With cambam it's very easy to face off round bar stock (held vertically) by using the pocket method. This produces a nice spiral from inside to outside.
But to cut down the vibration of the tool entering the piece, I'd like to use a nice spiral from the outside to in. Starting the spiral from outside the round face and entering from outside.

How can I acheive this? I have the outside to inside part kludged by using a 0.1mm circle which I'm profiling using a 15mm cut width and negative roughing clearance. But it's concentric circles with a straight move in between each which impacts surface finish. I'd prefer to have an ever decreasing spiral.