This is a file I will use when testing whether I've resolved problems with my printer drawing circles.
I had to scale the design to 130% to have a single perimeter print for all circles. Please scale it to suit the nozzle that you're using so that only a single perimeter is made for each circle.
I hope this will allow me to clearly see that I've finally fixed the problem after printing a few models which had flat sided circles.
I will not be showing my resulting prints for this design. It'll probably also show up any height differences in the central area of the bed surface!