The Brush > Orientation sub-palette controls the degree and extent of spin for the brush.
SpinCenter
The SpinCenter will control the amount of distance the alpha will spin from the center of the brush. The higher the slider the larger the arches will be.
SpinAngle
The SpinAngle will control the amount of distance the alpha will spin from the center of the brush. The higher the slider the larger the arches will be.
SpinRate
The SpinRate will control the amount of spins to the selected alpha. A high setting will cause the alpha to spin more often.
Reference Guide > Brush> Orientation