Hey! This thing is still a Work in Progress. Files, instructions, and other stuff might change!

Rear active cooling duct with 40mm fan and LED lighting (Duplicator 4 dual)

by CyberMosfet, published

Rear active cooling duct with 40mm fan and LED lighting (Duplicator 4 dual) by CyberMosfet Dec 5, 2014
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This is another fan duct for the duplicator 4 dual to provide active cooling and LED light to the nozzle working areas. The 40mm x 40mm x 10mm fan is positioned vertically behind the stepper motors. The big advantage of this is that the fan does not obstruct the view of the nozzles. I printed it out with clear PETG filament so that the whole thing lights up with the 2 installed LEDs.

Most of these type of cooling ducts require active cooling to be build, which is a problem, since you don't have an active cooling duct yet... This model includes fine bridge support structures already included in the design. This can be removed once the print is complete. These structures offer more effective overhang support then the support offered by most slicing algorithms. This makes it possible to print this item without active cooling.

• Clear view of the nozzles - the fan duct is at the back.
• The LEDs illuminate the nozzle working areas.
• Less obstructions within the fan ducts = more air flow.
• Air is concentrated on the nozzle tip, not the heating element.
• The nozzle heating elements are not obstructed = no heat build up (no melting carriage - hopefully!)
• Clears the heat bed tray at the back (it just-just does in my printer!)
• Easier to print then others. (If you download the file that has the necessary support included - don't use your splicer's support.)
• Attaches to the rear carriage with two 3mm bolts and nuts.

Changes made (9 Dec 2014):

  1. Back wall thickness increased from 1.1mm to 1.2mm.
  2. Extended centre wall to support the middle protrusion of the duct when it prints - it curled upward while printing.
  3. Fan set 1mm inward - the 10mm fan stuck out by 1mm.
  4. Changes to the temporary support of the blower outlet ridge - it curled upward while printing.


There are 4 files that can be downloaded. One set is with LED holes and one set is without LED holes. Then there is the option of downloading it with or without included overhang support structures.

I suggest you print the one with the included support (Support_included_duct*.stl) which will make things much easier to print. It has fine support pillars on the correct places that can be easily removed afterwards using a stanley blade and a small ruler. (see attached images)

I printed it out using the following settings:
• 0.2mm Layer height
• No Support (support included in the design)
• 3 shells with 100% infill
• Not faster than 50mm/second feedrate
• Clear PETG or ABS filament (High melting point filament)

You need to print out 2 fastening clips. You can get the fastening clips from http://www.thingiverse.com/thing:537918 called ActiveDuctV2.0_Clip.stl. Use two 3mm bolts and nuts to fasten the fan to the carriage.

The 40mm fan is fastened with two 3mm self tapper screws. The tollerance of some of these fans are extreme - some fans will be a tight fit. Be carefull that you don't break the back wall of the duct when installing the fan. The fan power can be controlled directly with the MightyBoard of your duplicator - from where you can control it via the GCODE. Please visit http://www.thingiverse.com/thing:537918 to find out how to connect the fan to your duplicator.

In the pictures I used red LEDs to illustrate where they are located, but eventually I used 5mm white LEDS (20,000mcd 3.2V 20deg). Connect the two LED's in series. Connect them up to the 24V PSU through a 1K5 1/4Watt resistor. This drives the LEDs at about 12mA. Don't drive the LEDs too high. Together with the high temperatures this can shorten the lifetime significantly. Solder the LEDs and wire harnass together. (if you can't solder then rather get someone that can - remember, plastic melts, use a fine soldering iron - else it would look like King Kong spit on it...)

I also included the Design Spark Mechanical .rsdoc file if you want to take it from here.

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I printed one useing MakerWare with the no support file in ABS without any probs works good. But would like to change nossle so would wrap around like thruit00's active cooling fan duct v2, his front mount is around 1/2" from working on back. But have had no luck trying to combine the two, if someone could do that it would be great!

Hi having problems with the supports, what size head did you use? Maybe my 0.4 is too big??

Sep 1, 2016 - Modified Sep 1, 2016

I'm using this Fanduct on my CTC Printer for around 5 Months now.. And I'm really happy with it!

There are a few Problems though:

  • 1
    Since it is on the back, keep in mind it might collide with your stuff.
    I'm not sure if it did that right away, or after i added the Filamentholder (thing 918137)
    It WILL collide if you decide to add a bearing to the top of the Z-Axis, you shouold remove the bearing rightaway, it only makes the Axis worse.
    If you added a buildplate with some kind of clamps, you might need to look out for that too, since this is hanging rather low. But this applies to all fanducts i know.

