Surface extend problems maybe causing Boundary Fill failure

[peterg7X5LU]

Hello,

When I try to extend the below surfaces using the Natural option, they fail, leading me to select the Tangent option instead:

But the problem with selecting Tangent is that it then seems to cause lines on the extended surfaces, which I think later leads to a boundary fill failure:

I've attached the file, and would appreciate it if somebody would take a look and show me how to fix please..  The 8 extensions I performed are immediately before the Boundary Fill in the timeline.

[TrippyLighting]

I am not entie3ly sure what you are designing, but I would not approach such an object the way you do.

For example, there would be no 3D sketches whatsoever.

I would also make sure the curvature of the curves that I use to create surfaces with are smooth. The latter clearly isn't the case in your design:

I would also build this from surfaces that are overbuilt from the beginning, so there's no need to extend surfaces.

[peterg7X5LU]

I do not know how those unsmooth red curves occurred.  To draw the vertical curves along the z-axis I just drew a fit-point spline.

I will try and overbuild the surfaces like you suggest.

[TrippyLighting]

Have you considered using T-Splines for this?

[peterg7X5LU · Accepted solution]

I tried using Control Point Splines for my curves and the surface creation and boundary fill works much better...

Thanks for the pointer.  Design progress has increased greatly considering I have a day job that is not design-related!