Fillet problem

Fillet.3dm (149.8 KB) Can anyone tell me how to create a fillet between the 2 surfaces in this model? I want it to run around the outside of the grey surface and red surface but the fillet command always sees the grey surface as 2 seperate surfaces (or more) however I create them.

I’ve tried creating the surfaces in different ways - lofts, sweeps etc to get continuous surfaces but the fillet never works correctly.

I’m on Rhino4 btw.

Join the surfaces together first and use FilletEdge. Here is is with a radius of 1.

You would also do well to run ShrinkTrimmedSrf on all three surfaces, and MergeEdge on the red trimmed surface. That will simplify a lot of the hidden geometry you’re carrying.

Many thanks John!
That tip will come in handy in lots of instances!