Why won't my rotary job carve under the overhangs? (Rotary can't do undercuts)

Why this happens

The software's rotary machining is a wrapped 3-axis model: it machines a flat relief that gets wrapped around the cylinder, and the tool always points at the rotation axis. The official documentation states that the software does not support 4-axis machining: the tool moves along the rotation axis and in Z, but it cannot move in the wrapped dimension. That means undercuts are geometrically impossible. Any surface that faces away from the tool (overhangs, undersides of protruding details, hollows behind features) cannot be reached. This isn't a setting; it's how wrapped rotary works. True undercutting needs simultaneous multi-axis machining, which the software does not do.

Your options

1. Design without undercuts. Keep every surface visible from outside the cylinder (radially). Most spindles, columns, and table legs are naturally undercut-free.
2. Split the work into double-sided flat machining. Carve two halves face-down and face-up and glue them, for figures that genuinely need undercuts.
3. Move to multi-axis CAM (for example, Fusion 360 or DeskProto) with a machine that supports simultaneous 4-axis, outside this software's workflow.
4. Hand-carve the undercuts after the machine roughs everything reachable, the traditional sculptor's hybrid.

Pro tips

• Check for accidental undercuts before cutting: examine the model silhouette from the axis. Anything hidden behind another surface radially won't machine.
• A slight taper on "vertical" faces (a few degrees of draft) avoids near-undercut walls that leave fuzzy uncut slivers.