Abstract: A tool for mounting a set of helical rods around an elongated central core includes a pair of cartridges mounted opposite each other around the central core, so that the rods extend along the central core. Each cartridge has a first part comprising a through-hole for receiving one of the rods, and a second part comprising a through-hole for receiving another rod, the second part being movable with respect to the first part from an open position to a closed position. In the closed position, the parts form an annular body extending around a central opening for receiving the central core, the cartridge comprising a surface configured to engage with a driving wheel or a driving belt for transfer of torque to the cartridge. In the open position, a gap is provided between the parts so that the central opening is accessible from a position radially outside of the cartridge.