A modification of the standard MK3 Fan Shroud to allow mounting of a second blower, for extra cooling power.
N.B. The second fan does not need to be a "three wire" type - simply join the red/black wires of your new fan to the red/black wires of the existing Prusa fan, and you're ready to go.
17/Jun/2019 - https://www.thingiverse.com/thing:3697665/ - The wonderful RosyRL pulled together a remix that makes this design compatible with the MK3S - go download from this page if that's your printer!
31/Mar/2018 - Added 'Bondtech Volcano QuickFix' version
This is in response to a specific community request for a volcano compatible version for Bondtech Extruder body. This is a quick 'remix' style edit, where I have moved the mounting holes up 11.5mm (I hope this is correct - testing required!), without making any changes to the flow paths. The extra space available in a Volcano setup would allow much more open channels and sweeping paths, and I would like to improve the Volcano version in future, but this will require significant modelling work which I just don't have time for at the moment, I'm afraid :(
17/Jan/2019 - Added Bondtech and Vekoj Compatible versions
WP12.1 - Major overhaul to the nozzle design. The 'mini' nozzles were too small to let much air through, and got too close to the heatblock for high temperature printing. Making them bigger wasn't an option, so I've removed them entirely and re-optimised for two larger outlets. As always, testing/feedback appreciated - performance is getting better every time :D
WP11.3 - Added a bit more clearance around the Heat Block, as R3 users were reporting interference.
Following user testing, I've iterated the outlets further, and am now much happier with the overall cooling performance.
I found that the rear left nozzle interfered very slightly with the red cable to my heater block, but I simply added a bit of slack to this by loosening the cable ties on the back of the extruder body, and have not had any issues since.
Other tweaks e.g. thicker walls at the nuts, reduced fillets for printability etc. also implemented, but it's the airflow updates that are key.
I wasn't happy with the actual shroud design from Prusa, so rather than simply allowing you to fit a second fan, this new version offers drastically redesigned airflow paths, including a completely clear view of the nozzle, for faultfinding and mindless gazing.
This is still a work-in-progress, and may be tweaked in the future, but early results are positive for true 'all around' cooling, at high speeds.
This prints OK without supports - the worst you'll get is a dangly from the first layer of the bridge, but the print will complete OK and you can just trim it. I got this on my first test-print, but it printed perfectly on subsequent prints, with the prototype of this shroud doing the cooling!
Old version left online for posterity, or in case people prefer it.
V3 is drop-in replacement for R2 body, and V5 is drop-in for R3.
N.B. Updates in the works, coming soon!
For the R2 Extruder body, this does not require any modifications to other components, simply swap out the shroud.
V2 Updated to separate fans to Left/Right sides of shroud, improving balance of flow.
V3 Updated to increase wall thickness on Nut Holders (since printing orientation is different from Prusa Nut Holder). Optimised for 0.4mm Nozzle. Removed requirement for 1mm spacers behind existing fan.
V4 Updated to incorporate the July 2018 Redesigned Shroud released by Prusa. This has different outlet positions, which may improve things - although I have not tested this - feedback appreciated! I'm leaving V3 available for download because of this. Fans not angled to 45deg as this would cause problems with the split airflow path, and may not be necessary since there is double the air pressure in this design, so the reduced bend radius will not provide as much of a benefit as it will to a single-fan design. That said, I intend to produce a 45deg version to allow airflow into the extra vent on the extruder body.
V5 - Added extra clearance for Noctua Fan on R3 Exturder Body.
You may find this: https://www.thingiverse.com/thing:3032939 useful if you want the arm back, while keeping the R3 ducting.