A fan for NEMA 14 stepper motors that can be placed on the exposed end shaft. For part types NEMA 14 SYS35ST36-1004B as used for example on the RepRap Pro Huxley 1) Calibrate your printer for dimensions 2) Print STL 3) REAM to 5.0 mm (my printer made it at 4.9X mm) http://en.wikipedia.org/wiki/Reamer 4) Fit printed fan Excessive axial force should not be used, the aim is a light interfernce fit i.e. snug 5) Fit fan cover (safety first ;-) ) http://www.thingiverse.com/thing:22726Sample Part Manufacturing Technical Documentation Printer : Huxley (RepRap Pro) Software : RepRap Pro Software 811708f - Pronterface Material : PLA - Faberdashery - Arctic White Material Dia.: 1.75 mm (Msd 1.79 mm ) Nozzle : 0.4 mm Layer height : 0.3 mm Layer width : 0.6 mm Extrusion T : 200 C Bed T : 60 C Feed Rate : 28 mm/s Perimter rat.: 0.5 Cooling Fan : NoDesign For Manufacture Parameters Model : Absolute dimensions Scale : 1:1 Holes : Ream for fit Layer height : 0.3 mm Layer width : 0.6 mm