Insert adaptor for parting off

An insert adaptor for parting off having an adaptor index axis, the insert adapter being made of metal and comprising:

• parallel adaptor first and second sides which are connected by an adaptor peripheral surface which extends peripherally around the adaptor;
• the adaptor index axis (IA) extending through the center of the first and second sides;
• an adaptor thickness (AT) measured between the first and second sides, in a direction parallel to the adaptor index axis (IA);
• a plurality of pockets formed about the adaptor peripheral surface, each pocket configured for resilient clamping;
• and
• a fastening configuration comprising a plurality of screw holes opening out to the first and second sides for clamping the insert adaptor to a tool;
• wherein:
• the pockets are equally circumferentially spaced about the adaptor peripheral surface relative to the adaptor index axis (IA);
• the adaptor peripheral surface comprises a straight bearing surface extending between each pair of circumferentially adjacent pockets;
• in a side view of the insert adaptor, each straight bearing surface comprises a recessed portion located adjacent to one of the pockets, a non-recessed portion, and a transition portion connecting the recessed and non-recessed portion;
• and
• the insert adaptor has a material volume of greater than 50% of an imaginary cylinder encompassing the insert adaptor, the imaginary cylinder being a right-circular cylinder having a cylinder axis coincident with the adaptor index axis (IA), and a cylinder height equal to the adaptor thickness.