I made up a challenge of how to construct an elliptical, spiral staircase on the attached surface (it could be wider, it’s really just a hypothetical exercise, not a real-life example.
I was experimenting with shape blender, which is a very impressive plugin, but I couldn’t define the right spine to make it work. So that would be interesting to know how to define a spiraling spine if you have a geometric or elliptical shape like the one attached.
Any constructive suggestions are welcome!
Just a test with Flowify and Curviloft
To maintain an even pitch might be a bit difficult. The landing helps a bit, perhaps.
Yes, the landing helps to maintain the pitch of the steps. The width of the steps and the two perimeters of the wall (top, bottom) also matter.
waooo… I am still working on it :)))
I was trying to divide the curve - originally 94 segments into 25 (level of steps…)
bur CURVILOF picks up all junctions (division and segment) which will not give me the desired 25 vertical divisions.
I created the horizontal division by slicing the shape with planes, but I realize now that this also could be achieved with curviloft…
I should have used 25 segments to make the original ellipsoid curves…but is there a way to correct this? I tried altering the number of segments in ENTITY window, but it isn’t accept any changes
Is there a mathematical way to define a curve like the one I scribble on mihai.s’s model?
like an even rise between the start and end point, following the surface? 
I achieved this through a rather unclever - manual - way…by connecting the division point on the curve…rather than finding a way to modify an existing curve into a curve with the right amount of segments …
This should give me the right rise…
Yes, it definitely solves the problem in the case of a simple staircase…I think I was going this way too, but as I was focusing on using Shape Bender in order to be able to automate the process…and be able to use more complex straight stair designs…but it is possibly a step too far…
I was wondering how could I determine the right spine to make a “ramp” between these two landings…I am thinking that if I could do this then it would be one step closer to the solution above. But in reality, I don’t really have it figured it out, so it might just be a dead-end street…never the less, this problem is buging
me now…
elliptical cone shape…
Manually, I can do it, but not sure if I could find a smoother solution when I have smoother segments…It is always easier to work with segments, because it simplifies the curve and makes it workable, but alternatively, I feel that the final result should be smooth…
for example, if you want to send the sections for laser cutting or printing…
Then… do it… with more segments or… use SUbD for that
That’s a good idea… I will try to replicate this to practice…thank you 
