Hello to all,

I m quiet new on this software, and I m looking how to generate a smooth junction in a Y shape (see attachment).

Does Rhino or other software could do the job easier?

Any advice?

Thanks

Fred

Salut Fred, here's one method that could be explored and refined:

-Blue Half ellipse sweeped on the three paths,

-Planar was used for the blue shape, created with the top three edges of the sweeped surfaces .

-Caps created with ellipses and planar.

-Model has been scaled 1/10 to join it in one solid.

-Rotated 90 to work with flow/curve.

-Legs have been trimmed (red)

-The blue surface have been trimmed and blended.

I imagine the Y shape could also been simply extruded, filleted and squished with the scaling handle.


Marc

Hi Fred, branching structures are difficult to do in NURBS modeling in general - it can be easier to do branching structures in a sub-d polygon modeling program (like Silo, Modo, Cinema4D, etc...) rather than in a NURBS modeling program, the way that sub-d works by kind of melting all the resulting surfaces together works well for that kind of a thing.

Basically with stuff like that you're getting into more organic modeling territory and less into 2D profile curve driven modeling which is where NURBS modeling is strongest in.

There is a technique for using surface blending for making a Y-branch in MoI though, which you can see an example of here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=4388.55


But probably really the shape that you're showing there is better suited for polygon sub-d modeling techniques which are a better fit for more organic shapes, rather than NURBS modeling techniques, although maybe Marc's method above may work for you too.


Also another thing you can try is to build it flat initially and then use the Flow command that is new in v3 to deform it into the bent position rather than building the whole bendy thing directly in place, sometimes that can ease some kinds of constructions.

- Michael

Now that I read Marc's reply again I see he also used Flow - that definitely helps a lot since it is much easier to construct the juncture area to be all smooth on a flat piece, then produce the bending of the entire object all at once using Flow rather than trying to construct things initially in the bent position which will make it more difficult to build a smoothly connecting center area.

One quirk with curve-to-curve flow right now is that it tends to rotate things by 90 degrees unless you place both the base curve and the target curve in the world x/y plane. So for a case like this, rotate your shape so that the bent path curve is in the x/y plane rather than going vertical, then Flow works by having a base curve (which is usually a line going down the center of your object) and a target curve like this:



Then you select the object, and run Transform > Deform > Flow (which is a new command in v3), then select the line as the base curve, and the bent curve as the target curve and it will produce this result:




Anytime you can primarily create your design as a flat 2D object will tend to make things much easier and then fit better with the primary NURBS modeling method which is focused on drawing 2D profile curves to guide the construction. If you find yourself trying to patch together a bunch of 3D curves directly, that tends to be a sign that you're trying to use sub-d modeling techniques rather than 2D profile curve driven NURBS modeling techniques.

- Michael

Thanks all for your time exploring solution to my problem.

I appreciate!!!

Fred