You can use the Fluting toolpath in PartWorks or VCarve to control Z height along a toolpath.
Aspire would allow you to design the profile using a 2 rail sweep.
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Another thought is to move in the X and Y with a constant Z height by cutting the side rather than the top of the rotating material.
Theoretically you could mount a regular lathe on your table.
The material is spinning at a constant velocity
The bit is on the left or the right of the material and the Z height positions the end of the bit below the center of the material
As the bit gradually moves towards the material it beings cutting.
You control the profile by moving into/away from the material
You would need to be careful to to move too far into the material so multiple passes may be required
I have NOT tried this.
- Randall Newcomb
10 fingers in, 10 fingers out
another good day in the shop