loopacrylics wrote:I had a similar question regarding roughing pass. I’m going to be making a fairly large 3D model out of 2 inch cast acrylic. I have a half inch ball nose, or a half inch end mill for roughing. Would I want to use the ball nose for this? Or is it the same answer as above?
On some materials it may make a difference.
When an end mill is roughing it is cutting on the circumference of the tool.
The same is true of a ball nose, the only difference is that the "circumference" becomes smaller closer to the tip. Essentially the machine cannot go fast enough at the tip to produce a decent chip load. That may cause heat near the tip.
Of course, the same is true when doing the finishing with a ball nose mill.
As my old machinist boss told me all those years ago: "Tools do not want to cut on the point, instead they push."