Making a outer catwalk stair, need help

[Darkspear]

was trying to make tower with large block 3x3 Large blocks, with round corners. got 4 interior walls as center on each side and a round corner on each side.
Initial start goes like this.
Grated stair placed in front of the right most round corner
Grated catwalk corner to make a 90 degree turn left
Grated stair, grated catwalk wall (railing one side) followed by a grated stair again
Grated catwalk corner to make a 90 Degree turn left.
Rinse repeat

My problem is i cant place it without support, and when i remove the scaffold support most of it fall down again.

I can place the first stair, then corner and another stair (with support), then the single railing catwalk.
when i remove support, the corner and following stair fall down, and i am left with the starter stair and catwalk up high.

What am i doing wrong?

Before cutting support scaffold
https://steamcommunity.com/sharedfiles/filedetails/?id=2004293038


After cutting scaffold
https://steamcommunity.com/sharedfiles/filedetails/?id=2004293155



Trying to make my own version of this (only using it for myself in sp survival)

All credit goes to Author https://steamcommunity.com/sharedfiles/filedetails/?id=1941665441

[aRPeaR]

Instead of using scaffolding, use a corner light to connect the grated stair placed in front of the right most round corner to the grated catwalk corner.

[Darkspear]

So many "thank you"'s..... works like a charm