best practice for curving a surface

[michaelarturR6AYB]

Hi,

I have a planar surface in a violin plate shape. Now I would like to curve it to give it the shape of a real violin plate. What would be the steps to achieve this the easiest way? (The surface was created by converting the outer polylines into a surface)

this is the surface? 

[VincentSheehan]

I drew a quick shape in half. I used Loft then selected the following lines that profile the object.

1. Red Polyline.
2. Yellow Polyline.
3. Right click then choose Guides at the command line.
4. Select the Green Arch Polylines.

[leeminardi]

First off, don't work with polylines!  Learn  how to create and edit spline both with Ft points and CVs. Since the violin is symmetrical work with one half of the model with plans to mirror it later. Be sure to ensure that the spline's tangency at it ends are horizontal along the seam between the two halves.

You might start with a couple of splines as I have below (red and green).  The box is used to help define UCSs and visualize the 3D aspects of the geometry. 

Now use loft the create a ruled surface between the two splines.  Usually I would use the Path or Guides option at this point but the violin profile does not lend itself to this option.

At this point you should have a NURBS surface. Change the CV Hull property from Hidden to Show.

With either the X or Y axis of the UCS vertical (Y in my example) turn on orthomode.  You can nw select individual CVs and move them vertically as desired to yield a convex (or concave) surface. The image shows the result of transforming the ruled surface to a more scupltured shape.

Use Boolean subtract to create the holes after you have the surface you want.

[michaelarturR6AYB]

Hi thank you for your guidance! I tried to follow your steps and got to the point where I could create a curved surface with using loft on two splinesGenerated Nurbs Surfacelofted Surface (not a NURBS yet).

The problem I have is that the nurbs surface that I get has a very high number of control points (much more than you have in your example).

Is there a way to pevent this? (I think it makes curving the surface very hard with so many points to set manually?)  The first picture is the NURBS and the second is the lofted surface that is not a NURBS yet

[leeminardi]

---

@michaelarturR6AYB wrote:

...

The problem I have is that the nurbs surface that I get has a very high number of control points (much more than you have in your example).

Is there a way to pevent this? (I think it makes curving the surface very hard with so many points to set manually?)  ...

---

It is important to try to use as few Fit Point or CVs as possible when creating a spline.  Mor points does not necessarily yield better quality.

Can you post your drawing?

[michaelarturR6AYB]

Hello,

thank you for you help! I upload my drawing maybe you can see what I do wrong. I also tested to replicate a drawing like you did woth only 5 CVs but I also yields to  a very big number of points on the created NURB.

[leeminardi · Accepted solution]

Here's an approach that shows some promise.  I've outline the step in the attached file.

UCS with X axis perpendicular to the plane of the surface.

When adding CVs to the NURBS you will need some near the edges so that you can move up CVs that are more towards the interior without changing the violin profile. Check out the options in the Surface ribbon menu where you will find SHOW CV and Add CV. Using the CVADD feature takes some practice. Make backup copies as you work. When using Add CV I found it best to work in the top view. Endter "D" once to switch from the U to the V direction.

Let me know if you have any questions.

Lee

[michaelarturR6AYB]

Hi thank you so much for your help and showing me all the steps in such depth this made things much clearer! I have another question about the concept of CV's. When I add CV's to the NURB I always create squares with the neighbouring lines of CV's. This way it seems like it is not possible to let the curvature rise from a smooth curved line (like the outer body plate form line) but only a cornered line. I saw there is an option to place single individual CV's on any position on the NURB (which would solve this problem I believe) but when I try this nothing happens. 

[michaelarturR6AYB · Accepted solution]

I think now I sorted it! Thanks a lot again!