Issue with Curviloft

[dpd]

Hello!
Curviloft is awesome! I am trying to use it for this task:
I want to loft this -

Into this -

So far, so good. But the precise shape is important. The result has this deformations (copied into 4 corners):

In all 4 corners where the quarter portion is connected, there is a curl inward. The transition is from a perfect circle to a rounded rectangle with all angles bulging outward, there is no inward crease in the base shape:

It still happens, whether I do it in quarters, or halves, or the whole shape at once. See the creases going inward where the quadrants meet. I have tried every combination of settings in the curviloft options. What am I doing wrong? Anyone know how to get a basic loft that follows the geometry, without adding the inflection inward?

Thanks!

[Rich O Brien]

Easier investigate if you share the SKP file.

[Mike Amos]

I thi nk extrusion tools might be better for this instance. I end up trying both as they can return distinctly different results but usually one OR the other will do the job.

I have seen this issue many times.

ALso, do all the arcs have the same number of segments or multiples thereof?

[dpd]

Thanks for the replies.
I made sure that the arcs have the same number of segments (40).

Curviloft problem.skp

I tried Extrusion Tools, it had the opposite problem. The seam bulged outward instead of curling inward.

[Mike Amos]

Try changing the order of extruding profiles/arcs, you can get quite different results. Also, either the same number of facets or multiples thereof rather than different numbers all over the place. Much cleaner results whichever tool you are using.

[dpd]

@Mike-Amos thanks Mike!

What do you mean by changing the order? Do you mean selecting them in a different order before execution?

I have been using the skin function with the whole shape selected before pressing the button.

[Mike Amos]

Correct, if part of the arc is a more or less straight line, it will 'inform' on the final result. You can break the arc too with the more or less straight part seperate and it WILL still extrude as long as it was part of an arc (Glued) previously.

[Mike Amos]

@dpd

First I just extruded the base vertically. Second attempt I added a step.

Copied the top arc and placed it as seen in the second image, scaled to fit and extruded. I think this is the money shot.