Here is an example of how this would be done on the ground and as you can see there are no circular lines to align the spiral arms in the photo. This is a partial build to show how the circles would have to be aligned and how it all expands!
The expansion obviously is relative to the sizing of each circle in the sequence but at the end it all aligns to a larger ring at the periphery.
The distance from the small end circle to the centre of each arm therefore should be the same as the other three.
Please note this is a basic drawing example of the geometric principle at work. But it gives those who wish a starting point so that you know what method to use to construct a design model.