GROUP SIX offers NSB ball splines available as economy, precision, rotary ball splines or super bush splines, some with hollow shaft options. Rolling surfaces of balls under load have semicircular grooves and each size has either three 3 groves or six 6 groves. This portion is ground with high accuracy after heat treatment, then finished by lapping. Thus this mechanism has high load carrying capacity, and smooth and stable starting action is possible. Formulas for calculating ball spline ratings are available in our catalog. Call 800-433-3434