Semi-Circular Anet A8 Fan Duct

by lokster, published

Semi-Circular Anet A8 Fan Duct by lokster Dec 9, 2016
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If you use this fan duct & think it makes your prints look better, don't forget to TIP! ;)

This is my version of the "circular fan duct" for the Anet A8 printer (and other compatible printers).

  • it's actually semi-circular. The circular one deforms after a while if printed in PLA (and I use/have only PLA), so I designed this version.
  • it snaps to the fan a lot more securely (on the outside of the fan), and there is no chance of falling off during print.
  • designed in such way, that the air blows just below the tip of the nozzle. The original design was blowing too far down.

Designed in Blender, by heavily modifying http://www.thingiverse.com/thing:1874390 - simplifying the mesh, adding the new attachment part etc.

Note: there is newer, and more effective fan duct I designed: http://www.thingiverse.com/thing:2133328

Print Settings


Anet A8







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love this thing. If anyone is having a problem where their filament will randomly get reversed out of the extruder then your printer will try to start extruding again and print without extruding I found that the solution is printing with the SD card and not the cable straight to the computer. No idea why this fixed my issue, but it did. Also try reducing your retraction distance to 2.5mm.

Awesome work. I had the full circle version and it fell off twice during prints, Extruder nozzle melted a huge hole in it.

Comments deleted.

I'm having the cooling problems a lot of people are talking about. I've not gotten in to the modeling side of things quite yet - I want to get the slicer/printer thing down first, doing upgrades others have taken time to craft. Mosfets are in the mail on their way

A few things I see to suggest repair:
Moving the nozzle "up" in the extruder by tightening the threads up. Then reset Z height.
Slide the nozzle "down" on the fan and clamp in place with the screws.
Make a taller version from this model in fusion360

This thing is definitely worth it, although it took me a second to figure out how to mount it on the fan because the one I used before went inside of the fan output instead of on top of it like this one.

Works great. It was my first print and 2nd. The first broke loose of the bed 3/4 through. Printed the second with a raft. But since I installed this (and leveled the bed better, at temp) I haven't needed a raft. I noticed the temp problems others complained about but I saw it with the shipped nozzle too. That's probably the reason many suggest the mosfet upgrade. No fan and it gets up to temp, 25% or more fan and it struggles. I pushed the temp to 220 and it holds at 215 with your nozzle printing PLA.

Because this goes around the outside of the fan you have to loosen the fan so it can fit between the fan and extruder. Probably an obvioious observation, but just throwing it out there.

hey bro when i install it my temps cant reach the 200c and i have the nozzle al the way up.
Can u help me?
Best Regards

I need this fan duct with an air outlet 6mm lower than it is. If I mount this fan duct on my A8 the air is blown directly onto the nozzle. So I cannot reach a higher temperature than 180°C. When my nozzles touches the heat bed the fan duct stands 6mm above the glass. :(

This did not fit my a8. The opening is too big on this piece once printed.

It is different then the original one. Try to dismount the fan and install it

not sure what is going on. tried to print twice. hung up in the same spot. odd. I was not present to see it. Trying one of the extended versions...

Thanks. Easy print and efficient. I can't comment on the quality yet but I can do structural comparisons.

The great thing about this print is that it is very secure and does not need adjusting. It sits higher than the nozzle so prints do not get dragged and ruining.

Circular duct: I find that the duct is heavy and tends to sink/ drop. Also, the level is sits with the nozzle (many overnight print ruined).

Spiral duct: Its a pain to print and the walls are not thick enough. Requires a Gcode setup. Again, the level is sits with the nozzle.

Hope this helps.

I have a lite problem with this fan duct, when im printing a wall object i clearly see that wall side that is not facing fan looks worse, just like PLA wast not cooled enough while printing from that side, what you suggest i should take nozzle higher to relative fan position or lower ?

