How to Create a Surface From Multiple Cross Sections

Hello, I have a question regarding surface creation from a set of curves. Below is a picture of the curves that I am using to create my surface.


What I would like to do would be to create a surface using the bottom circle and top “slot” curve, as my rails. The two verticle curves are the cross sections that I want the surface to go through.

Here is an example of the type of surface I’m looking for using the Sweep2 cmd.


This surface was created using the top and bottom curves as my rails, and the verticle on the right as my sweep shape.

It’s fairly close to what I’m looking for, but it does not align with the vertical curve on the left which is clearly seen in the photo below:

What is the best way to generate to generate this type of surface?

I’ve tried splitting the shape into quarters and using commands such as, NetworkSrf, and Sweep2 (with both vertical curves as my sweep shapes), and then mirroring it until I had a full circle. And while these options were close to what I was after. neither of these options produced good sections in my opinion.

Please let me know if there is a better way of achieving what I’m after.

File:
Curves Test.3dm (2.3 MB)

Thanks,
Asher

quick and dirty

build additional helper surfaces (green) (extrudeCrv, splitatTangent = no ( _useExtrusions Polysurface) not sure if it works with objecttype extrusion

select the edges as rails (important)=
use 4 symmetrical shapes/cross curves
do the entire surface in one shot. “closed sweep” option,
refit rail
tangent option (only available if you took the surface edges as rails)

this will be suitable within document tolerance.

Curves_Test_tp_00_rh7.3dm (3.0 MB)

the input curve with the straight section and the 1/2 circle have tangent continuity.
this is not handled nicely if you check with _zebra for example.
the surface is quite “heavy” - regarding amount of cv’s

more advanced

only build 1/4
surfacing is often a compromise with tolerance, especially if you use arcs / circles:
they are represented with Nurbs Degree 2, a special Knot structure and weight.
especially weight and knot might cause problems with some surfacing techniques or with some commands like MatchSrf.
If you can accept an approximation (+/- 0.02 mm of an real circle) use a surface with 4x6 Cvs and Degree 3,5
for example use
_edgeSrf and _rebuild with above settings.
_matchSrf with tangent

hope this helps - kind regards -tom

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