Abstract: A shaft (6) extending from a motor housing (1) of the mixer terminates in an end portion (10) which, for easy attachment of a mixing head (H) thereto, is formed with a shallow circumferential groove (18). This permits fitting a hub or sleeve (13) on the mixing head (H) onto the end portion (10) of the shaft with axial misalignment, without exerting lateral bending forces on the hub (13). The head is formed with a resiliently deflectable tab or flap (15) for frictional engagement with the shaft, to hold the head in secure axial position on the shaft. The terminal end (19) of the shaft (6) is convex and rounded, or essentially part ball-shaped or part-spherical. Preferably, a guide ring or guide surface (23), having the diameter of the shaft, is positioned between the circumferential or ring-shaped groove (18) and the convex and rounded, or part spherical ball-shaped or part end (19). The groove (18) is shallow, wider than deep, and preferably, in cross section, part-circular.