Airfoil Fan Grill Guard 40mm Quiet SCAD

thingiverse

I replaced the hot end fan on my Ender 3 with a MF40202V2-1000U-A99 (Digikey 259-1801-ND), and put a cheap fan grill on it I picked up at the same time. The fan made a whining noise, and after some messing around, I discovered it was the fan grill causing the noise due to the turbulence it caused, mostly around the edges of the fan (see [1]). Therefore, I designed this one in an attempt to create a grill that minimized the turbulence caused by its presence. For more information and some testing on fan grill noise, see [2]. The inlet bell is radial (see [1]). The spoke supports are airfoils. A portion of airfoil sits in front of the hub of the fan, and the rear grill provides the tail of this airfoil to "zip" the air back together, though I will admit this tail section is likely mostly ineffective. The airfoils are symmetrical NACA airfoils (see [3]). If making adjustments to the SCAD file, there is a balancing act of minimizing the width/thickness of the tail of the support airfoils (ideally this thickness would be zero) while still providing enough thickness to cause the slicer to print one line so there will be contact with the build plate and no need for supports. This tail thickness is given by `supportTailWidth`, and should probably be set to the line width being used in the slicer. There is also some playing with dimensions to get the airfoils for the fan hub to come out to the right size for your application, see `coneHeight`, `tailLength`, and `fanHubDiameter`. Also check that `holeDistance` and `holeDiameter` match your fan and needs, but I think these should be fairly standard. [1] https://www.mayafans.com/fan-stack-fan-ring-or-fan-cylinder.html [2] https://www.pugetsystems.com/labs/articles/Effects-of-Grill-Patterns-on-Fan-Performance-Noise-107/ [3] https://en.wikipedia.org/wiki/NACA_airfoil#Equation_for_a_symmetrical_4-digit_NACA_airfoil