A stationary bowl of the apparatus has a bottom wall, and the upright drive shaft of a motor located beneath the bottom wall extends through the same and into the interior of the bowl. A tubular member surrounds the drive shaft out of contact with the same; the other open end of the tubular member is downwardly spaced from the upper end of the drive shaft and the lower end of the tubular member is welded to a tubular collar of a support ring located beneath the bottom wall and extending into the interior of the bowl through the bottom wall outside the tubular member. A second tubular member is placed from above over the shaft and the first tubular member, surrounding the first tubular member with clearance. Cooperating engaging portions at the upper end of the shaft and within the second tubular member engage one another so as to connect the second tubular member with the shaft for joint rotation. The lower end portion of the second tubular member is formed or provided with transversely projecting tool portions, such as comminuting or mixing blades.