Hi Rogurt, thanks for posting the part, that really helps a lot to figure out what is going on.

Just to help clarify, Steve above is referring to these areas of your model here:



Those are areas where the 2 surfaces come to a shared tangent instead of having a distinct sharp crease. That can definitely be confusing for the filleter, because it's a "disappearing fillet" situation, the fillet between tangent spots is non-existent.

If you want these areas to be all straight like this:



You may want to instead create some larger sweep areas like this or something:




Here's another example to help illustrate what the fillet would be trying to do in your case - here I've built a surface that has a steep angle to the other plane at the sides and in the middle it dips down and gets flatter to the plane approaching that kind of shared tangent situation like you have:



When I put in a fillet there you can see that in areas of shallow angles like that the fillet gets smaller and smaller:



And in your case the shapes are much more tangent to each other than what I show here.

Basically the kind of shaping that you have there creates a sort of anomaly in the fillet right in that middle area.

- Michael

Thanks a lot for explanation. Altered the model accordingly. Filleting now shows but only with ill results :-(
I still wonder why I cant select that edgeloop via the script I mentioned. other loops do get selected just as supposed to.
Tried that "SelectNakedEdges" script maybe to find some sort of insight. But it only shows edges that can be filleted like a charm...

Cheers,
Rogurt

Hi Rogurt, re: select loop - select loop works by selecting edges that are part of the trimming boundary of one surface. It works on some other areas of your model because you've got a big surface in the front here:


In the area that you are asking about there are a bunch of little surfaces and not one big one:




The select loop method only works by selecting a boundary that belongs to one face like the one on the big face, it does not know right now how to cross over edges that belong only to a bunch of little separate faces, that would be a different type of loop traversal method instead of the trimming boundary method that it currently uses.

- Michael

Hi Rogurt, re: new fillet - it looks like the sort of twisting of the loft that you've got there makes a kind of sheared surface that has enough curvature in it to make it so that fillets generated between that and the other piece will not match up and need little corner pieces put in. When the juncture pieces between fillet pieces are tiny and slivery it's another thing that can confuse the fillet mechanism.

If you want to make a regular shape that will be easier to fillet, I'd recommend placing a chamfer on the outer edge, it's the easiest way to make a cleaner shape that won't have that kind of internal curved/sheared type structure to it.

The way you can do that is to have your base block with just the inner cavity removed from it like this:



Then select these:



And apply a chamfer:



This will now fillet much more easily - all the fillet pieces will meet up naturally:





The 3DM file with the chamfered result in it is attached so you can test filleting it yourself as well.

When fillet pieces go between 2 curved surfaces it causes one side of the fillet to extend a bit more along the fillet rails than the other side and then that's what was making your other one a more difficult fillet situation.

- Michael

Hi Rogurt, also see here for some explanation of a similar other situation to your new fillet case:
http://moi3d.com/forum/index.php?webtag=MOI&msg=3557.5

That shows some illustrations on how the fillets between things with differing slopes will not actually align at the same endpoint as the edges - one side of the fillet basically sticks out a ways further than the other side. That's part of what increased the complexity on your particular case - the filleter seems to be messing up trying to deal with the little in between portions that would have needed to be built there.

- Michael

Hi Michael,

thanks for your explanations. Very often I find that it is quite hard for me to find that one correct way to build such a simple model so it will suit for further tweaking.

While I really appreciate that you help us users each and every time, it really takes some time to figure things out this way. In professional application I could not spare that time (the model had to be build in few hours time). A befriended 3d artist mine bought MOI when he saw it on my computer and loved the simplicity but a few weeks later he switched to rhino for exact that "why the heck does the filleting just not work" thing.

Maybe there could be some sort of debug window or colored display of surface curvatures which gives me a clue that there might be a problem. So I´d be able to solve things on my own...

Thanks again,
Rogurt

Hi Rogurt - Filleting is not really Rhino's strong suit either, if more robust filleting is your main concern probably something like SolidWorks or Pro/E would be the choice.


> Maybe there could be some sort of debug window or colored display of surface curvatures which
> gives me a clue that there might be a problem. So I´d be able to solve things on my own...

The problem is that it's pretty unlikely that suddenly flashing a bunch of colors on the screen would make you immediate go "oh, it's the curvature of this surface that is causing the problem"....

- Michael

The only problem I find with MoI is the lack of variable radius filleting. Michael says he is working on it, so we will have it eventually.

As for filleting success, it often depends on the underlying engine. Autodesk have developed there own having broken away from the standard ACIS kernel when Spatial were acquired by Dassault (owner of Solidworks and a Parasolid engine user).

You can get Inventor Fusion for free at the moment. Often it's filleting engine will succeed where MoI's fails particularly where edges join at acute angles.

;)
Inventor Fusion
The Microsoft Windows compatible technology preview executable expires on April 1, 2013.
The Apple OS X compatible version of the technology preview expires on January 1, 2013.

Else you can see this tutorial for complex Fillets inside Moi by MajikMike ;)
http://k4icy.50webs.com/tutorials/Fillet_Using_Sweep_and_Blend.html

I use the built in Error notification/discovery supplied with MoI. If the fillet doesnt work, review the area being filleted. This same mechanism is also used in "professional" environments daily! :o

Maybe if the fillet is difficult, that want to say that the form is not natural and tortured! ;)

At the French Billiard when you must make a "massé" that want to say that your previous play was not optimum ;)

Minute 4.09 - 4.18 :)
This nature of keep the 3 balls along the side of the billiard is called "The american" ;)

@Frenchy Pilou: Many thanks for the tutorial link. This is really good information...

@BurrMan: "I use the built in Error notification/discovery supplied with MoI. " You mean "zooming in and examining", right? Or ist there something I have not discovered yet?

Zooming in and examining is what you do AFTER the fillet errors.