I have the same question as GeneticCheatah. The acrylic thickness of my sensor mount is 5mm. So I think a 5 mm extension of the part between the mount and the semi circle would do the trick. Could you make me such a version?

Could you design a slightly extended version so it’s still alligned with the nozzel after installing an auto bed level sensor mount? The acrylic thickness of the mount pushes the fan further away by about 2mm and I don’t want it to ruin the affectiveness of the fan duct

Thanks I think it's the best fan duct for the anet A8

Thanks working great, snug fit. Doesn't need any tape or glue

I just sliced this in Simplify3D 3.1.1 and 4.0.0 and it deletes one of the walls as shown here - http://i.imgur.com/Bowg5tk.jpg Must be too thin of a wall or something there.

The reason you give for creating this Thing (circular one falling after some time) is the exact reason I came looking for this one. The other one wasted a two hours' print and 20g of plastic. Thank you very much!

sliced on cura 2.6.1 no stress, this was my second print and two things about it amazed me. 1. those supports that just snap away .. how does it know>? Magic! and suddenly I am able to be in the same room as the printer without industrial strength air protection. THIS is the best upgrade of all the upgrades I have because without it I would probably never print anything due to the pain generated by the standard fan.

Thank you for making and sharing

Fyi... I spent half a day trying to get this to print...For some reason it does not slice properly in Cura 2.6.1.... Went back to Cura 15 and it was perfect.... Never seen this before...

Works great prints in 47 minutes and requires 2.18 meters or 6 grams of filament

A cleaned up mesh would be helpful. It seemed it was sliced up with a lot of strange artifacts within the walls and top. Still, first print alright.!

I think it is so awesome that you have included the blend file for use Blender. That has been my all time favorite program since early 2000s. Thank you.

Wow! This is a really quick print! I started about ten minutes ago and it's halfway done. I am not printing with supports but it seems to be going great so far. Great work!

I'm using its circular cousin, but sadly, as i have a plate for my auto levelling sensor, all the fan ducts are offset from the extruder nozzle...
Would you be kind enough to design one with a 3.8 mm longer "neck" thing?
Thank you.

Hi, can you show me on a picture which part you need longer (use the picture from thingiverse).

I am also really interested in this new design as I have the same problem with this fan duct because of the autolevel sensor plate which is 3mm thick.

Thanks a lot for your answer :)

Here is a picture of the part, highlighted.
It has to be stretched horizontally as if you wanted to make it closer to the extruder nozzle. This will compensate for the sensor plate.

Link to area I believe Loico says needs to be extended to accommodate the "stock" Anet leveling sensor bracket. Area between the yellow lines is what is to be extended. That having been said, I'm using it with that sensor and bracket and it works fine, but this "lost reach" is pushing all of my OCD buttons. ;)


Not sure if the bracket is 3.8mm or 3mm thick, I can measure when I get home, unless someone beats me to it. The bracket installs between the fan and the extruder, so it "pulls" the fan duct towards the front of the printer by the thickness of the mount. This is the sensor and mount in question.


Oh thanks. I only noticed now that Thingiverse ate my link for some reason.
I used a caliper to measure the plate between the fan and the extruder motor. It showed 3.8 precisely. But it may depend fomr one manufacturer to another maybe.

did you find the time to modify the file already? :)

Any news on this topic?

Sorry for the late response, I had ton print it and test it on a couple of prints.
As many said, it blows quite high and lower the extruder's head temperature a bit, but works like a charm with the 3.8mm offset.

Thanks A lot!

How much infill % did you use on this print? Would 25% be ok?

It doesn't do infil on this because it is thin so it doesn't matter.

Comments deleted.

Printed this and tried to use it, ended up cooling my nozzle way too much, to the point that I got a thermal runaway...

Me too. Perhaps the original one is better?

I made this and had the same cooling issue. Temps were very unstable. My extruder tip is screwed out just enough so the stock white fan duct clears the bed while printing. No more, no less. I went back the the stock fan duct.

