Draw lines from points A & B to the point where the bisecting line intersects the circumference (at point C) creating half lines.
2. Draw line from the radius origin to the circumference (at point D) passing through the mid point of the half line.
Stair wall lines Two established points Radius origin
3. Draw quarter lines by drawing lines from points B and C to point D.
4. Continue dividing lines in half until all tread widths are found.
