Indexed rotation adds a turntable/lathe A axis to your machine, so you can cut one face, rotate the foam, and cut the next. By building a shape from several rotated ruled-surface passes, you can make parts that a single straight wire can never reach — hexagonal columns, multi-face carvings, rotationally symmetric forms.
Enabling it
Set Machine type to 3-axis (X/Y + ROT) or 5-axis (X/Y + U/V + ROT) in Settings. A Rotation axis (A) panel appears with:
- ROT position — horizontal (lathe, axis along the wire/length) or vertical (turntable).
- Reverse axis — mirror which end the motor sits on.
- Rotation — CW or CCW spin direction.
- Offsets — where the axis sits in machine coordinates, with a Center rot button to put it at the envelope centre.
The 3D scene draws a red motor cube on a boundary plane and a dashed axis line so you can see where the foam will spin.
Centering the foam on the axis
For the foam to spin in place (rather than orbit), its centre must sit on the rotation axis. Use Center on rot. axis in the Material block panel to move the block onto the axis automatically.
Building an indexed cut
In ＋ Load parts, a Rotation tab appears on rotation machines. It is a table of up to 12 stages, each with:
- a shape (the profile to cut at that stage),
- an angle to rotate the foam after that cut, and
- a times count to repeat the (cut, rotate) pair.
For example, a square profile with a 60° angle repeated 6 times shaves six flats around the foam to make a hexagonal column. Press Generate cut and the tool plans a stacked sequence of cuts with A-axis rotation commands between them.
The solid carve
cncfoam.com models the foam as a real solid. Each stage subtracts (or, on plain cuts, keeps) the cut shape from the stock using boolean (CSG) operations, then bakes the rotation into the foam so the next stage cuts the already-carved, rotated block. You watch the part build up stage by stage, with the foam physically spinning between cuts at your chosen Rot. rate (°/s).
The G-code
The output is a stack of cuts with A<degrees> rotation commands inserted between stages, ready for a controller with a rotary axis. See Multi-axis G-code.