Hi guys

Can anyone tell me why I can't fillet these edges properly. As you can see from the screen shot it will fillet to some degree but still keeps the sharp edge and does something else funny around it.. I have been playing with this shape for a while now (even though this file has been recently generated) and haven't had this problem with fillets in other areas. I've also united this object after boolean difference to knock out the shape in the dome.

Thanks for help guys

Lang

Hi Lang,

ok, this probably does not help you (since i couldn't fillet it either in MoI) but here's a version done with a fillet
of 0.7 in an very old copy of ViaCAD, which i still keep for just tasks like this.



Regards
Stefan

Oops,

just noticed that you used a fillet of 0.5, so here's the updated vers. attached.

Regards
Stefan

Hi Lang,

> As you can see from the screen shot it will fillet to some degree but still
> keeps the sharp edge and does something else funny around it..

The filleter is getting confused about how to trim the main object after the fillet surfaces have been generated.

When that happens, it still spits out the fillet surface piece by itself so that you might be able to salvage it for something. The weird looking result is when you are seeing the fillet surfaces kind of submerged inside of your original object still intact - if you hide the main object you'll be able to see the fillet surfaces by themselves and see what happened a bit easier.

In this case the fillet may not like the "seam edge" of your scooped out piece:



When you build the sweep it can be a good idea to rotate your generator curve in such a way that the seam edge of the generated surface will be all on the outside part of the swept surface, that way it will eliminate some of those additional edges here.

- Michael

Another thing that can be difficult for filleting is tight bends in the thing being filleted. You've got quite tight bends in both tip areas of that scooped out part, and it looks like the filleter is getting confused when trying to negotiate the tight bend in the top piece and the thing it generates does not quite hug the object right in that corner area, which is why it's having problems trying to trim the object with the fillet outline.

It's kind of 2 things there actually - a tight bend in the shape being filleted and also near the top the scalloped out part approaches fairly close to being tangent to the dome piece, that also tends to confuse the filleter because fillets start to kind of disappear to zero area in places where 2 surfaces are smooth to one another.

- Michael

Thanks Michael

So if I generate the seam curve (which came from the original curve that made the dome and was twisted) but say scale it so it sits on the outside a little would that sort it?

Thanks

Lang

Hi Lang,

> So if I generate the seam curve (which came from the original curve that made the
> dome and was twisted) but say scale it so it sits on the outside a little would that sort it?

It can often help to do that, but in your case here the fillet still gets confused in the top area where you've got both a tight bend in the edge to be filleted and also the scoop comes close to being tangent to the dome. The fillet that is generated right in that top area is malformed and does not hug the surfaces which is why it's having problems with the trimming part.

It's probably possible to use the fillet surfaces that were generated to get most of it in place by trimming other areas of the dome with the fillet other than that little piece in the tip where it was mangled. Then there will be a small hole that you'd have to patch in using some other surface construction technique like doing a sweep there. Do you want me to try to do that? Or does Stefan's already finished filleted results above from ViaCAD give you what you needed here already?

- Michael

Can you provide the model with the 2 objects in it pre-boolean?

Thanks again Michael

Yeah if you want to have a go at it for me that would be great to see what you can come up with too.

As for the ViaCAD version its good to see others doing it using other software but my intention is to get to grips with MoI and I already use C4D but I'm finding MoI much easier to model and much more boolean friendly than C4D.

Thanks again

Lang

Hi BurrMan

Here you go

Thanks

Lang

Hi Lang,
SO what Michael was originally talking about, was keeping the seam edge out of the mix, so it doesnt bother the fillets..

Notice in your file how the seam of the cutter goes into the object.



This will create a seam edge in that inner surface and make the fillet more complex.

Here is a file back. I didnt figure out exactly how you placed the original, but this gives the idea. Notice how the seam edge of this cutter isnt in the object at all. If you cut with this object, you can fillet large values.

This seam of the cutter can be controlled in the originating sweep. It's comming from the circles. Rotate them will move that seam until it is on the outside of the cut.

