General Purpose Series These Aluminium Fan Blades are fabricated of 22 gauge aluminium alloy, and are available for 3/16", 1/4" and 5/16" diameter motor shafts. Blade hubs have slotted set screw for easy assembly to motor shaft. Sizes range from 4" to 10" in diameter. Each fan blade size is available in either clockwise or counterclockwise configuration. Rotation is determined by facing air discharge. All Aluminium alloy models are four or five blade design for light weight and reduction of vibration. Fan Blade Rotation To Determine Blade Rotation CW — Clockwise CCW — Counter Clockwise A. Lay blade on flat surface (either side up). B. Direction of rotation is determined by observing which blade edge touches the flat surface.