could alternatively be provided also in the preferred embodiment the interfering portions 28a 28d comprise flat surfaces which are equally spaced and separated from one another by curved wall portions 30a 30d still further in accordance with the preferred embodiment inner surfaces of 31a 31d of the curved wall portions 30a 30d lie on a common inside radius and the flat surfaces 28a 28d lie inside the common inside radius the sleeve 24 also includes an outer surface 32 which in the preferred embodiment is substantially circular cylindrical in shape an outer diameter of the outer surface 32 is preferably slightly less than an inner diameter 34 fig4 of the aligned bores of the lamination stack 20 during assembly the central bores and winding slots of the laminations forming the stack 20 are aligned and the sleeve 24 is inserted into the aligned bores preferably the outer diameter of the sleeve 24 is sufficiently close to the inner diameter 34 of the lamination stack 20 so that the lamination stack 20 is loosely held in place on the sleeve 24 at the desired location thereafter the shaft 12 is pressed into the sleeve until the shaft 12 is located at the desired position therein fig5 illustrates the deformation of the sleeve 24 after the shaft 12 has been inserted therein whereby compressed fiberglass material in the vicinity of one of the flat surfaces for example the flat surface 28a flows into voids between the curved wall portions 30 and an outer surface 40 of the shaft 12 preferably the.