Method for manufacturing, using the lost-wax casting method, a metal component made from nickel alloy, with a columnar or monocrystalline structure with at least one elongate-shaped cavity, comprising the following steps of: producing a wax model of the component with a ceramic core corresponding to said cavity, the ceramic core comprising a first holding span at a longitudinal end and a second holding span at the opposite end, the second span comprising surfaces that are parallel to the direction of propagation of the cooling and surfaces that are not parallel to the direction of propagation of the cooling, producing a shell mould around the model, the shell mould comprising a base and the first span of the core being on the same side as the base of the shell mould, eliminating the wax by dewaxing the shell mould, placing the shell mould in a furnace, the base being placed on the hearth of the furnace, pouring a molten alloy into the shell mould, carrying out a directed solidification of the poured metal by gradual cooling from the hearth in a propagation direction, the surfaces of the second span that are not parallel to the direction of propagation of the cooling being covered initially by a deposit of wax, characterized in that the core is secured to the shell mould by an anchor between the first span of the core and the wall of the shell mould, the second span of the core being held in the shell mould by a holding means sliding over the wall of the shell mould, said sliding holding means comprising a layer of varnish applied, before the production of the shell mould, to the surfaces of the second span that are parallel to the direction of propagation of the cooling and that are not covered with wax, the surfaces of the second span that are parallel to the direction of propagation of the cooling and that are not covered with wax and that, after formation of the shell mould, comes into direct contact with the internal wall of the mould, being initially fully covered with said layer of varnish, the layer of varnish having a thickness of between 3 and 5 hundredths of a millimetre, said layer of varnish being eliminated during the operation of dewaxing the shell mould, as well as the wax covering the surfaces of the second span that are not parallel to the direction of propagation of the cooling, so that a free space (17, 18) is created between the second span of the core and the wall of the shell mould, said free space (17, 18) created being maintained during the progression of the directed solidification, so as to prevent the second span of the core from coming into contact with the wall of the shell mould when the core expands. producing a wax model of the component with a ceramic core corresponding to said cavity, the ceramic core comprising a first holding span at a longitudinal end and a second holding span at the opposite end, the second span comprising surfaces that are parallel to the direction of propagation of the cooling and surfaces that are not parallel to the direction of propagation of the cooling, producing a shell mould around the model, the shell mould comprising a base and the first span of the core being on the same side as the base of the shell mould, eliminating the wax by dewaxing the shell mould, placing the shell mould in a furnace, the base being placed on the hearth of the furnace, pouring a molten alloy into the shell mould, carrying out a directed solidification of the poured metal by gradual cooling from the hearth in a propagation direction, the surfaces of the second span that are not parallel to the direction of propagation of the cooling being covered initially by a deposit of wax, characterized in that the core is secured to the shell mould by an anchor between the first span of the core and the wall of the shell mould, the second span of the core being held in the shell mould by a holding means sliding over the wall of the shell mould, said sliding holding means comprising a layer of varnish applied, before the production of the shell mould, to the surfaces of the second span that are parallel to the direction of propagation of the cooling and that are not covered with wax, the surfaces of the second span that are parallel to the direction of propagation of the cooling and that are not covered with wax and that, after formation of the shell mould, comes into direct contact with the internal wall of the mould, being initially fully covered with said layer of varnish, the layer of varnish having a thickness of between 3 and 5 hundredths of a millimetre, said layer of varnish being eliminated during the operation of dewaxing the shell mould, as well as the wax covering the surfaces of the second span that are not parallel to the direction of propagation of the cooling, so that a free space (17, 18) is created between the second span of the core and the wall of the shell mould, said free space (17, 18) created being maintained during the progression of the directed solidification, so as to prevent the second span of the core from coming into contact with the wall of the shell mould when the core expands.