Spiral Staircase Model #2

Here is my second spiral staircase model.
Here are the dimensions:
Height of riser-200mm
Height of floor-3000mm
Diameter-2600mm
Number of tread-14
Number of riser-15
Rotation-360 degrees
Angle of stair-25.71 degrees
Length of stair-1000mm
Width of stair in the middle-240mm