Fillet edges with Sharp corners


I’m having problem with filleting a solid…
On the left side, rounded shape figure can be filleted(is this a word?) using filletedge.
On the right side, the shape has obvious too tight corners that fillet is not possible.

Is there a good approach to fillet edges in solid that has sharp corners going in and out from a solid? I at least want to get the edges going out to be rounded.

I’ve been searching in the web, but it all leads to “t-spline”, but haven’t found that in Rhino mac…

If the edge curve is smooth (no kinks), and the radius is small enough to fit without doubling back over itself, the FilletEdge should work just fine.
You can also add additional fillet handles in the tight curvature areas with a smaller radius that will work in the tight corners to make a variable radius fillet.

Just a thought… if the fillets do end up doubling back and overlapping, would it not be possible to have the overlapped surfaces trimmed off?

I’ve actually ended up doing a lot of this type of thing manually… filleting (or manually creating via sweeping) adjacent edges that meet at an acute corner, then manually trimming off the overlapping parts and joining the remaining surfaces together.

It would save me a LOT of time if the fillet and chamfer tools handled sharp corner overlaps a little more intelligently.

Yes that would be nice…
I also always use the filletedge rather
than with normal fillet.(surface)
I can’t get the surface fillet to work many times… is there advantage over the other?

But then it would no longer be a fillet.
You would be better off to delete the fillet surface, manually edit the kinky corners, then use a Blend if all you’re after is smoothness and not an accurate circular fillet.

Maybe the issue is that the fillet tool was designed to create a specific kind of curved surface on inside corners, and many of us are using it as a “roundover” tool on outside corners.

I would expect a roundover tool to work like running a router bit along an edge. You get a crisp intersection of curved surfaces where you have radiused edges meeting at a corner.

So maybe the fillet tool needs to behave differently on outside corners, or there needs to be a proper “roundover” tool that behaves more like using a router to apply a curve to outside edges.

Your Router simile is a good one.
Rhino can’t do that automatically because the surfaces do not exist until after the command is completed. We can’t find the edge of a self-intersecting surface, and we can’t calculate the edges of two intersecting surfaces until they exist. We need two existing intersecting surfaces to find where they intersect and trim them back.

Thanks, John.

This discussion has been useful in that it has helped to clarify in my own mind why the FilletEdge command works beautifully in some situations, but not in others.

Perhaps it has also helped illustrate and clarify that maybe we need a better tool than “FilletEdge” for rounding over outside edges. Maybe it could be logged as a feature request?

In Windows Rhino there is a feature called edge softening, the command is ApplyEdgeSoftening and it only effects the render mesh not the NURBS geometry. This can be a great way to quickly soften any kinks with a small rounding radius. I’m not 100% sure when and if this command can be added to the Mac version but I know it’s on the list for sure. If you can do your work with a mesh as the end result, this would be an alternative to FilletEdge but not a numerically precise one in comparison.

Nice router cut!
I need to learn how to do that.
Well I need to learn many things…

Thank you to John, decibelguitars and Brian.
I’ll keep on studying


If it’s not too much trouble, could you let me know how
you got the nice curved surface in the corner?


Not at all!

What I do is fillet the edge on each side of the sharp corner separately, extending the filleted surfaces so they intersect, and then use Trim or Split to remove the extra surfaces.

Sometimes I manually create curved edges by running DupEdge, then offsetting it on each of the adjoining surfaces, and using Sweep2Rails to make the “roundover” surfaces, then trim and join everything back together.


Thank you for the advice!
Got it working with the surface extend then trimming.
I need to work on tge dupedge command, but I think i got what you mean.
Thanks again!