How to add a torus to another shape

Question

So I've tried everything I can think of (which isn't much, still pretty new to this), get figure out a way to get a loop shape on the top of this figure.

This is for the top of an earring that is going to be 3D printed, so I'm having trouble with a few different things (non-manifold and keeping it big enough are 2 of them).

I cut a torus in half, shaped it and merged it with a bunch of the axes at the top of the figure. When I subsurf it, the shape gets a little wonky. And when I try to remove non-manifold geometry, it just completely removes the torus from my other shape.

Is there another way to do this type of thing (add loops onto tops of earrings and such). Particularly if you are going to be subsurfing and making a lot of curved figures. Any insight appreciated, thanks!

Answer 1

Select Non-Manifold Ctrl-Shift-Alt-M and delete vertices X.

• Add two loop cuts Ctrl-R to ear-ring
• Add an additional edge F (selected in the image)
• Subdivide the new added edge W subdivide

This should look like:

Remove some loop cuts from half torus Alt-RMB , X loop-cut until the number of edges matches the other part.

Select two open ends and search for Bridge/Loft Space

Answer 2

You can try the little used Boolean modifier on your main object.

After setting the type to union and selecting your torus as the target object, (no need to cut it in half, just get it the shape you want and position it so it looks right from the outside.) you should see some examples of Z-fighting on the visible portions of the torus. This just means its working right! Apply the mod and delete the torus.

Sometimes this in itself creates some non-manifolds and even a few n-gons, but it should be pretty basic to fix.

Answer 3

The .blend file you uploaded does look really weird where the loop joins the main body. A common technique to counteract this is to add extra "loops" in the mesh to constrain the subsurf modifier.

This cgcookie tutorial illustrates the use of the loop cut tool to control the subsurf, although you might instead choose to subdivide pairs of edges to cut a face in half.

I have come across other videos that explain various anomalies that you can cause by using subsurf with certain topologies (poles, ngons) but I have lost track of the URLs.

Answer 4

Generally, your work looks fine. There are just two non-manifolds in your mesh: one overlapped face (Type: Multiple Faces) and one normal-flipped face (Type: Non Contiguous). You can press CtrlShiftAltM to check non-manifolds by types (be sure you are using Vertex/Edge Select mode).

How to fix: Delete the overlapped face, fill the hole, and flip the normal of another face, all would be fixed in a flash.