Outrageous stair stringers to spiral stair

[Darius M]

I'm trying to create a continuous stringer with consistent offsets from the top tread and underside, similar to the stringer on the right side of the stair (although that one also has a connection issue).

The start and end points of the stair must remain unchanged.

This is a single-flight stair with a transition point where the large-radius section meets the winder section with a smaller radius.

So far, both approaches have failed - whether using the default stair stringer settings or the railing tool.

At first the exercise seemed straightforward, but I’ve run out of options after trying walls, morphs, curtain walls, and even meshes.

I’m also concerned about how problematic this will become once I start adding the inner posts.

I’ve included the model file in case anyone is willing to take a look and help.

https://drive.google.com/file/d/19sofG2u-7KrevFIwsZHI9wOxUeutqoDH/view?usp=sharing

Operating system used: Windows 11 23h2

[Christophe Fortineau]

Hello @Darius M ,

I am used to model these with railing tool and complex profil.
Did you try by this way ?

[Darius M]

I did, but the internal spindles couldn't be generated to an acceptable solution. I ended up doing the stringers, underside and balustrade in 3ds Max and kept only the treads and risers.

It was very counterproductive to model half a stair in Archicad the whole day.
I did get some exceptional laughs along the way with just one click errors.
I truly hope Graphisoft will eventually make the stair tool work 

Just for information, this was the expected result - which I converted in .fbx and then to morph.

 

[Patrick M]

yeah... about that... the stair and railing tools are an amazing tool, when you have weeks to trouble shoot and customize or are just targeting "good enough". They are built with specific limitations that are often exceeded, especially when curves or tight corners are concerned.

For this specific stair, I'd probably avoid the stair tool to begin with, if for no other reason than the balanced treads. I've found it virtually impossible to model a code compliant tread layout for winder stairs. And if they are code compliant, they are the result of the stair tool solving a path, not placing treads/risers/nosing where I need or want them.

I know you said you've already gone down the path of using other tools; but I would probably model the treads as slabs, outline with a morph, trim that morph to a mesh for the underside and top of stringers, and trim to the slab/treads.

Most people I train just jump strait to rhino for stairs like this.

I'm sure someone at graphisoft could spend a few weeks putting together a series of favorites and get this to do exactly what you want, but no one in the practice has time for that. I'm just very thankful the stair tool works as good as it does... the old stair maker feature in archicad was super clunky and impossible, even for the most basic stairs (although it could do spiral stairs better than the current stair tool).

[Patrick M]

not that it helps in your case, but here is a method I used to model as spiral stair... the key is that you can't expect to get it all with one element (https://youtu.be/fhlyHch1ccg😞