Curves that become segments

Francesco Perusi

I have always had this issue, basically when i draw a nurbs curve or a circle, i see it perfectly rounded, but once i cut this curve into a solid object, the cut results as a "segmented" curve.

To explain better: If i make a circle of 30mm of diameter, when i cut it into a solid cube, the hole will not be perfectly rounded but seems like a polygon with lots of sides, this results in a smaller diameter (like 29.5) due to all the segments. When i 3D print holes, the diameter is always smaller and the effect is ugly because the surface is not smooth but full of little "faces"

As you can see the surface is not smooth but "edgy" and the circle becomes a polygon.