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Hi Dimitri.

...here I am!

I've used Moi V3.

This is the little video tut.
It's a video of 120 Mb. If you have a slow connection is better for you to download it first rather then watching in streaming.

The video : http://take.ms/ONGa3

This is the final model : http://take.ms/YWaVN

Please read carefully the texts that I've added to the video as a quick description of what I did.

At the end you will find an explanation of the results.

Ciao!

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...and here the pictures and the video of the "zebra analysis" in Rhino V5

As you can see I think that both the original surfaces and the new model I did, are not suitable for manufacturing.


The video : http://take.ms/VyohW





Marco (mkdm)

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Hey Marco, you devoted so much of your time for giving all this so detailed explanation! This was very very helpful! Thank you heartily my friend! : - )

Now as to 'zebra' analysis in Rhino... is there, really, a way of avoiding such surface continuity defects when working with so many filleted edges on a model? What may be the 'key' element, in modeling process, for avoiding such continuity problems in surface flows? Any related hint?

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About ArtForm
I have made a little page about Installation and formats (in French) Maybe you can try the Google translate! :D
http://moiscript.weebly.com/artform.html :)

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Hi Dimitri, so in a case like this where your opening forms a flat silhouette in a 2D view, the way I'd do it is to create that 2D silhouette, extrude it, and trim it against the open edges you have there.

It's usually better though to have created this 2D silhouette right from the start rather than reconstructing it as I'll do here. Maybe you do have it as part of your earlier construction steps, if you do have it just use your original one rather than the extracted one.

To extract it though, I duplicated the open edges by using Ctrl+C / Ctrl+V on them, and Trimmed them using a center line so that looks like this:




Then I moved those over a bit, went to the Top view and squished them down using the edit frame's corner grip until getting "flat snap" (see here for flat snap: http://moi3d.com/forum/index.php?webtag=MOI&msg=3378.4).



Now you can Extrude those out like this:




Now that extrusion can be trimmed against the open edges to remove the excess area and then joined together. Or also a shortcut for a case like this is to select the extrusion and your main object and run Construct > Boolean > Merge, with open surfaces given for inputs the boolean merge command will intersect them and give back any solid volume that is created removing the excess areas automatically. If it gives any problem then use Trim and Join instead, that's sort of the manual way.

Also for selecting all the open edges it's convenient to set up a shortcut key to do that with one keystroke, see here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2



However, often the preferred way to do this kind of thing is to have your 2D silhouette curve created much earlier on as part of the initial design, and have your object created as a solid earlier on as well with some excess material, then use boolean difference to cut the solid with the 2D silhouette. Using boolean difference to cut a solid by a 2D profile curve will automatically leave the imprint of the 2D curve's extrusion in the result.

Hope this helps!

- Michael

Image Attachments:
dimitri_fill1.jpg  dimitri_fill2.jpg  dimitri_fill3.jpg 

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Hi Dimitri, so this might not exactly apply to your specific case since you've got a thin design that might not have so much natural "extended material".

But for many cases instead of building this which then needs to be filled:


Instead build this extended solid and a 2D side profile curve:


Then you use boolean difference to cut the solid with the profile:


That automatically produces the "fill" by the extrusions of the profile curve without needing to do any extra steps:


- Michael

Image Attachments:
dimitri_fill4.jpg  dimitri_fill5.jpg  dimitri_fill6.jpg  dimitri_fill7.jpg 

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Hello Michael!

Very interesting your reminder of the ""flat snap" tool and extrusion (for this kind of scneario).

Thanks a lot!

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Hi Dimitri.
You're welcome!

@You : "...Now as to 'zebra' analysis in Rhino... is there, really, a way of avoiding such surface continuity defects when working with so many filleted edges on a model? What may be the 'key' element, in modeling process, for avoiding such continuity problems in surface flows? Any related hint?.."

Well...what can I say ?
Unfortunately this particular area of Nurbs modelling is one of the hardest. I'm learning too :)
There isn't any thing like "push a button and do the magic".
To get a quality surface with a good and "real" surface continuity, there are really so many things that come into play.

As I said I'm still learning and anyway for thins kind of things I think I'm not the best Moi user around :)
On this forum there are some other power users a lot more experienced than me about this topic.

And of course all we have the excellent help of Michael!

Anyway, keep in mind that when it comes to play with Nurbs modelling, the very first and most important rule is always the same :
STARTING WITH GOOD CURVES PRODUCE GOOD SURFACES :)
All starts there : Good curves.

For that reason, as also Michael said, I suggest you to redo from scratch your model rather then adjust the actual shape.

You will learn a lot here on this forum. You will see :)

Ciao and have a nice day.

