a variant the insulating sheet 32 may not be adhesively bonded to the assembly of the rotor 6 but instead may be adhesively bonded only to each magnetic pole 2 4 in a variant the elementary elements 38 40 may have a different height in order to minimize the quantity of material to be removed during the machining step 68 in another variant the elementary elements may have different heights and each may have a main face 42 which forms a portion of the cylindrical surface so that it is not necessary to machine the main face 56 of the set 37 of elementary elements in another variant the elementary elements may be of a parallelepipedal shape having a main face having a width and length which are equal to those of the magnetic pole but having a height which is less than it in this embodiment the magnetic pole is formed by stacking in accordance with the axis of the rotor of elementary elements advantageously the surrounding insulating sheet 32 may facilitate the mounting of the retaining ring 79 advantageously the method may be applied in order to construct any rotor of a synchronous electrical rotating machine in which it is.