I am sorry, but that is not the problem, the curves do not follow a smooth path, there is a dent in the skin, either at the bottom, or left and right, depending on the vertical curve.

Maybe you could draw those top curves in to use as construction geometry instead of looking for sweep to adhere to the unknown

I would use blend to create the top curves from the surface to the point, then have 4 tangent curves to work from

Cant test without a file…

You want or don't want this dent ? :)

ok, I will rephrase my question: how can I finish this lofted open shape, so that the end is smooth and round and has no visible division line, so that it looks like one continuous smooth object?

thanks
wim

Maybe Network ?

HI wim,

re:
> how can I finish this lofted open shape, so that the end is smooth and round and has no
> visible division line, so that it looks like one continuous smooth object?

It's hard to give good advice just looking at a screenshot, can you please post the .3dm model file with the objects you show there?

Probably the first thing I would try would be to use Rail Revolve to make the rounded end and then have some empty space between that rounded tip and the main part and then use Construct > Blend to put in a smooth blend surface.

Or another possibility is to cut the end edge in half and then use Blend between the 2 halves.

Also using Loft with Loft style = "Loose" and ending in a point can be good, an example:
https://moi3d.com/forum/index.php?webtag=MOI&msg=6082.8

- Michael