Connecting cylindrical hallways cleanly

Question

I'm a newbie modeler and having trouble connecting two cylindrical hallways. Appreciate any help given!

So here's the problem, I have a torus and a cylinder both acting as hallways in an environment I'm building. I want the Torus to connect cleanly to the side of the cylinder without intersecting it, then to remove faces between the two on the cylinder so someone can pass between the two.

I managed to get the Torus to connect cleanly by putting a difference boolean modifier on it as shown below, but I'm not not sure how to cleanly cut the shape required to have them pass through to eachother.

I've tried using boolean modifiers in a variety of different ways to see if I could somehow achieve it that but had no success. At this point I'm really just looking for someone to point me in the right direction so I can research a way to do this. I know I could just do it with the knife cut but I'd like it to fit perfectly.

Thanks in advance for any help!

Answer 1

One way to do this is to use Knife Project

In Edit Mode Alt click the edge loop of the smaller tube connecting to the bigger one. Then Shift + d (and Ctrl click) to duplicate it in position. P to separate by selection.

Now in Object mode select the newly made edge loop object, then Shift shift select the bigger tube (in that order).

Go into Edit Mode, line up the user camera view with the appropriate numpad key (because knife project cuts along the direction of this view) and use Knife Project.

Delete the faces and delete the newly made edge loop object.

Optional: in Object Mode select both tubes, press Ctrl + J. In Edit Mode Alt click the edge loop of both tubes and do Bridge Edge Loops.

End result:

You might want to connect your tubes differently (keep them separate objects for instance) but all the tricks needed are there. Hope that helps : )

Answer 2

The point is to have the good amount of vertices so that the two can fit easily.

If the cylinder part exposes from top to bottom 9 vertices (ring of 16) then the torus should have 16 minor segments.

Once done,

Boolean approach

Place the two shapes like so, so that they overlap:

Add a boolean union modifier to the torus using the cylinder as object:

Apply it. Cuts should be good but you'll have unwanted vertices:

So delete them.

The result should look good but warning check for doubles and/or overlapping faces (there will be some) and remove them. All should be quad after that.

Knife project approach

Place the cylinder along the torus:

Use a circle of 16 vertices too at the place of the last torus ring:

Keep the circle selected and the cylinder active, in ortho view (like the picture above) and enter edit mode.

Choose the menu "mesh/knife project". That will make this cut on the cylinder:

Remove these edges and faces:

Join the cylinder and the torus, enter edit mode, select these parts as below and use the menu "edge/bridge edge loops".

So that the two parts are now connected.

Common part

Now some clean up:

Make the opposite part quad using a knife cut:

Add some bevel using loop cuts CtrlR on these 3 parts: