You can't do this correctly (in SolidWorks) in a single feature. What Ravi showed is fine if you're just looking for an approximation, but the attached image shows 3 places where it is wrong. You can't get the curl around the outside correct using a single Boundary feature. I notice the concave spot is caused by the original curves provided.
The curvature that comes to a point does so on both ends. This is maybe an ok first approximation, but you can't really use this technique to get it right. The curl goes around the whole body, but the feature is set up from a grid, and the grid changes relation to the curl. That kind of thing never works. So You put it in, and then you take it out, and recreate the curl in some other way that goes around the whole body - use a method that flows the way the geometry flows.
In the center, you're ok with the XY grid until you get to the curl, then you need a second feature to flow around. The center area was made with a 3 sided degenerate boundary, the way you set it up. But I cut off the degeneracy (where it all comes to a point), and made a second boundary of two closed loops. There's a ruled surface in there used as an angle reference to get the curl without doing a lot of sketching.
I can see too that you are trying very hard to constrain splines. Maybe too hard. I used all 3 pt splines with handles. I try to avoid internal spline handles. I've had them freak out on me too many times, changing the shape of the spline without warning.
Anyway, I would be more careful about the shape of the trimming spline (sketch2) if this were anything but an example.
Best of luck.
Guitar.surface1.SLDPRT.zip 5.0 MB
Thank you Matt and Ravi, for taking the time to work with this.
Yes, I began to realize that trying to constrain the surface in all the directions you mention, was something which was not going to work. I also needed to work on my curves better, and I am doing that now.
Like you mention, I will need to deal with each segment seperately, and then stitch the whole thing together. In areas where I need a better blend, I will probably delete small areas and then patch to achieve a better result.
I never reall though that something like this will take the amount of work it does, not that it would be so complex. Modeling a car seems easier than this! LOL!
It even gets more interesting, since the bottom of the surface, will now also need to vary in thickness from the re-curve, to the center. Which means it needs to be constructed seperately again, and then lofted...and that is only for the top of the guitar, as it would require an equal amount of effort for the back! WOW! LOL!
Anyone have a laser scanner I can borrow for a week? :-)