Advanced Filleting

Hi rhino community!

I need help in creating this tricky fillet in between these set of surfaces

It should look something like this in the end but i can’t quite get it right

808c6ff70bf9da6e00ce444c28d813be rg570-jb-genesis-japan-hsh-fr-rw-med-3-141512 dsc_0179_47123
I restored the surfaces to where i started the fillet so those of you who would like to give a shot can use their own method and workflow.

Ibanez RG570 Genesis JB.3dm (12.7 MB)

Thanks in advance

Hi Simone - I do not love, exactly, what I did here, but I think a surface arrangement along these lines may be a good way - I am not sure I am interpreting the photos correctly but, something like this.
Ibanez RG570 Genesis JB_Maybe.3dm (341.1 KB)



Hi Pascal thanks!

It’s very close to what i was looking for, i can work with it, but how did you do this?
What comands did you use and what’s your workflow to make this if i mind ask.

Again thanks a lot, very cool!

Ibanez RG570 Genesis JB.3dm (4.4 MB) Hi , I just worked on the area you were trying to do. I used xnurbs in one section. Isn’t there a command called “sandpaper” to solve these ? you just fill and sand and its all done. :crazy_face: — Mark

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Hi Simone - the hard part here is finding that simple cut surface - once that is in the right place (not quite where I expected), then making the narrow transition surfaces is relatively straightforward, although ‘fiddly’. In any case, think in general, when making transition surfaces like this, I would start with the object complete but with hard edges, so to speak, then make the transitions in an organized way. It is hard to work from the transition to find the ‘main’ design surface.


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Simple cut surface uh? By that you mean like this one for example?

Got your workflow though, starting with hard edges first then filletting and counturing. Got it.
I kinda started like that but i couldn’t get the fillet in the narrow conjunction.

I tried to use the simple fillet comand, tried to cut the interested surfaces, create a profile to sweep with the 2 rail sweep, tried to blend surfaces but it was always glitched in someway. Couldn’t get it smooth…

To be more specific, what comands did you use to get such a smooth and almost flawless transition? (especially in that tricky corner)

@markintheozarks sorry i meant to reply to Pascal.

By the way yeah, i wish there was a sandpaper comand too, or even better an auto fillet comand :joy:

Hi Simone - see the attached file - it shows one way to do this with fillets and a single ‘fake’ fillet as a Sweep2 surface. Ibanez RG570 Genesis JBFillets.3dm (897.9 KB)


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Is there any specific order in which you recommend to do these fillets? Any secret rule of thumb or something?

Hello - no secret - FilletSrf a pair of surfaces at a time, then work out what to do at the junctures, as in my example. Keep in mind that the solution may involve a fillet between an existing fillet and one of the input surfaces. I’d not worry too much about trimming until all of the fillet surfaces are in place.


Sorry for replying so late to the thread but before the quarantine thing i was kind of busy.
I think im doing something wrong…I tried to apply your technique to do these fillets by myself but i really can’t get it right. I get some strange results and by this point i don’t know how to fix it.

I also tried the method that i used to do the other fillets on the body of the guitar but i can’t get such a smooth transition like you did.

I’m lost, again

The palm indent for the cutaway surface might be made simpler, with fewer nodes that cause fewer control points in the surface, indicated by all the isocurve indicator lines. That surface might be rebuilt. If it can, the result would be smoother, with possibly fewer filleting problems. If a fillet is meant to run across a whole mess of isocurves or segmented splits, it’s a sign that rough sailing might be ahead. If you are using a Boolean object to remove that, perhaps that could be rebuilt and simplified before it is subtracted.

Sometimes it helps to do solid merge all surfaces. I am not sure that its the case, but sometimes not filleting adjoining surfaces at the same time causes problems.

Some other things that will cause filleting problems:

  • Not filleting edges at the same time, which also might be the issue
  • Too large a fillet
  • Inappropriate fillet type
  • Filleting a surfaces that already have have splits, segments, and split edges–especially if an entire width/length of a surface may be eaten by the fillet
  • Not filleting the adjoining surfaces

Generally, I keep step-wise versions, in layers, in files, when making deceivingly complicated things. Solid bodied guitars can be tricky to model.

Ain’t no curves on a BMW like that. : )

Thanks @Brenda for the advice, surely it’s important that you mentioned how to get a clean surface to make easier some of the later work etc… but i don’t get why i can’t re-create what @pascal did by myself.
He used the file that i made to create the fillets and i don’t get why he was capable to do it and why i’m not, even though i followed exactly what he said using the same identical file project.
I see that some surfaces are not really clean but he managed to pull it off without problem then i try myself and i get all sorts of artifacts and errors. Why? What am i doing wrong? Maybe some settings in Rhino? Even though i never touched those…

Hi Simon, please post what you have so far.


This is what i got so far…
Ibanez RG570 Genesis JB.3dm (12.9 MB)

Hi Simon - take a look at the cut surface in my file a few posts up and yours here - I made mine flow cleanly to the hard corner of the guitar body:
Blue = Mine
Green = hard corner of the guitar body.

Notice also that the isocurves on the blue surface are not so stretched/skewed as on the red one - that is done in the Sweep2 command (as I recall) , Add Slash button. Just one is needed to true up the isos to be less at an angle to the sweep edges.