# What is a good strategy for rounding corners on complex geometry?

I wanted to please discuss what is the best strategy for rounding edges on a complex surface. The surface is curved and has many differently spaced perpendicular faces/edges. If I understand correctly, my best option is to use RoundCorner but to manually select some of the edges? The offsets are overlapped if I try to just select the whole face.

I can pick one small part of an edge, but then I’m stuck with trying to clean up the faces it creates on either side of the rounded edge.

I would be happy if I can just round some of the larger edges, but I just don’t know how to push pull the surfaces, it seems to not work.

Are there other ways of doing this or an guide to rounding corners on complex geometry?

As always, thanks for any ideas.

I can give you a quick way so that it looks like rounded edges - depending on scales, this might work for 3D printed stuff too:

• put an internal contour around the shape (offset)
• double click to select the internal shape and raise it up a bit.
• shift-click the middle shape to de-select it and then “smooth” the remaining selected edges.

If you do this in a couple of gradated steps it would simulate a true curve.

For your ring, I would be tempted to start with a flat swordfish, bevel it in the normal way (follow me with a curve), then bend the whole result to the curvature of the ring.

Your swordfish contains some sharp corners (e.g. the ends of the fins), a narrow slot at the mouth, and a bunch of short segments along the back of the top fin. In the screenshot, it appears that the roundover you are trying to use is large compared to these features, and that will cause problems because the geometry of the rounded segments can’t intersect cleanly at the corners. I’m skeptical (but open to enlightenment from experts) that you can round this profile with such a large radius roundover without having to do a lot of manual repair afterwards.

Thank you for the ideas. I did think of using the “offset tool” and individually work with edges that way. But the surface is curved so I can’t use the offset tool.

Yes, even if I turn the offset down to .05, there are still overlaps.

Are the orange boxes what I can perhaps grab and manually fix the overlapping offsets after running the roundcorner like in my photo?

This is how I would do it (from flat - assuming you bend it after beveling it)

• double click to select the swordfish and it’s bounding geometry.
• copy
• paste outside somewhere and group it.
• copy and paste this group (you should now have 3 - original, working and copy)
• edit the working group and off-set the shape internally
• I’m only interested in the inside shape; double click on the inside shape and see if there are any areas of it that fall outside
• draw lines to chop off the extra bits (make the line follow the blade of a knife and don’t worry about it starting/ending outside of the shape)
• double click on the inside shape again to select it and all bounding edges.
• make into a group
• use the outside geometry as a reference to move this new inner shape on top of the copy group.
• cut it
• come out of the working group and delete it
• enter the copy group and “paste in place”
• explode the group and select the inner shape again
• move it up by x

Still needs a little bit of tidying, but it’s 95% there.

Actually - slight brainwave; why are you wanting an internal bevel? shouldn’t it be an external bevel? that is sooooo much easier; just select the connecting edges and then the ‘follow me’ tool for the desired router shape.fishie.skp (319.3 KB)

Thanks for the specific idea. I will try this tonight. I’m sure the
problem is that I still have a lot to learn.