I have to retract my previous post about what I said above. It turns out the unstable temps were NOT caused by this fan duct. Instead it was due to me not changing the power supply from 240 vdc to 120 vdc. While sorting my new A8 out I measured to output voltage of the power supply. It was measuring less than 9 vdc instead of 12 vdc. Once I flipped the power supply switch from 240 to 120 everything changed. My bed as well as the nozzle now heat up 3x faster. Today the cooling fan duct has no effect on the nozzle temp. I'm just glad I didn't damage anything. I'm surprised my A8 worked at all.

This fan duct seems to be working very well.

well at least you know it works well

even if you bring your fan speed down to 25%

yes me too, it looks like it needs a degree or two of pitch down. Sweet design tho was thinking of taking a heat gun to it see if i can make it work .

Maybe your nozzle / throat / heat block is not mounted properly e.g. it is too low.
It also helps a lot and is highly recommended (no matter what fan duct you use) if you run PID auto tune when you install new fan duct - the temperatures are much stable afterwards.
Anyway, I'm working on a different new fan duct now, so keep an eye :)

Great design, works perfectly :) Thanks

Sorry, 1 question, what distance should be between tip of the noozle and the bottom of the fan duct? I read it is something around 7/8mm ?

I just printed this, but havnt tried it yet.
But it seems to be a little short.

It depends on how you screwed your throat tube if this is what you mean by "short".

I made one... and even when it's near perfectly level with the nozzle tip (added 6mm height for mine, thanks for including blender file!) it blows too directly and cools the head. Fan speed reduced to 75% max 50% min seems to work... but not ideal. Air holes should point slightly more down angled to avoid cooling the head itself so badly.

By far the best fitting and usable fan duct I've found for the Anet A8. I've tried about 4 or 5 other circular designs on here, but they all warped after the first print and one was so big it would hit the left Z rod when it would go to home. You do have to remove the fan to put this on, but it is only two screws and takes like 30 seconds. I printed mine with PLA at 0.2mm layer height with 100% infill.

I've been using the semi circular one... http://www.thingiverse.com/thing:1874390 and it's been holding up fine in PLA, no warping. Just doesn't blow high enough... and this one blows too high :-(

Extruder Cooling Duct for the Anet A8 Printer
by Leo_N

im making a remix of this to my 3d printer (custom). what is the recommended distance between the tip of the nozzle and the bottom of the fan duct?

For my own printer, the fan duct is designed in a such way that the streams of air are focused at the center of the circle, around 7-8 mm below the bottom of the fan duct.

to small height....you can upload other height sizes?

to small height....you can upload other height sizes?

Note: You must remove the front fan and shove (read: rather forcefully) this piece over the airflow opening, then re-mount the fan to the extruder unit. Not a major inconvenience, but something to be aware of.

A tip for improving the model: Make the hollow channel on the side wall go straight through the top, this would have made installation a bit easier.

What is the infill density

I have made several of the circular ones and I made the mistake of adding infill, this is a hollow component so no infill.

Comments deleted.

Great job, are you using Cura and if so would you share your Cura setting? I'm new to 3D printing I just got my Anet A8. Thanks

I've had better luck with Slic3r than Cura, in Repetier, on mine. Cura won't even insert M190/M104 heatup in the G code for me or any temp changes. Only problem I've had is getting bridging to work right but I'm thinking it's cooling/fan related more than settings... 30mm/s with a 0.5 bridge flow ratio is what I'm using now with the full circular duct... hoping this duct fixes it so I can go back to 1 bridge flow ratio. Did you get the 0.4 nozzle version? I replaced the nozzle mine came with as well, using a .3 right now and the quality is insanely better.

How did you manage to print the top flat surface that comes right out of the semi-circular one without any supports?

Bridging :) Most 3D printers are capable of bridging at least an inch. I find I can bridge around 2 inches before I really need supports.

Comments deleted.

Great design! Thanks

You read my mind. I print the full circle fan duck but the air flow is not enough.