Problem with Multi-Section Surface

[philyherb1]

I have a transition surface that fits between a circular shaft surface at the bottom and a
constant section surface at the top.
There are 16 planer section curves and 2 guide curves (one on each side).
Analysis of each section curve and the guide curves show a (generally) gradual curvature
to the curves.
Using “Generative Shape Design” and “Multi Sections Surface”, the result is a surface that
sinks between each section curve.


How can I prevent this?

 

[MrCATIA]

Hard to suggest solution for smoothing out the dips without seeing the model. And where did all the transistion data come from?

I have a couple things for you to consider:

1. If tangency was imposed at each section, remove it. Same with tensions.
2. I'm guessing you did not specify a spine - good.
3. 16 sections seems like too many. Try again by using every other section, or every third section, and let the guide curves do their job. Then compare the result to the sections that were ignored.
4. 2 guides doesn't seem to be enough - can you add one or two in the middle?
5 try different coupling options. Tangency or Tangency Then Curvature seem to apply to your data.
6. try reversing the direction, with 2 guides used as sections and some of the section curves used as guides.
7. instead of one big multi-section surface, try breaking it down into 2 or 3 surfaces.

And remember: Different CAD tools use different surfacing algorithms. It is almost impossible to match surfaces 100%.

If you already have worked it out, please share your methods with us.