1.667 x 3.14159 = 5.23703 / 6 = .872838 Linear distance per motor revolution
200 step motor x 10 microstep (or whatever it is) = 2000 step per rev.
2000 / .872838 = 229.13759 steps per unit........or there abouts.
I think
What are your available microsteps ?
Some are 1/2, 1/4, 1/8, 1/16 and some are 10......plus others.