Prusa i3 MK3S Stepper Motor Cooler Shroud for use with heatsinks

thingiverse

First, massive shoutout to CG-Tech for this design: https://www.thingiverse.com/thing:2975582 My design was inspired by that, but I wanted to include 3 additional aluminium heatsinks to improve cooling even more, so I created my own part from scratch. For 40mm PC fan and 3 40x40x11mm aluminium heatsinks. (Or rather 37x40x11mm heatsinks, see instructions below... that is because the stepper motor is only 38mm deep, at least in my case.) I used these: https://www.amazon.de/gp/product/B07C7SJHTH The design can be printed without supports (at least for me) when positioned bottom up on the print bed. When used with the Noctua 40x40x20 12V PWM fan at full speed, after one hour of printing in an enclosure at 33°C, the stepper motor temp went up to about 40°C. The temperature delta never exceeded 7,5K up to that point and will surely never reach 10K. (For comparison, with the same Noctua fan at the same speed with the shroud-only cooler https://www.thingiverse.com/thing:2975582, the temperature at the bottom of the stepper motor after one hour of printing was around 43°C, the overall delta even increased to about 13K later.) So, with additional heatsinks, it seems one can keep the stepper around 4-5 degrees cooler than without. Of course, depending on your print job, enclosure temps etc., your mileage may vary. Assembly hints: -Preferably each heatsink has 13 fin rows/lamellas by default, because one lamella on each heatsink has to go, so mine were 37x40x11mm with 12 lamellas after preperation (I used an angle grinder, but a fine saw and sandpaper will also do the trick), which is perfect for this shroud. -The remaining 12 fin rows / lamellas will fit in 4 groups of 3 into each pocket between the spacers/"print supports" on the sides of the shroud. Put the left/right heatsinks in first. Firmly push them down towards the bottom all the way. -Now is the last time to get to the fan mounting holes from the inside, so if you have to, add the 40mm fan or any mounting parts now. -Then, insert the top heatsink, watch out for proper positioning right in the center. -Use 1mm thick thermal conductor pads on each heatsink to cover the complete inner surface for better thermal coupling to the stepper motor. -For the left/right heatsinks, apply a folded double-layer strong plasic foil onto the thermal pads as assembling aids. (Thermals pads are too sticky for the shroud to slide onto the stepper otherwise.) -Gently but firmly push the whole shroud from the top onto the stepper. Note that one opening is narrower, thats the front of course. Beware to hold the whole extruder from below, don't break your printer! ;) -When the shroud/heatsink/fan/thermal pad combination is about 90% positioned, pull out the plastic foil assembling aids, afterwards the thermal pads will be quite sticky to the stepper, so don't remove the aids too early. Again, be careful not to inflict damage upon your printer or yourself! -Finally, give the positioning the final detail. Be sure to also push the shroud down again firmly to mold the thermal pads at the top heatsink onto the stepper motor a little. Again, be careful not to inflict damage upon your printer or yourself! -(Fan connection and operation is your own business...) Disclaimer: I don't give any guarantee nor warranty that this design is fit for the described use, or any use at all. I will not be held responsible for any injuries, damage or hazards that may occur during use. Use this design at your own risk! Have fun and enjoy! Cheers.