Combine/Joint results in "Loop containment cannot be determined" error

[RogerInHawaii]

I've got a Body with several other Bodies that intersect with it. I attempt to do a Combine/Join operation, selecting the main Body as the Target and the other Bodies as the Tools, but it pops up an error: "Loop containment cannot be determined". I narrowed it down to one particular Body that causes the error, but it sure looks like all the others. In fact all of those Tool Bodies are IDENTICAL since they are from identical Copy/Pasted Components.  Each one is Jointed into a prepared hole in the Target Body.

What is that error message actually telling me and how do I fix it?

[Beyondforce]

Hey @RogerInHawaii ,

Will you please attach the file!?

Cheers / Ben
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[RogerInHawaii]

My project is too large. Its size exceeds the limits for attached files.

Can you give me some idea of what the error message means?

I'm considering just deleting that individual component that causes the error, Copy/Pasting and Jointing a new one to see if that fixes the problem. But it would be nice to at least know what the message means.

[Beyondforce]

Do all the bodies that you have just combined inside the same component?

[TrippyLighting]

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@RogerInHawaii wrote:

. But it would be nice to at least know what the message means.

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I'd be interested to hear what @jeff_strater will have to say, but I think this message comes from ASM (Autodesk Shape Manager), the geometric modeling kernel employed in Fusion 360 and Autodesk Inventor.

Solid Modeling techniques such as boolean combines under the hood require the kernel to break this down into trimming and stitching of surfaces.

What the kernel can't determine is "the containment" of such a trimming loop". It would be easier to demonstrate if Fusion 360 had an "untrim" command.

You could try to work with surfaces here and do this boolean combine manually.

[RogerInHawaii]

All four of the Bolt/Washers are contained within the same "Bolts & Rivets" Component, which is a sub-component of the overall "Crew Cabin Middle Shingle B7 LiftRingCover". Both 1275 and 1276 are positioned using a Joint operation, Jointing between the circular bottom of the shaft of the bolt and the circular bottom of a prepared hole in the parent Body. The others are positioned using a Circular Pattern operation. Each of the Bolt/Washers are identical and consist of a single Body. The shaft of each one is actually larger in diameter than the hole into which it is inserted and the washer is thicker than necessary so that when positioned the bottom of the washer is lower than the curved surface on which it resides. The reason for these two "bigger than expected" sizes is so that when the boolean join is done it's assured that the result is all one, nice, solid Body with no gaps. This helps to assure that when I do a later "Save To STL" it avoids errors in the Meshmixer.

So, bottom line, all of the Bolt/Washers ought to do the boolean join just fine. Plus, I've done this type of join a hundred times previously with many, many Bolt/washer and never encountered this error.

[laughingcreek]

just for fun , what does a cross-section analysis through the middle of the bolt look like?

It can help to break things down and isolate problems.  have you tried to save out just the 2 bodies in question and combine those?

[TrippyLighting]

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@RogerInHawaii wrote:

My project is too large. Its size exceeds the limits for attached files.

Can you give me some idea of what the error message means?

---

You could always share a public link to it even per PM if needed. But the real reason for this reply is this:

I don't own a 3D printer but the consensus here on this forum has been that geometry does not have to be combine in oder to be 3D printed. For the most part the slicer software will take care of this.

With that in mind for much of the geometry in your designs it is better to create instances of geometry buy copy/pasting or patterning. Rather than say pattern bodies. In such a detailed design that can grow a design very quickly. That is particularly true for a design with an enabled timeline.

Timeline designs are approximately 3 times the size than DM designs.

[RogerInHawaii]

The Section Analysis idea is a great approach. I didn't try that but I did display the design in wireframe mode and carefully examined the area where the problem was occurring and, lo and behold, there was an inadvertent void behind the end of the bolt. I deleted the bolt as well as the hole that it was Jointed into, recreated the hole, made a new instance of the bolt, Jointed it in, and the error went away.

I don't know why a void would cause the problem with the combine/join operation that I was seeing. Surely there are combine/join operations where the INTENT is to have some internal empty space.

As in many other cases where Fusion reports a warning or error the message itself rarely provides enough information to understand what actually is wrong and how to correct it. It would be so helpful if Fusion were to somehow highlight the problem area and better describe why it's having trouble with the operation.

[RogerInHawaii]

I don't own a 3D printer but the consensus here on this forum has been that geometry does not have to be combine in order to be 3D printed. For the most part the slicer software will take care of this.

My experience has been that the "Save to STL" function just does not do a very good job of creating the STL file, ending up with one that has lots and lots of errors that are detected by the slicer, or at least by Meshmixer. I did a bunch of testing (prior to buying my own printer), trying to fix things with Meshmixer and/or slicers, and then uploading them to 3D printing services, only to have those services say that the file is not printable.

So my approach has been to Save To STL, see what Meshmixer thinks of it, and then go back to the Fusion file and try to make changes that will result in no, or at least fewer, errors in the created STL file. Even then, there have been STL errors which, when "fixed" by Meshmixer, ends up creating a horribly disfigured model.

So my best approach has been to try to SOLID-ify the model in Fusion via the Combine/Join tool so that each part that I want to send out for printing is a single Body. So far that approach has been pretty successful and I've actually been able to make some prints. 

With that in mind for much of the geometry in your designs it is better to create instances of geometry buy copy/pasting or patterning. Rather than say pattern bodies. In such a detailed design that can grow a design very quickly. That is particularly true for a design with an enabled timeline.

Timeline designs are approximately 3 times the size than DM designs.

I am indeed creating instances of and patterning Components. I am not patterning Bodies.

As for having the timeline enabled, that has been absolutely crucial in creating my overall design. There is no way that I could have developed this and done the necessary editing to it if it had been done in Direct Modelling mode, especially since this is the first significantly complex design that I've done. Everything prior to this was just small projects. Fusion 360 is the first 3D modelling software that I've ever used. So I'm definitely still in learning mode.