The smaller mill does not make smoother features.
The smaller mill allows you to make smaller features than a mill which is wider than the feature.
With fixed parallel stepovers (raster output), the smaller mill leaves a bigger cusp as it climbs vertically. This can be reduced by using smaller steps and extending the milling time. However, even if you reduced the stepover by half, the cusps on nonhorizontal surfaces will always be present just reduced. And they will always be smaller if you use a larger mill.
In short choose the largest mill that can still render the features. In some cases it makes sense to do a tool change to render just the fine features with a smaller mill. |