Draw a  concentric circle of radius 70 mm and 10 mm respectively
Draw a horizontal line from center of the circle to radius of big circle
Trim the inner portion using trim command
Using Polar Array Split the circle into Eight Parts
Explode the lines created by polar array using explode command
Divide The horizontal  line into  12 parts as shown
Draw Arc (Start center end ) as shown
leave gap for the 7th division
and Start with 8th one from first
Join all the intersection points using spline command as shown
Here is the required spiral
