But every time I try, nothing happens - MoI doesn't even display the "calculating" flag on the dialog box at the top of the GUI . What am I doing wrong?

BTW - the central object was made from a revolved curve - not sure if that would impact what I'm trying to do.

Let me know if you need system specs or anything like that. Any and all help you can provide is greatly appreciated.

For any reason you round object has something wrong
So select all round pieces Separate
select all round piece Boolean Union

Then you will make any bolean operations :)

Hi Satoribomb, the central object looks fine.

One area that tends to be difficult to calcualte is stuff involving coincident surfaces - this is when parts of the cutting object runs right along parts of the base object instead of punching through it. For example in this case this area here:



Ideally that wouldn't matter, but it does tend to be an area of complex calculations and sometimes if a boolean is failing you may have to avoid this type of a cut where surfaces are hugging right along each other.

For a workaround in this case, I used Edit/Separate to break your central hub into different surfaces, and then joined just the parts that will actually be cut into their own object, capped it with Construct / Planar, and then booleaned that sub assembly. This worked for all but one of your flanges, one still will not boolean even then.

So I took a closer look at your flange, and it has a kind of messy area in it at one tip:





There is a little tiny extra slivery surface running right along one edge. It is really small - these kinds of little tiny slivers tend to throw a monkey wrench into booleans as well. So that may need to be repaired somehow before the boolean will work completely, maybe just hack off a little bit of the back or something?

Anyway, those 2 issues seem to be what are causing your problems in this case. Let me know if you need any additional help tuning these up.

- Michael

Michael & Frenchy,

Thanks for the feedback and assistance. I tried Michael's approach - separating the central object and hiding the coincident sections. Worked like a charm.

Also, part of the difficulty and complexity of the vanes' surfaces is that I did a boolean diff on the vanes first, to make sure the curve of the central object was preserved after removing their volume from the central object. This still seems to be a sticking point - I'm finding a lot of micro surfaces and edges I have to clean up, but at least I'm getting closer to where I intended.

Thanks again to the both of you. This community is yet another reason I'm saving my pennies to buy a seat of MoI.

Hi Satoribomb,

I see now where that particular micro edge/surface came from. Your flange box ended right at a spot creating this kind of a situation between a box and a circular piece:



It's that type of a relation that caused those little slivers in this case.

Often times it is difficult to guarantee that different pieces meet up in a simple way. That's one reason why it is often times a good idea to generally make boolean pieces overshoot each other by a fair margin instead of having cutting pieces try to match exact lengths.

I guess applying that advice to this particular situation would mean extending your flanges like this:



To do that, I extended the box until it was sort of completely poking out through everything on that side. This avoids the micro edges, and the boolean will succeed:



However, you can notice that the coincident/overlapping areas that I showed in red in that earlier post have sort of left some of their edges behind. This is hard to avoid, when there are overlapping pieces it is difficult for MoI to always produce the optimal result that you would like, sometimes different edges of all the pieces will get incorporated into the final result. So to make a really clean result I would still recommend extracting out that central section and doing the cut just on that and then recombining pieces later. Avoiding the overlapping areas just tends to guarantee you cleaner results.

- Michael

One work-around that some people use for objects that won't Boolean because of coincendental
surfaces is to either scale or move one of the objects by 1.005 or so before you do the Boolean,
which positions the surfaces out of tolerance just enough, so that MoI knows which surface goes where. Usually scaling one of them works, but if it's a stubborn one, you might have to move it, too. I had one like that last week that was killing me, so I finally gave up on trying to fix my model and moved one object by .005, and boom, it Booleaned like a champ! When you're modeling for production, you can't always afford to model with "elegance" but to just get the job done. :-) It will look the same to everyone, but you. :-) For jewelry design, it makes no difference in the finished prototype, but I guess for some industries, it could mess things up.
If you try scaling the torpedo in your model by 1.001, the Boolean will work.

-Jesse

Edit: I should add that Michael's approach is the preferred one. The scale/move technique is sort of hack that would be better to use as a last step after all your other modeling work is done.

< completely poking out through everything on that side.
that makes completely sens :)