Boolean Difference random error

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 From:  SadgaS
8472.1 
Hi!
At first I need to say that I'm a newie on this software, I work as concept designer/modeler and I'm familiar with other software packages.
I have search any similar thread without results, if it exists would be great to have the link here ;)
I'm having some random error with boolean difference, doing the same operation as you can see in the attachment.
I'm using the same resource to create surface details, and doing the same operation that worked some steps ago(with the same objects) it doesn't work after.
I've tried to boolean diff with simpler source objects and looks like the big geometry(the one I'm adding surface details) doesn't allow to do anymore boolean diff operations(diff only creates holes where I can see inside geometry).
Sorry about my crappy english :S

EDITED: 15 Jun by SADGAS

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 From:  bemfarmer
8472.2 In reply to 8472.1 
For help, please post .3dm file.
Is object a solid?
- Brian
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 From:  SadgaS
8472.3 In reply to 8472.2 
I think it is solid, but I don't know how to check it in Moi, if there is a way to do it.
I have upload the file, blue objects(B) would be details to diff in the big regular gray/white one(A)
Thanks for the help

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 From:  bemfarmer
8472.4 In reply to 8472.3 
In the upper left corner of the screen, the large body shows as joined surface (srfs), rather than solid.

I unioned the two blue "triangles" with the large body, then hid them. The indentations seem to be proper.
(Still not a solid.)
- Brian
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 From:  Frenchy Pilou (PILOU)
8472.5 
Like this but have yet a such complex spaceship as solid must be beverified from the beginning at each step!
Maybe it's too late for make an only one solid...or some hard!



...and delete the original and move the right front faces result on the ship! :)

with the free SimLab Composer Lite (max 1920 *1080)

EDITED: 15 Jun by PILOU

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 From:  SadgaS
8472.6 In reply to 8472.4 
Thank you, it worked!
I'm reading some posts about the joined surfaces and solids right now to keep it for future stuff, basically I want to find a way to discover were is it opened and if possible to turn it into solid.

It's weird to use union to obtain same difference's result, is this some kind of dark maneuver or it has an explanation?

Thanks again for the quick answer.
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 From:  Frenchy Pilou (PILOU)
8472.7 In reply to 8472.6 
Before Michael explanation :
Boolean Union is more for Volumes (in 3D)
Join is more for 3D Surfaces

and if all surfaces are "waterproof" you will obtain a "Solid" with Join! :)
So normally you will continue to do boolean operations like above wanted without difficulties!

EDITED: 15 Jun by PILOU

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 From:  SadgaS
8472.8 In reply to 8472.7 
Thanks Pilou,
I understand :)
I'm making the regular newie mistakes, but as always there is a first time for everything!
I'm most a poly to poly 3d modeler and this is my first experience in 'cad' stuff, this is my 2nd model in moi trying and learning stuff, but damn, it's fun as hell!!

I'll post some renders when finished,
Thanks guys!
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 From:  Michael Gibson
8472.9 In reply to 8472.6 
Hi Sagda, yes so like Pilou mentioned that boolean behavior is because the object isn't a closed solid. The booleans determine which pieces of objects to keep and which to discard based on what solid volume they are contained inside of. When the objects aren't solids that method can't be used and instead it work more like surface trimming.

There is a script you can set up which will highlight naked edges (edges that are not joined between 2 faces) here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=2798.6

In your case here though it's hard to find them because they are very small and spread out in 3 areas:







It looks like it was probably caused by filleting having some difficulty in that spot. Probably the reason for filleting having difficulty there is the surfaces here aren't quite tangent to each other:








Things that are nearly smooth like that but off by just a few degrees tends to make things difficult for filleting. That's because if surfaces meet smoothly then the fillets generated along them will also meet smoothly but if there is a crease between surfaces, the fillet pieces don't naturally end and they have to be trimmed against each other and possibly a corner juncture patch put in, but these things are difficult to calculate when the angle deviation is very small.

It should probably be feasible to repair your object and get rid of the naked edges by some strategic untrimming and retrimming, I'll give that a try.

Also there are some tips for people coming from a poly modeling background here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4865.2

- Michael

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 From:  Michael Gibson
8472.10 In reply to 8472.8 
Hi Sagda, here is a version of your object that has been repaired to get rid of those 3 little unjoined edges to make it back into a solid. Booleans should now behave as expected again on this one.

So one thing to watch out for is try not to make curves that are almost tangent to each other but only off by a few degrees. That kind of very shallow crease will tend to make it difficult to fillet later on.

- Michael

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 From:  SadgaS
8472.11 In reply to 8472.10 
Hi Michael,
thanks for the explanation, fixed file and the links(this is gold for me at this learning steps), I'm having a lot of fun learning to use moi and I really love how easy to do is some stuff in terms of just create the concept.
Have a great weekend!

EDITED: 16 Jun by SADGAS

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 From:  Michael Gibson
8472.12 In reply to 8472.11 
You're welcome Sadga and I'm glad you're having fun with MoI!

- Michael
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