Thank you for your answer.
Here is some additional information concerning the problem raised.
1 - Rule of the Spiral.
Freeform curve used as a guide to create a pipe with a square section.
Needed Tolerance for FAB
Purpose : Metal casting.
Transformation Needs : MSR
Since the loss of precision after casting varies between 1 and 3 % for the intended purpose, it is necessary to be able to apply precise compensations on the profile at the CAD stage.
2 -The construction of the spiral
Since the shape of the guide curves has to be arbitrarily adjusted for purpose-related reasons, using a parametric spiral model does not seem relevant.
However, if it is possible to set up a spiral parametrically that can conform to two guide curves, this would make the implementation easier.
GH is probably one right path for this…
If we stick to Rhino, one way of creating of such a spiral from manageable guide curves could be focus on easy to control guide curves:
- Create two clean guide curves
- Find the average curve
- Create a spiral around the averaged curve starting @ 50%
- Rotate/Copy the resulting spiral
- Use the 3 levels of control offered by the guides to adjust things if needed.
There are naturally many other ways to work around the creation of such a spiral with Rhino.
the method described by @encephalon is one such.
What must prevail is the ability to adjust the profile downstream.
This is why it seems relevant to me to focus on the behaviour of the profile on the rail as well as on the ability to modify the characteristics of that same profile in a second stage.
That the idea, yes.
While understanding this concept is within my grasp, I admit my inability to describe it in the form of a Python script.
Rhino not being parametric, I am facing a certain limit that can probably be crossed with GH.
As far as I’m concerned, not being skilled in coding, I don’t really have any other choice than GH or an existing plugin ( I really don’t like this way ).
But in the absolute, I have the feeling that a Python script would be a more transversal solution…