Sorry that wouldn't work for you :-(
The circular ribbon was present in the file you sent me along with a couple of other artifacts, I had to unstitch the ribbon from the solid and delete it, I suspect the other grey artifacts were also present but were dealt with by BobCAD's cleanup tools.
Althoug the CAD side isn't to everyone's taste, even in V25 Bob's CAM had some very powerful 2, 3 and 4 axis toolpath options,
Regards,
Nick