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Michael, thanks a lot for all this so precious information amount! It is immensely helpful (I never thought, for example, that someone can do boolean operations with curves -I took for granted that such operations could be done only with solids-). I will try all the methods you mentioned! : - )))

Marco, by asking about a 'key' element in achieving nicely flowing surfaces I just wanted to learn if constructing in a way that does not have the 'zebra' precision could produce problems in 3D printing. I still do wonder why a fully solid object could have shape consistency problems in 3D printing. It seems that it will be necessary to experiment a lot with such printings for having concrete conclusions. I had never made a print to this day but it is time to do some... : - )

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Hi Dimitri.

Well...as I said I don't have almost any "firsthand" experience in that kind of things and I don't have a 3D printer for the moment...

But I think that (maybe) things like Zebra analysis and other kind of more sophisticated tools for checking the "surface continuity", go beyond the simple 3D printing needs.

They come into play especially when it comes to "build" real thing from 3d models, when we talk about real manufacturing.

I suppose that simply talking about 3D printing, at least if we are talking about hobby, you don't have to worry about surface continuity or other things like that.

But, this is only my thoughts, I think that here there are other user that may have true experience of 3d printing.

Ciao!

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I too do not have a 3D printer Marco -they are too expensive yet for owning them easily- but it is not so expensive to order the print of small items. My interest, those days, is in the field of jewellery and I do wonder if the lack of so fine 'zebra' flows could produce defects in the case of jewellery item prototypes. Thanks for your answers however. And, really, it would be good to hear other opinions too regarding those matters. : - )

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Hi Dimitri,

while i'm not a jewellery designer i would say you can safely forget the Zebra Analysis. The best jewellery designs i have seen are done with ZBrush or 3DCoat for example and those are sculpting programs with no CAD precision and analysis features. So you should not worry to much about Zebra analysis in that case, imho. One thing you could do, for example, is once you have a solid uncheck the visibility of edges in MoI so that you have a flat shaded looking model, to see any imperfections.

Well, hopefully someone proofs me not wrong, in this case.

Regards
Stefan

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H Stefan.

@You : "...So you should not worry to much about Zebra analysis in that case, imho..."


I totally agree!

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Thanks Stefan, the same seems to me too... but it is always good to ask. : - )

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Hi Dimitri

@you: the result is not the desired one, the fill is curved in its shape, while the thing I needed is to have a totally flat fill


A flat fill means to have a ring with two sharp edges touching and ...scratching your finger :)
You want this? I think no...maybe you have planned to fillet the flat fill but Moi's filleter is weak in complex situations like this one.
I did a try using Michael's technique and mine,starting with a minimum radius 0.01....so nothing ;)
Instead i did some blends G2 with a low bulge to have sections little bit filleted but also flat ,extract them using isocurves command.

Second solution that allows you to fillet your fill is to draw a line and adding a point in the middle,so move a little the point to get a little arc





This will be the section(red one) of the sweep,we got the rails trimmed like in earlier pictures





Now i'm able to fillet






Why flat fill don't fillet instead a "bulged" fill do? Maybe because the filleter" have more space to eat" :) let's Michael do and explanation



We have something to check surface quality inside Moi:Dino's lighting !
Here i used onyx light,you can see little artifacts on the fill surface







You can have an alternative to flat snap Michael's showed you(best choice):project your curve on a flat plane








M

Image Attachments:
FILL-3.JPG  FILL-4.JPG  FILL-5.JPG  FILL-6.JPG  FILL-7.JPG 

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Ciao Mauro!

@You : "...You can have an alternative to flat snap Michael's showed you(best choice):project your curve on a flat plane..."

Nice trick!!

Thanks.

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Hi Dimitri,

my humble approach, i only used the sweep command with MoI, with paths created from your model
and since i don't know the fillet value you need i included your original without fillets, so that you can
use (in case you like my approach) your own values. I used a 0.25 fillet G2.



Regards
Stefan

Image Attachments:
Bildschirmfoto 2018-02-14 um 20.31.57.png 

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Just checked again and i could fillet without problems up to 0.39 which comes then close to the outer round
edges of the outer surface.

Regards
Stefan

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Thanks all for the so precious help! : - )

Mauro, thanks for your effort but Michael's way is ok, it gives the proper solution for me.

Stefan, how did you use the sweep in that case? I mean how did you menage to make a fully adaptable, to the circular ends of the object, surface by using only sweep? Can you put a screenshot with the sweep profiles and path please?

And now, I do have two other questions: is there a way to make loop selections in Moi? That's to say selecting an edge, giving a command and so selecting automatically all the continuing edges constituting a loop? And, also, is there a way of selecting the exactly identical in shape entities (be them curves, edges, faces or objects) with a 'select similar' kind command?

I am a user of Wings 3D -it is my standard polygon modeling app- and I know how useful are such selection commands. I needed them in Moi too and I did not find something similar. Are there, somewhere hidden in it, some such commands?

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<< is there a way to make loop selections

this one is existing ;)

A very small Script! :)

script:/*Loop selection*/moi.geometryDatabase.selectLoop();

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