A turbomachine assembly is shown, including a rotor and a ring of blades mounted on the rotor. Each blade includes an airfoil portion and a root portion inserted in a circumferential blade-retaining groove of the rotor. The blade-retaining groove includes an enlarged groove portion. The blades in the enlarged groove portion are rotatable around a respective, generally radial axis, to take a position of minimum tangential dimension. At least one removable insert is arranged along the enlarged groove portion, between the root portions of the blades located in the enlarged groove portion and a side wall of the blade-retaining groove, to force and lock the blades in a final assembled arrangement.