Abstract: In a key apparatus having a drive keyway, the drive keyway comprises, a first side wall having a planar inner surface, a second side wall having a planar inner surface, and an end wall having a curvilinear "wave-shaped" inner surface. The first and second side walls are spaced apart, and connected to and extend generally transverse the end wall. The configuration of the drive keyway is very helpful in reducing stress concentration in the gear, and minimizing any motion of the drive key in the axial direction. The present invention is particularly useful in making powdered metal gears for gear pumps, such as hydraulic gear pumps.