Help with a complex radiused edge game plan?

[artesmith]

need some help developing a viable game plan for a “half round” feature on a complex 3D surface; fillets always seem to be a challenge and this clearly the most challenging I’ve entertained…

thanks!

Art

[skysurfer]

Any chance you can share the file?
I’m not at computer now but other maybe.

[artesmith]

here’s the Rhino 8 file:

3p250 elliptical horn for Weber 32-36 radiused edge.3dm (469.3 KB)

[Tom_P]

what section do you expect here ? (x)

and here ?

(both screenshots with clipping plane)

[artesmith]

[jim]

@artesmith

need some help developing a viable game plan for a “half round” feature on a complex 3D surface; fillets always seem to be a challenge

A better way than making a solid and then trying to round the edges is to think of this make as to shapes that can be connected by fillets. That makes the problem dead simple.

In rhino9 beta you can connect the half round shape to the horn shape with just two clicks of the mouse. connect_with_fillets.3dm (1.7 MB)

The largest fillet radius that this geometry will support with out eating into the half round shape is about 0.048"

[Tom_P]

not sure if i understood what you are after.
something like this ?
just a fast subd mook-up:

rhino is missing some kind of 3-tangent-Fillet:

Fillet tangent to 3 surfaces (tritangent fillet) command

Hi all, A command I miss sometimes from other CAD softwares and it may be very decisive for me, is the tritangent fillet which in rhino already exists for curves (circle tangent to 3 curves). [imagen] For example in the image above, the valour of the fillet radius along the path will not be constant, because the angle of the patches are not constant with respect to the base, so doing a fillet in one side and another one on the other side, will overlap each other… Is that possible to achieve…

[artesmith]

Jim/Tom_P-

THANKS; outstanding start!! is a variable radius in the cards? how were the radiused corners created? want to be able to implement your lesson on the revised geometry when it’s ready.

Art

[artesmith]

revised geometry. assuming “filletedge” is the choice, I don’t see a way to select the free edge of a surface?

3p250 elliptical horn for Weber 32-36 radiused edge revA.3dm (528.0 KB)

[Lagom]

Use surfaces, not solids; then you can use FilletSrf as explained above.

[Gijs (Gijs de Zwart)]

@Lagom

Use surfaces, not solids; then you can use FilletSrf

FilletSrf works on joined surfaces equally well.

[artesmith]

[Gijs (Gijs de Zwart)]

@artesmith FilletSrf builds fillets between surfaces and doesn’t use any edges. You need to click on two surfaces that are close to each other and near to where you expect the fillet to land.

[Lagom]

Sure, but why join before the part/model is done? When working on surfaces in Alias or Catia, no joining is necessary; and in no industrial/transportation design course I saw the need for trainees to join surfaces.

[artesmith]

Gijs-

Thanks!! looks like I have one more gremlin…

Art

[skysurfer]

@Lagom

Sure, but why join before the part/model is done?

Some people come from Mcad background where not having a closed solid is always the second or less intuitive option.

Working with both option let the user to choose according to his taste.

[Lagom]

Sure, but if you want proper solid modelling, I’d rather use Fusion or Creo. A neither fish nor flesh approach obviously confuses many, judging from a perusal of 10 years of forum posts. Anyway, just my 5 Hryvnia.

[Rhino_Bulgaria (Bobi)]

From my experience, building a fillet surface between a pair of joined surfaces may lead to an unwanted deviation due to the double loose precision used by the “Join” command. The joined surfaces that are not matching 100% precisely typically teceive a slight deviation compared to their original non-joined state.

This also applies to any other tools that rely on using joined surfaces or their common joined edge as an input.

[Gijs (Gijs de Zwart)]

@Lagom

Sure, but why join before the part/model is done?

I just mentioned that FilletSrf does not require single surfaces.
In Rhino 9 WIP having joined tangent pairs of surfaces is beneficial to create chains in two clicks.

@Rhino_Bulgaria

building a fillet surface between a pair of joined surfaces may lead to an unwanted deviation due to the double loose precision used by the “Join” command

FilletSrf does not use any of the edge information stored in the Brep. So I don’t see how a join could mess up a fillet. If you have an example to prove this claim we should log that as a high priority bug.

[Rhino_Bulgaria (Bobi)]

I had these issues with joined surfaces years ago. Since then I use separate surfaces for the modeling process, then join everything at the very end of the work when it’s time to export the model as STEP.