Occasionally Powermill will import models at the export tolerance or import the models at a low resolution tolerance an you will receive the following error. 

 

The model will still import however the surfaces look bad. 


To fix this issue. Set the View, Appearance, Model Drawing options to a tighter tolerance. this will fix the gaps in the models shading tolerance. Note that graphics performance may be effected depending on the model size and your system. This can happen in vary large files.