37 a is preferably constant for example at 30 u00b0 to provide a desired pressure to the paper pulp stock or other materials being mixed by contact with the vane face 37 a of the vane 37 upon rotation the vane 37 may be slid onto the spar stub 38 see fig5 in order to align the spar stub mounting surface 37 c of the vane 37 so that the corresponding attachment devices are aligned to secure the vane 37 to the spar stub 38 and the innermost vane surface 37 d abuts the spar ring 36 fig4 the outermost vane surface 37 e of the vane 37 is generally curved from the vane face 37 a to the trailing edge 37 b the interface of the trailing edge 37 b and outermost vane surface 37 e of the vane 37 provides a lifting effect that sucks fiber off from the stock or other materials being mixed by rotation of the rotor 35 note also in fig7 that the trailing edge of the vane comprises a curved edge 116 radiused downwardly toward the bed plate surface this too helps to provide a suction pulse that cleans the bed plate further protruding end dam member 114 is provided along the o d extremity of the trailing edge the end dam doesn 39 t allow flow to u201c leak u201d off the end of the rotor thereby improving suction and bed plate cleaning across the entire swept area fig8 shows generally according to the various exemplary embodiments of the invention a configuration of the vanes.