A method of making a rotor assembly for an electric motor by adding bars made out of a conducting material such as copper, to spaces between the teeth of a stack of discs, inserting bars referred to as “slugs”, also made out of a conducting material such as copper, in the spaces between the bars on either side of the stack of discs, radially compressing the bars and discs, one or both of which are plated or otherwise coated with a braising material, and then heating the rotor to allow the bars to be braised to the slugs.