How do I make a tapered leg or column on the rotary axis?

Why a taper needs extra work

A rotary job starts as a straight cylinder. Decoration placed on the surface does not change the body. To get a taper you either model the body or drive the cutter down a slope with a toolpath.

Method 1: model the taper with the zero plane

In the official example a rotary job already has a zero plane component (use Create Zero Plane if yours does not). Tilting it makes the body.

1. Double-click the zero plane component to open Component Properties.
2. Enter a Base Height (the official example uses 0.8).
3. Tick Tilt, click Set, then in the 2D view click the middle of one end and the middle of the other.
4. Enter the angle (3 degrees in the official example).
5. Open Material Setup and lower the slider until Gap Inside Model reads 0, so the body is measured from the center of the cylinder.
6. Cut with a 3D Roughing Toolpath, then a 3D Finishing Toolpath.

Method 2: sloped toolpath

A published tutorial tapers a blank with the Fluting Toolpath alone:

1. Fill the job with parallel lines running along the length. The count is the circumference divided by the bit's stepover. Their example: a 3.5 inch blank and a 1 inch ball nose at 0.1 inch stepover needs 110 lines.
2. Use the flute style that ramps over the whole length of the line.
3. Flute depth is half the diameter change. Going from 3.5 inch to 2.5 inch needs 0.5 inch.
4. A linear ramp gives a straight taper, a smooth ramp gives a curved one.

Limits to know

• Wrapped toolpaths match the flat design only at the surface of the blank. The closer to the axis, the more the path is squeezed around the cylinder.
• Clipart on the thin end comes out narrower than drawn. Stretch it along the wrapped direction to compensate.
• Where diameters differ a lot, draw boundaries around each region and calculate separate toolpaths with settings suited to each.

Pro tips

• Put the thick end of the leg at the motor end so the thin end is not twisted by the drive.
• Leave a straight, full-size section at each end for holding (see the entry on planning chuck and tailstock clearance).
• Example values in the sources are illustrations. Test your depth and stepover on scrap.