I’m modeling this to 3D print. First image is before filleting, second is after. The fillets look wonky, but perhaps they are the correct result due to the shapes? File included.
Flange.3dm (371.7 KB)
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It is the shape you would expect with a rolling ball fillet - the cross-section arc will be shortest at the shallowest angle of intersection and longest at the steepest.
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I’m not familiar with that. Is it an option in Sweep 2? Where do you find it? I can’t using RH8. Did you do the fillet in the sweep shape first?
Oops! Sorry. I see it shows in the pic you posted.
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No sweep. It’s in the fillet command…
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I see that now. But using that option still does not come out like yours. I’m assuming you worked with the file I posted?
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Yes I tried with your file.
My display mode doesn’t show the isocurves…
And there are three options, two quite similar.
Distance from edge and distance between rails
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I am using distance between rails. Even with isocurves off, still doesn’t look like what you got. My fillet looks a lot more wavy than yours.
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This is a perfect example where you could use the power of Loft and its “Loose” option. Here is a quick try, but keep in mind that the input curves which I built are not an exact match of the rounded rectangle curve used on your model. However, they let you build a very smooth lofted surface with G2 continuity at either end and with a very small amount of control points that are easy to edit.
The two cyan curves (#4 and #5) are extracted isocurves from the straight loft in the first image that was built between the white curves #3 and #6. Then I deleted the lofted surface.
The second image shows the final lofted surface with “Loose” option built from all numbered curves (#1-8). The white curves arranged in a row help to achieve G2 continuity. If you need just tangency, simply don’t use curves #1 and #8. If you want to achieve G10, add 8 extra offset curves outside the existing ones. You can literally achieve G1000 if you wish so. 
Curve #6 is a 1/4 of a circle which I split in 4 segments and leaved just one of them. Then I changed it degree to 7, in order to preserve the true arc shape while adding more control points needed for the lower curves. Then I made vertical copies of curve #6 that became curves #7 and #8.
The beauty of this method is that you can turn on the History recording on the lofted surface, in order to control its shape by editing the control points of the input curves. This way, it’s extremely convenient to make adjustments in a few seconds.
Flange.3dm (1.4 MB)
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I originally tried loft, but found Sweep2 gave a better result no matter which loft options I chose. Obviously my modeling skills are rudimentary, and even less now as I been away from the work for a year. I’ll delve into your instructions and see if I can replicate what you’ve done. Thanks for the detailed reply.
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Examples of the three types of fillets available in FilletEdge
FilletExamplesDC01.3dm (3.0 MB)
Note how the fillet width changes with angle between the surfaces. RollingBall and DistFromEdge change width in opposite directions as the angle changes.
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Another alternative for a fillet/blend is @theoutside “Pipe trim” method which results in a fillet/blend very close to the FilletEdge DistBetweenRails option but with a different, non-circular shape.
@CalypsoArt What is the “design intent”? A particular shape of fillet to suit a manufacturing method? Look “good”? ???
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This is a hobby piece – custom reference monitor stand bracket – to get me back into using Rhino after a long hiatus. I would like the piece to look as good as I can make it. Most important, it needs to be water tight to 3D print on my old printer. Of course my 3D printer is old and cheap, so looking good is all relative. Starting with a good model helps.
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Thanks again. I have not tried SubD on this. I have dabbled with it before, but have never got a handle on it even after doing many tutorials (Kyle’s guitar and others) and getting help here from you guys. There is a thread I started in 2021 on a SubD spiral detail I needed to make. Even after much help I never got it right. I ran out of time and we built/sculpted it from images and 2D drawings. I don’t think I’ve attempted SubD since. Still so much to learn.
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