I have been interested in the fourth axis and lathe part of SC so I downloaded your project file just to see how you set up for lathe.
I got to looking at your part was wondering if it is the way the geometry of that arc was created. I tried to duplicate that section of your part in solid works and tried to make that arc with a segment of the circle at a 1.245 R, and as just two lines from edge to center point of the perimeter of the arch.
The former (see attached Follower Test 1 screen caps) method resulted in a wider interference cut but not as deep (only .005 rather than .012) and the latter (see attached Follower Test 2 screen caps) method resulting in no interference it seems.
You might be able play with the solid geometry or how you created it in your CAD. But that's weird how SC doesn't follow the geometry for the convex profile.
Gerry, who's glancing over at his 10X22 lathe and wondering how to CNC it (chair)
Currently using SC7 Build 1.6 Rev. 64105