Hi niko, I'll see what I can come up with.

My first impression is that you seem to have several bumps or undulations in your main fuselage like here:



Also notice how the seam edge on the fuselage is not very orderly, it wavers around quite a bit?

Lumpy and bumpy things similar to that do not bode well for filleting - part of filleting involves creating a surface offset and little lumps and bumps and irregularities do not go along very well with offsetting.

- Michael

Hi niko, my first quick attempt with fillet was successful, I've attached the 3DM file which looks like this:




So note that you have 2 open surfaces here so that means that you'll generally want to use the Trim command to slice them with each other instead of booleans.

To do the cutting, select both the fuselage and the wing, and then run Edit > Trim.

At the prompt to select cutting objects, just right-click or press Done because you want them to cut each other.

Then at the prompt to select pieces to discard, switch to "Keep" mode instead, because it's a bit easier to see the pieces you want to keep in this case. Select the part of the wing and fuselage that you want to keep and then right-click and the interior parts will be trimmed away.

Use Edit > Join to join those pieces together into one connected piece.

Then I selected those joined edges at the juncture and ran Fillet, with a radius of 15 units, which produced the attached result.

The fillet will be a bit wiggly because it is adapting to the bumps and wiggly nature of your fuselage - you probably want to have a cleaner and less bumpy fuselage to get a better quality overall result.

Hope this helps!

- Michael

Hi niko, also one thing to note with Fillet is that it won't cross over other nearby separate edges, so for example this edge here:



places a limit on the fillet size, the fillet needs to be small enough so that it will not run into that edge there.

- Michael

Beat me to it... I capped off the 2 surfaces to make solids, then did the boolean and fillet.

Guys thanks.

Michael in a previous thread you told me that it was easier for the command to fillet two surfaces instead of edges of joined surfaces. Why is that method not working here?

Hi niko,

> Why is that method not working here?

It's because your wing part is not just a single surface, it is made up of 4 surfaces joined together.

Note that when you select it, the object type indicator (circled in red below) says that it is a "Joined srf", and not just a "Surface" like it would if it was just 1 surface.



And similarly the fuselage is also made up of 2 surfaces joined together.

You could still use surface/surface filleting by breaking things down into individual surfaces by selecting them and running Edit > Separate.

But that surface/surface filleting will usually be something that you would try if the edge-based one is unable to figure things out.

It can be harder to deal with the surface/surface one when there are multiple pieces involved because you may need to do things like trim the fillet pieces manually and stuff like that.

- Michael

Got it thanks.