multiple rescaling of path while keeping fixed space and fixed stroke

Hi!

I'm trying to screat guilloche pattern. i have path and I want to do "transforn each" inorder to copy and rescale it 500 times. 

I know how to keep fixed stroke.

but no matter what I de... the distance betwwen each scaled copy get bigger by pressent.

I want each copy to be exact 0.5mm from the next one.

any idea?

thanks!