Hi Lang, I would actually recommend that your easiest course of action for filleting problems is to get ViaCAD to help out in some of these specific instances - ViaCAD does have an overall more robust filleting mechanism in it and so it can be easier to use it to get the job done more easily in situations like this.

Also the ViaCAD 2D/3D edition only costs $100 so it's pretty inexpensive:
http://www.punchcad.com/p-9-viacad-2d3d-v8.aspx

Filleting is an area of quite complex calculations and so it's just not a bad idea to have another tool in the toolbox for handling difficult situations, particularly when it's inexpensive like ViaCAD. Or also check out Autodesk 123D which is actually free.


> Yeah if you want to have a go at it for me that would be
> great to see what you can come up with too.

So first I reconstructed your tube sweep so that it had the seam on the outer part like I described earlier.

Then I did the same fillet that you showed earlier that gives the funny looking result - that result is a set of fillet surfaces that are sitting inside the dome. Hide the dome to see them more clearly:



After doing some experiments with using those surfaces to try and cut the main object I was able to determine that it was a small area at the top of the fillet that was malformed and not properly hugging the outer dome surface that was preventing things from working properly. It's this small piece up here:



So I deleted that little piece, it's basically junk. Now the problem is to get some closed boundaries to make it possible to trim the dome surfaces. I took a look at the fillet surfaces to see if they might extend a bit further than their current ends, and they did, so I untrimmed them (use Edit > Separate to break things into individual surfaces, then select all boundary edges of a surface and hit delete to untrim it and reveal the entire underlying surface), and that gives this result:



So there's only a pretty tiny missing area now, I'm not really sure why the fillet engine decided to stop the fillets right there, it looks like it was doing a good job right up until that spot, maybe it has something in it where it gives up if the fillet cross sections get too tiny or something. Anyway I decided that probably putting in some curve blends would be good enough to make a close enough boundary for trimming.

To do that I duplicated these edges to make stand-alone curves out of them:



Then used Construct > Blend to put in these blend curves here:



Then I used Edit > Trim on the dome, using the edges of the fillets and also those little blend curve pieces as the trimming objects, and doing that I was able to cut away the material of the dome to make room for the fillet to be placed in there. That leaves this little hole (which is in the attached 3DM file still), which can be filled in using Network or Sweep:



So anyway, it's a sequence of pretty advanced surface editing and trimming operations to deal with this kind of stuff, it's far easier to just export an SAT file to ViaCAD and give it a try over there and then import it back into MoI. That's usually something that you wouldn't need to do very often, just in cases where MoI's filleter gets confused, but when you do need to do a fillet tuneup that's actually a lot faster than mastering all these different low level surface modeling and trimming tools that you would otherwise need to use.

- Michael

Wow, thanks to you both, you really know what your doing with this stuff.

I'll be sure to check out ViaCAD now too as didn't realise it was co cheap.

Lang

You have also the free 123D for hard Fillets ;)
http://www.123dapp.com/ Import Export SAT, STEP, IGES
By Zarkow

Hi All

With ViaCAD, I can see on their website that it imports Rhino files , will it out put 3dm file? is it easy to move models between MoI and ViaCAD ? (there does not seem to be a demo I can play with )

Cheers, Stephen

trials Viacad
http://www.punchcadlabs.com/page12/page12.php ;)

Hi Stephen,

> With ViaCAD, I can see on their website that it imports Rhino files , will it out put 3dm file?

The version that I have here which is a couple of years old has a 3DM import but not a 3DM export. But it does export SAT, IGES, and STEP files so you can use any of those formats for transfer back into MoI.


> is it easy to move models between MoI and ViaCAD ? (there does not
> seem to be a demo I can play with )

I've had good results using SAT format for going from MoI into ViaCAD, then probably use STEP format for the return trip back.

- Michael

>With ViaCAD, I can see on their website that it imports Rhino files , will it out put 3dm file? is it easy to move models between MoI and ViaCAD ? (there does not seem to be a demo I can play with )

3dm import does not work except if you plan to import basic shapes. .SAT is the way to go.





But is worth the $100 for me that I often need to bring DXF/DWG into MoI :)

Incidentally. the original file supplied in post 1 filleted perfectly in Inventor Fusion, with a 1cm fillet.