How do I cut coves, rings and a parting cut around a cylinder using only 2D toolpaths?

The idea

A straight line drawn across the wrapped axis becomes a full ring around the cylinder. Run a Profile Toolpath along that line and the blank turns under the bit, like a lathe cut. The shape of the bit becomes the shape of the groove: a ball nose makes a cove, a V-bit a V groove, an end mill a flat-bottomed step.

Steps for a ring or cove

1. Turn snapping on. With Draw Line/Polyline, draw a line along the wrapped axis from one wrapped boundary to the other (the two job edges that meet on the real part). The official example places one 1 inch in from each end.
2. Select the line and open the Profile Toolpath.
3. Choose the bit for the groove shape and enter the cut depth.
4. Calculate, then run Preview Toolpaths. The animation plays flat and switches to the wrapped view when it finishes.

Steps for a parting cut that leaves a tab

1. If the design fills the job, open Job Setup and add length (the official example adds 2 inches), press F9 to re-center the vectors, and recalculate the existing toolpaths.
2. Draw a ring line at each end, the same way as a cove.
3. Create a Profile Toolpath with an end mill. In Cut Depth type z-0.25. The letter z stands for the blank radius, so this stops 0.25 inch short of the center and leaves a tab 0.5 inch in diameter.
4. Pick Machine Vectors Outside/Right or Inside/Left so the width of the cutter falls on the waste side, not on your part.
5. Saw through the tab off the machine.

Pro tips

• The official guide stresses that its tool sizes and tab diameter are only illustrations. Size the tab for your wood, blank length and machine. As general shop advice, a tab that is too thin can twist off while the cut is still running.
• Shop practice, not from the official guide: cut the parting grooves last, after all detail work, so the part stays stiff as long as possible.
• Several rings at different depths with different bits build a turned-looking profile quickly. For flutes between them see the entry on the Fluting Toolpath.