Spiral stairs


I am trying to make a spiral stair case in rhino that has a 27 feet diameter but the actual width of the stairs is only 3 feet. When I try to do it, the center of the axis is where the stairs begin so the width of the stairs end up being the 27 feet. Is there a way to do make the stairs smaller, without using the center of axis? ( you should be able to see right through the center of the spiral staircase)

(should look something like this)


You can do this with the ArrayPolar command. That will let you set a Z-Offset, as well as an ‘Angle to Fill’ value. this is cumulative… e.g. 2 full rotations would require a value of 720° (2 • 360).

But it might be easier to just work out One Full Turn (360°), and then copy/paste (or/ linear array) additional levels along the Z-Axis.

Remember to keep the object ‘Rotate’ option turned ON.

Here’s a test example: albeit without any of the interlocking aspects of the treads, or handrail.

JimD have good one but i use another techniek, this gives me more control over.