A steel plug-and-feather splitting system consisting of a tapered wedge inserted between two semicircular feathers placed in a drilled hole.
Cuneo alettato is a steel splitting device used during roughing. A series of holes is drilled along the intended break line. Two semicircular feathers are inserted into each hole, and a tapered steel wedge is driven between them until the stone splits.
Etymology
Italian: cuneo, “wedge,” + alettato, “fitted with wings or feathers.”
Sculptor Notes
The feathers spread the force of the central wedge against the sides of the drilled hole. A row of correctly aligned sets can produce a remarkably controlled fracture through a large block.
References
https://levocidelmarmo.sns.it/scheda_oggetti_relazione.php?denom=cuneo+alettato&id=18