Depends on what type of fillets are needed . Fillets in Rhino are generally exactly circular in cross-section which may be correct depending on manufactuing system used. G1 continuity is inherent between a circular surface and an arbitrary surface. (Degree 2 is used because circular arcs can be represented exactly by a degree 2 rational NURBS).
FilletSrf in WIP/V7 now has the option of G2 blends in place of a circular fillets. Rhinoceros Help? Updated: BlendEdge is the G2 blend equivalent of FilletEge and VariableBlendSrf is the G2 blend equivalent of VariableFilletSrf
What is acceptable or unacceptable depends on the application and preferences of the user. Unequal spacing of control point is not always inherently bad. For many engineering applications changes to the shape of a surface are very undesirable/unacceptable. For aesthetic design the changes may be fine.
Trimmed surfaces can be Rebuilt in Rhino. Rebuild works on trimmed surface, and if the Retrim option is selected then the rebuilt surface will be trimmed. RebuildUV works on trimmed surfaces but does not currently have a Retrim option, which could be added. InsertKnot and RemoveKnot can also be used on trimmed surfaces, which remain trimmed surfaces.
Yes, slightly adjusted surfaces being acceptable is definitely subjective, for sure. But realistically if you donât have the construction data, and you donât have the original CAD file, and you need to defeature something, you are Going to end up changing things slightly.
And yes, I misspoke. I meant to say âsometimes, you canât rebuild a trimmed surface.â The retrim command doesnât always work. Iâm sure itâs often issues with translation, mixed tolerances from the original CAD, but Rhino only allowing a single tolerance per instance of rhino, or other various things I donât fully understand. I mean, just to test this out, I created a cube. Exploded it and changed the surfaces all to degree 3. Then used control points to manipulate only the center CVâs to deform the box a bit so that a few of the surfaces had compound curvature.
Itâs 6 surfaces. It joined fine, no naked edges. I tried BlendEdge and it failed. I filleted it all evenly and the object turned inside out and ended up with one naked edge. Explode, join again, and itâs back together. Thatâs Very basic example, and I already got the math to break a little. Dealing with imported CAD from solid or proE ends up being much worse.
Ooooh, so in V7, with blendEdge you canât even do the the normal 3 sided boundary. Thatâs good. The only way that really Sort of works if if itâs a patch surface anyway. And those are never quite pretty.
Iâd love to see the ability to control the amount they flow into the adjacent edge blend.
Anyway thatâs killer. Iâll probably end up abandoning regular old fillet edge for the most part.
And yes, it Very much depends on manufacturing. If youâre dealing with Giant fillets, it really doesnât matter. But if youâre doing an interior fillet and itâs really tight, then youâll be limited to the cutting bit for the tool. Granted, those arenât always balls either, so for that kind of thing, youâd likely want a more appropriate CAD modeling package that can take those sorts of things into consideration.
And yes @eobet, that was my thought as well. Although, you Do still have the same number of surfaces that you may with to extend. But realistically, if you model it in Rhino, and have all that, itâs only takes a few seconds, unless you used the Shrink command for some reason.
Fillets in Rhino arenât difficult to break⌠and sadly, it seems that nothing much has changed, even with BlendEdge⌠(but these last posts belong in the Serengeti forum now)âŚ