Prusa i3 MK3S/MK3S+ Active Cooler

This is my personal attempt for an active cooler for the extruder motor of the Prusa MK3S/MK3S+. If you print in an enclosure like me, especially in a hot summer day, I'm sure your printer clogged at least one time with PLA filament.

I've tested this for about 3 years on my printer and it's very effective, but every case may be different.

I used another Noctua fan as the original Prusa. You can order it from the Prusa web site. Alternatively you can use every 40mm fan you prefer, but I cannot suggest you a proper way to wire it in that case (pay attention especially to the voltage: Prusa's fan is 5V).

To wire it to the original board I created a custom Y cable and plug it into the hotend fan slot on one end (to be clear, the slot in wich the other 40mm fan is plugged on the board) and to the two 40mm fans on the other two ends (see the picture above). The cable I made is something like the one you see in the image (note that only one end has the yellow wire). If you can't do a custom cable yourself I suggest you to buy a cable like the one in the picture and make yourself the changes needed (if there are any) for the 2 fan cable to fit in.

The yellow wire is responsable for fan check and errors, so Y cable with 2 yellow wire may work too, but I cannot guarantee it. The end with the yellow wire must be connected to the stock hotend fan, the new fan does not need it.

4 M3 screws are needed for the fan. I recommend a length of 12mm, but 10mm or 14mm may work too, again, every case may have different tolerances. For me 10mm is enough, but I feel more comfortable with 12mm. The holes should be just right for the screw to fit. If not be gentle when you screw them in for the first time.

I leaded the cable to the right side of the extruder and merge it into the sleeve with the other wires. Leave a small amount of cable there (as in the photo) so it will be easier take out the whole cooler without screwing out the fan.

The bondtech gears door will open at most at 90°, but if no clogs happen, then I think you don't have to open it so often.

The 40x40mm radiator is not mandatory, but very suggested. On mine there is also a small thermal pad underneath it. It will not cool as much as the fan would do, but it's very aesthetically pleasant in my opinion.

I'll attach to this file the .3mf file for prusaslicer if you wanna use my printing setup and the .stp file I used to create it if you wanna try make some change yourself.

Have a nice print!

Print Settings

Rafts:

Yes

Supports: 

Yes

Resolution:

0.15

Infill: 

50%

Filament: PLA or PETG Black

Notes:

I printed it with as little as possible supports. But you know what your printer can and cannot do, so use as mulch supports as you prefer. Personally I suggest using an overhang threshold of 1°, in this way only the longer bridges will be supported. Also you can add a little support enforcer as seen in the picture.

A brim or a raft is extremely advised. I printed it with 10/15mm brim and it went fine.

You can check all my print settings in the .3mf file. If you don't like my settings feel free to make any changes.

Category: 3D Printer Parts