Abstract: An adjustable drill is provided comprising a drill body having at least one face surface with a plurality of serrations provided therewith. The drill further has at least one cartridge having a cooperating plurality of second serrations, to be driven with the drill body when assembled therewith. The at least one cartridge includes at least one insert pocket, and at least one insert is releasably affixed in the insert pocket provided in the cartridge. In further examples, the adjustable drill may have a central cutting system in combination with the adjustable cartridge type system, wherein the central cutting system may be modular. There may also be provided a modular type of holder arrangement to provide flexibility to adapt the system for various applications.