Prusa i3 MK3 Alternative part cooling duct V2

thingiverse

An update to my previous Prusa MK3 part cooling fan duct (https://www.thingiverse.com/thing:2808683). A great improvement on doing actual cooling, but the nozzle viewing cutout has been dropped - no room for it. The airflow in this model has a much smoother path, starting up in the blower fan rather than just below it. It is split into three channels and smoothly moves the air to a point just below the nozzle. Many part cooling ducts for the Prusa, especially the stock duct, have the airflow hit a large flat surface before forcing the air at a 90° angle. Prusa has brought out a newer duct which angles the blower at 45°, helping a great deal, but I have much better results with this design. Take a look at the last image showing an overhang test (https://www.thingiverse.com/thing:699366) using the stock MK3, the R3 duct at 45°, and this design. Printed with Extrudr's NX PLA, which looks lovely but is awful at overhangs. I've printed this in PETG, ABS, and Onyx (Mark Forged FTW!). So far, even the PETG version has shown no sign of warping. However, I recommend printing in one material better than your usual printing material - i.e., print in PETG if you mainly print PLA, ABS if you mainly print PETG, and Polycarbonate if you print ABS. This works with the current Prusa R3 extruder parts but you will have to mount this without the 45° bracket. See last couple of images. Although the fan will only be held in by one screw, this duct goes up into the fan so it will be secure. Updated version with an arm - I'll be looking into making this duct work with the 45° bracket. Updates ======= Version 31 ------------ * Has a stronger mounting screw block - wider and thicker. * 1.2mm adjustment on the mounting screw to allow for moving the fan lower if your nozzle is lower than normal. * Tweaked the bottom of the custom supports so they print a little easier. Version 32 ------------ * Requested by @yojenh - added an arm to help hold the duct in place. This only works with the Prusa R3 extruder cover. You will need to raid your Prusa spares for an M3 thin square nut and at least an M3x18 screw. * Thickened up the outer side walls for easier printing, and to reduce the witness lines from the internal ducts on the outside walls. * Tweaked the PINDA cutout. I might get rid of it entirely in the next version. * Tided up the original screw block after it had been strengthened. Version 32 and a half ------------ * Small width adjustment to the custom supports to prevent a Slic3r PE bug - Thanks Tony_KrXe! Version 32 and 3 quarters ------------ * Added the Fusion 360 file. Let me know if bits are missing.