File Format

To submit a file for additive manufacture the format must be STL. STL is a generic, faceted surface model created from datapoints on the approximate surface of the original part originally created for STereoLithograpy.

Since all surfaces will be broken into triangular facets the actual location of the sufaces will be dependent number of points used to to create the faceted surface. When you are creating an STL file you can control the chord height –

Chord Height Image

Varying the chord height will allow the variation of the size of facets in the generated file. A smaller chord height will bring the facets closer to the actual, modeled surface. This will create smaller facets and a larger number of facets resulting in a larger file.

 For example, a sphere saved to STL will have a coarse surface with a large chord height:  Coarse Surface
And the same sphere will have a smoother surface with a smaller chord height: Smooth Surface