Weird Fillet Surfaces

Hello everybody,
I noticed the FilletEdge command produces these strange fillet surfaces in certain situations. Naked edges into the bargain as well. Don’t know exactly from which version Rhino started this weird behavior but I’m pretty sure it’s not long ago. I stumbled upon it today on the latest Rhino 7 release but it occurs on Rhino 6 as well. Running FilletSrf produces the usual results as you can see in the screenshot.
Fillet.3dm (430.0 KB)

hi Samuel, I deleted the outer fillets, then used blend srf. then filled the center one with a 2 rail sweep. had to do a little surface extend then trim.
Maybe not what your looking for.—MarkFillet.3dm (382.9 KB)
oh, I noticed that the fillet was not tangent either on your example in the middle.

pretty bad indeed.

If you do in one operation (so both the 2mm and 0.5mm at the same time), you will get this:

interestingly, if you do it in two steps, it works as well:

Hello - thanks, I see this. It looks like this is caused by the way the left end of the corner fillet hits the left most fillet - the ends do not line up cleanly in the order they are created internally, is my guess -


RH-63470 FilletEdge: messy result


Thank you Mark, actually I just wanted to point out that the FilletEdge command has been made worse with the latest updates. At least in this particular case.