The aim the disclosed process is to ensure maximum precision both at the level of the manufacturing of an electronic assembly from a chip with small dimensions as well as the level of the placement of such an assembly on an insulating substrate. The weight-training apparatus has longitudinally opposing ends, each of the ends having longitudinally outer and inner groups of weight plates. The pockets are elongated in the direction between the opposite sides of the body, and said body is rollable in the direction between the opposite ends to form a roll enclosing said pockets and which roll can be releasably held in the rolled condition by suitable fasteners. The bearing shaft is mounted in a pair of spaced rubber bushings to absorb vibration and reduce noise. or higher and lower than 800\xb0 C. The first cartridge further includes a third operating portion.