A modular cutterbar assembly, comprising: a first module having a first edge, a second edge, a top surface, and a coupling side; a second module having a first edge, a second edge, a top surface and a coupling side, the second module coupled to the first module at the respective coupling side; a joint defined between the coupling side of the first module and the coupling side of the second module; a first plane defined by the top surface of both the first and second module (1104, 1108); an internal cavity defined within the first and second module (1104, 1108); a drive transfer mechanism disposed within the internal cavity; a drive hub assembly mechanically coupled to the drive transfer mechanism and extending out of the internal cavity and away from the first plane in each of the first and second module (1104, 1108); a cutting disk having a bowl-shaped form coupled to the drive hub of each of the first and second modules; a coupler mount positioned on each side of the joint and extending from the first plane towards the cutting disk, the coupler mount providing a location to couple the first and second module (1104, 1108) to one another; wherein, a toroidal cavity is partially defined by the first plane, the disk, and the drive hub in each of the first and second module (1104, 1108); further wherein, the coupler mount is disposed at least partially within the toroidal cavity, wherein at least one knife is positioned at a radial edge of the cutting disk, the cutting disk adapted to rotate the knife in a knife plane; characterized in that the coupler mount is at least partially disposed in the knife plane. a first module having a first edge, a second edge, a top surface, and a coupling side; a second module having a first edge, a second edge, a top surface and a coupling side, the second module coupled to the first module at the respective coupling side; a joint defined between the coupling side of the first module and the coupling side of the second module; a first plane defined by the top surface of both the first and second module (1104, 1108); an internal cavity defined within the first and second module (1104, 1108); a drive transfer mechanism disposed within the internal cavity; a drive hub assembly mechanically coupled to the drive transfer mechanism and extending out of the internal cavity and away from the first plane in each of the first and second module (1104, 1108); a cutting disk having a bowl-shaped form coupled to the drive hub of each of the first and second modules; a coupler mount positioned on each side of the joint and extending from the first plane towards the cutting disk, the coupler mount providing a location to couple the first and second module (1104, 1108) to one another; wherein, a toroidal cavity is partially defined by the first plane, the disk, and the drive hub in each of the first and second module (1104, 1108); further wherein, the coupler mount is disposed at least partially within the toroidal cavity, wherein at least one knife is positioned at a radial edge of the cutting disk, the cutting disk adapted to rotate the knife in a knife plane; characterized in that the coupler mount is at least partially disposed in the knife plane.