Boolean union on this intersecting simple solid fails..why?

I have intersecting solids, formed from separate offsetSrf commands, yesterday A and B union, then B & C fail.
…but today A and B fail whilst B to C union ok ! I havent moved them at all .

what is going on ?

D and E fail, yet they intersect. Move E fwd a bit and boolean works.but then its not touching the brown object.

Could someone explain why what appears to be two solids one inside the other fail ?

They intersect, they are ok for Dir,

surfaces were offsetSrf3mm solid=yes. from the surfaces of the brown object.

layer in red has the intersecting surfaces used to cut the shape from the brown object.
Boolean fail on intersecting solids.3dm (397.3 KB)

Minimagic will show union fail areas I am told.

netfabb will repair.

Ideally its best to see and fix in Rhino, though www says Rhino Booleans are known for this. Is that so ?

It also says that such when opened into rhino 4 will boolean when v5 fail, I just tried that and yes !!! no problem.

I have spent ages when V4 wouldnt have caused this.

Boolean fail on intersecting solids rhino4.3dm (386.6 KB)


Why do you need to boolean these objects? Why not just generate curves and create this as a solid to begin with? You could boolean the large object with a polysurface. It’s impossible for Rhino (or any other Cad package) to generate a clean solid from these objects. I managed to get A-B to union and used merge all faces then exploded it and it’s a complete mess. Just look at the confusing overlaps and sliver points.

Stratosfear is right - Booleans are not the right tool to use for this job. When you have all this stuff that overlaps like this, you’re just asking for trouble by using Booleans. (and he’s right, regardless of CAD program). This is very simple shape to model, no reason to get Booleans involved, and plenty of reasons not to.

The fact that it was simple I went for a quick route or so I thought to get the solids 3mm thick on face of the brown wall and fuse them. wall not being 90 deg is deliberate, tail mustn’t wag the dog. wall must be that angle. brown object is pure, not a mess.
so mess comes with offsetSrf solids being at also that angle and the slivers…offsetSrf creates solid, then union them, seemed quick.Life cant always be 90deg etc. If I move E fwd a whisker, it booleans.

What i want to know though is V4 WILL UNION THESE, V5 fails. how become ?
posters on internet comment on V5 v V4 and having issues now when they didnt before.

I will have to hand construct such as you say where it is simple as this. Trouble is complex parts dont boolean, because they are complex, well for me anyway.


I would be more upset that Rhino will boolean these objects at all. The completed booleans have internal surfaces and are a complete mess.

Your problem is not with the tools or complexity of your objects. It has everything to do with your refusal to use (learn) the correct tools (commands) and modeling techniques. I will also add the correct sequences like with your fillets.

It’s like you’re trying to eat soup with a fork. There is a reason why companies want certified modelers. You’re expending a huge amount of time and effort posting on this forum that would be better spent learning the basics. Cad packages are not designed to bend to your will or adapt to your approach.

Okay, so the goal here is to take that MDF piece, and make a 3mm offset of it right? So, to start with, Boolean is not the right way to do this. The way you are approaching the modeling is what is causing your problems. This is not what Boolean is used for. And, as stratosfear has pointed out, you’ve got all sorts of weird overlapping issues that will just make a mess of your surface. Also, your surface is made up of far more surfaces than is needed. By my math you only need 10 surfaces to describe this object. You’ve got 29. This is how quick and easy it is to make a “clean” version of your surface:

I used the DupEdge command to grab all the relevant surface edges.
I used Rebuild on all of them at once, and set it to degree 5 points =7. The max deviation was something like .002 mm.
I then used Loft with it set to Straight Sections to create all the surfaces except the end caps.
I joined the surfaces with Join.
I ran Cap to create a closed solid. Cap is a nice check too - it won’t work unless the openings are planar.

Lest you think doing it right takes longer, I timed myself. 2 minutes 29 seconds.

Now, to create your 3mm offset, I copied the object, and exploded it. I then joined the surfaces that were to be offset, using Join.
I ran OffsetSrf with it set to 3mm, accuracy to 0.01, and corners set to Sharp, no Solid.
I used MatchSrf to make the outside sides of the object match up to the top surfaces.
I joined the surfaces, and then ran Cap.
Cap did not work, since the opening was no longer planar, due to the offset.
There are two ways you can solve this. One is to extend the surfaces and then trim. The other is to simply edit the points along the opening so that they are planar. Since they were very very close to planar, I opted for the latter. I exploded the surfaces, turned the points on and used SetPt to make the opening planar. Turned points off, joined the surfaces with Join.
Ran Cap and it closed perfectly.
2 minutes, 49 seconds.

I’m writing this out to show you that there are totally different ways of working in Rhino from what you’re doing. This is the easy way to do stuff.

The way the meshes are interacting on this tells me from experience these surfaces are for all intents and purposes identical.

Boolean fail on intersecting solids_SkyG_Version.3dm (599.8 KB)