Abstract: A device for continuously forming a heat exchanger that has a helically wound fin tube coil formed by a plurality of wraps includes a rotationally driven mandrel with a central axis and a plurality of forming corners equiangularly disposed about and displaced from the central axis. The rotation of the mandrel is about the central axis in order to wind the fin tube coils onto the mandrel. A forming block is operably rotationally coupled to the mandrel and rotates with the mandrel. The forming block is also slideably engaged with the mandrel for axial translation a selected distance with respect to the mandrel. The forming block guides the winding of the fin tub coils onto the mandrel. An actuator is operably coupled to the forming block and causes the axial translation of the forming block.