[Ithink]

Has anyone experience how to polish 'ribbed' surface on moulds.
Regardless the precision of our machine, and well adjusted spindel all flat surfaces are still optically "ribbed".
Do you beleive that there are abrasive tools non-dangerous for spindel?

[Torsten]

Yup, there is a way.
You are probably not gone like it, but polishing molds is still done mostly by handwork.

[bugzpulverizer]

This is just a shot in the dark, but I used to have what looked like perpendicular to the cut rib problems with 3-D contour milling. If that made sense. What I found out was that basically it was caused by the program spitting out splines instead of arcs. Try increasing filter on your cad software. It might help.