Fan inlet intake noise reducer

thingiverse

This duct reduces inlet turbulence at the fan blade tips, thereby reducing high-frequency fan noise. March 2020: I added several wall duct thickness STL files, plus one file with a flat bottom edge/side, in case you have a heated bed that melts the duct issue (I've got the T-shirt). With a heated bed over 50C, you should consider printing in ABS or PC. The additional wall thickness files are because some slicers struggle to slice very thin walls. Test which STL file works with your slicer. The Cetus mk2 with extruder V2 has a 40mm square x 10mm thick 11CFM cooling fan spinning at 9500rpm. Any turbulence causes an unpleasant high-frequency whine. Even the wire fan-blade finger guard generates the whine. The fan exhaust side is less important but should still be addressed. Reducing noise also tends to increase airflow, making it a win-win situation. These ducts are thin-walled. I printed using a 0.1mm layer, 0.4mm nozzle, and a track (paving) width of 0.3mm. It takes less than an hour to print, and it's half the weight of the original wire fan guard. The thin inlet cone is slightly flexible, so I had to put the bolts through the 4 mounting holes by slightly deflecting the cone and mounting the duct with the bolts as an assembly. You can increase bolt clearance by vertically scaling in the slicer before printing. I designed three versions. The center cone style is slightly noisier but provides some finger protection. I suspect the three radial cone supports create a small amount of turbulence. The fan gasket increases the blade clearance on the exhaust side, further reducing fan noise on my Cetus. On other printers, it's a simple quick test to scale the Z dimension in the slicer for a thicker or thinner gasket. My conclusion is that this mod is effective. The steppers are now far louder than the fan. The dominant noise from the fan is quiet white noise. Designed in Fusion 360 and printed on my modded Cetus. Have fun - Peter