Creating a curved surface through Curves

 From:  Michael Gibson
4374.4 In reply to 4374.1 
Hi Jay, it can often be difficult to figure out a plan of attack when kind of blobby objects are involved.

One thing to look for can be any areas that go through a kind of a tight bend - those usually suggest that you may want to model them as sharp edges initially, and then use a fillet to round them off.

So for example the end part could fit like that:

If you don't have many areas like that you can try to build the tight areas in more directly but especially if there are several areas like that it can be easier to build them sharp to start with since that lets you pieces in separate chunks and you can then focus on a kind of smaller region of the shape at a time.

But the other end of your shape does not have anything like that, there's no tight curves, it's all quite broadly curved throughout:

So that means that you probably aren't going to put a fillet in the middle of that area there - it's going to be better to build that portion as all one big surface since it has all the same kind of shape throughout there. In your attached 3DM file you've got the intersection of 2 planar extrusions, and that will leave a big sharp edge in that area, so that's not going to be a good method for that area.

Network like Mike shows above can work, or also if you have a shape that kind of resembles a turned lathe type thing, you can use Revolve or Rail Revolve for those kinds of shapes.

With Rail revolve, you can give the revolve a trajectory curve which can be used to kind of stretch the profile as it swings around the revolve axis like this - here I've got 2 curves, the one on the bottom will be the path and the vertical hoop will be the rail curve:

Select the profile curve and run the Construct > Revolve > Rail revolve command, then the command prompt in the upper-right area of the main window will say "Select rail curve" - select the rail curve for that step. Then the next part is to select the ends of the revolve axis line, you want to put them at the ends of the profile shape like this:

That builds a turned result like so:

The 3DM model file is also attached.

- Michael