Combine/Join Operation : Sometimes refuses to do it. : What Am I Doing Wrong?

[RogerInHawaii]

On one part of my project I am able to join a number of "shingles" together just fine, using the Combine/Join operation. Each shingle overlaps by about an inch with each adjacent shingle. I get no errors or warnings while doing the Combine/Join operation on these Upper Shingles:

But I'm having a problem with the Middle Shingles. I successfully do a Combine/Join with a few of the overlapping Shingles, but when I attempt to do a Combine/Join between the already-combined shingles and another adjacent/overlapping shingle I get an error.

The overlap looks just like any of the other overlaps. But it reports the error:

Error: There was a problem combining geometry together.
If attempting a Join/Cut/Intersect, try to ensure that the bodies have a clear overlap (problems can occur where faces and edges are nearly coincident).
Failed to Boolean bodies together

I've tried a whole bunch of different approaches with no success. It just refuses to Combine/Join some of the shingles. Several of the shingles are Copy/Paste versions of a master shingle, so I thought that MAYBE it's having trouble with those. But the same situation exists for the Upper Shingles and those combined just fine.

Does anyone have any suggestions?

[jeff_strater]

I'm not surprised that this Combine fails.  To be honest, I'm a little surprised that this is the only one that doesn't fail, if they all overlap like that.  All the places in your image where you can see little bits of the gray body poking through the yellow body indicate the problem:

Those areas indicate geometry which is "nearly identical", but probably not a match down to a very low tolerance.  For instance, those faces might be mis-aligned by 1.0E-6.  But, the modeler has a tough time with that kind of geometry in the Combine logic, especially if the geometry is at all complex.

One approach that might be worth considering:  Take a plane, position it carefully, and split both bodies with the same plane, and Remove the small resulting bodies from both.  This will generate a planar face that both larger bodies have, but which will be guaranteed to be the same.  You may still have issues that result in tiny sliver faces where the edges from each side don't line up exactly, but it might be worth a try.

[RogerInHawaii]

@jeff_strater ,

Thank you so much for that suggestion. I used a slight variation of it to chop off the problem sections of six shingles and then the Combine/Join operations went through without a hitch. Here's my final SOLID BODY which I can now export as STL and get it sent to my 3D printer. Actually, the pic shows the main shingles solidified together as one body and a separate Hatch body.

I have lots and lots of those kinds of overlaps with my numerous shingles and they ALL show those tiny bits of grey showing through, but only a very few result in problems with the Combine/Join operation. In fact, I did a little test, just making a set of cubes. Made a master cube. Made a Copy/PasteNew and shifted it along an axis but left it overlapping the prior one. I did that several times, each time overlapping the prior one. I then individually colored each one with a different color and, lo and behold, there are colors "peeking through" at each overlap.

The Combine/Join problem did seem to happen only (mostly?) when it was dealing with shingles that were Copy/Paste type copies, not Copy/PasteNEW type copies. So, maybe Fusion has a problem with calculating surface interference (or some such thing) when dealing with those kinds of component copies.

Anyway, THANK YOU. You advice always comes through with a solution. I appreciate it muchly.

- Roger Garrett

[chrisplyler]

Spaceship parts are hard. Did you put Fusion 360 into Spaceship mode before modeling this?

[TrippyLighting]

I am on an iPad atm. So cannot confirm, but if I remember correctly, you cannot combine copy/pasted component. But that’s not a  bug but as designed. A copy/paste creates an instance. An instance is just a pointer to the same original data set, which cannot be combined with itself.

[RogerInHawaii]

During my trying numerous approaches to this I had indeed thought that that might be what was causing the problem, but I actually have Combine/Joined the Bodies of Copy/Pasted components successfully.

I have a small target Body and then select the other (Tool) bodies to Combine/Join with  it, and keeping the Tool Bodies. I found that if I have, say, three overlapping instances of a component (each having been created via a Copy/Paste operation) and my Target body overlaps, say, the first one, it fails if I select all three Copy/Pasted bodies at the same time. But if I do a sequence of Combine/Join operations, a separate one for each of the three overlapping instances, it succeeds. So it doesn't seem to like handling more than one overlapping instance at a time.