  • 2
    I printed mine in PLA and it seems to have melted out a bit, print it in ABS or another Plastic.
Nov 15, 2015 - Modified Dec 15, 2015

Given up on this. I will need to rethink the whole rear cooling solution. My printer doesn't allow for much space at the back so probably need to custom build something half as thick as this, tricky.

Did anyone ever figure out why all the slicers will not generate a file with the built in support? I've tried all ways and nothing works.

I modified the supports in my 3D software and made them thicker... job done.

What software did you use to make this freakin'amazing work?

What software did you use to make this freakin'amazing work?

I had the same issue with supports not printing at all despite using the file that has supports in the preview although I still ended up with a usable print anyway. Also, in case anyone has tried to install this on a Flashforge Creator Pro and had the same issue I did with the clip being too small I created a new clip that worked for me, it is located at http://www.thingiverse.com/thing:788204.

Clip for rear cooling duct for Flashforge Creator Pro

This clip worked (not perfectly) on FlashForge Replicator Dual as well. Thanks.

Apr 12, 2015 - Modified Apr 12, 2015

Nope supports didn't print even though they showed in the preview. Used the with supports file as well.

Has anyone printed this successfully with Slic3r? I'm using the supports included file but I can't get the lower column supports to print. Only the very back row (slightly larger ones) will print. The fan opening supports print just fine so I'm not sure what is going on.

Feb 2, 2015 - Modified Feb 17, 2015

I've printed the ducting successfully (using Simplify3d) and it fits perfectly (great design) but I seems to be missing the two little clips that are held on by the screws. Or am I missing something?

I drew up a simple clip and printed 2 of them and they hold the duct in place nicely and the fan works well :)


or search "clip for fan" if you want to print your own.

Clip for Fan

How did you print this with S3D? I'm having the same issue the guy below said. The support's don't show up in the build preview with built-in support file.

can this be used with http://www.thingiverse.com/thing:537918 providing a multi-fan cooling setup?

Active Cooling Fan Duct v2 for Replicator 1 / Duplicator 4 / FlashForge / CTC

I will answer my own question. Yes it will fit with the other fan duct on the front.

So my first printed one I had been using warped and started dragging on the printed piece. :(
I printed it with one shell which then left two very thing walls and no in-fill as the gap is two small for it (when using defaults).

So, I have tried printing another one, this time with Simplify3D and it's not loving your model. :(
Your internal supports don't want to be printed. It shows the outline of them at their base but no height to them. The same with the tall verticals which help the fan top stay up.

If I download your non-supports option and try get S3D to add supports it does not seem to think anything on the left needs supports. Only the right gets them.

Quite confused....

Could you perhaps re-export the support files and email them to me? Or email me your 3gx file?

Happy new year!

I am having a whale of a time trying to print this. :(
It is really struggling to do the overhang when it starts covering up the bottom ducts.
Towards the rear, 10mm or so from the LED, as it curves in towards the front, could you put a small pillar there so it has something to hold on to?
The flat cover is ok, it's not struggling with the straight span, just the curved part at the back, the edges keep curling up.

I am using a HPB, 100C and 230 on the extruder with clear ABS.


Crispin, thanks for trying this out and thank you for your feedback on this.
Did you print the "Support_included_duct_5mm_LEDs.stl" file? This file includes temporary support pillars under the whole overhang including at the back where it curves toward the front. You can remove this support after the print with a ruler. This would really solve the curling-up problem - and allow for the least amount of restrictions within the ducts.

I really hope you succeed. Please let me know what file you were printing and if the "support_included" file solves the problem.

I made changes on Tuesday on this (9 Dec 2014 - read about the changes in thing info). Please make sure you have the latest .STL file.

I was using the one with supports and they are visible in the rear fan area. Oddly though, I was mucking about with your model in Sketchup and saw the internal supports inside the ducts. I am not sure why it was not trying to print them.

I am using ReplicatorG as a slicer and told it not to use supports. Your model has "supports" but those are rather just short pillars rather than "supports" in the real sense. Or am I confused? (I'm still a noob)

Nonetheless I'll download it again and print it from scratch ti see how it goes....

Dec 12, 2014 - Modified Dec 12, 2014
CyberMosfet - in reply to Crispin

Yes, those short pillars are the supports and they would solve the curling problem - but its strange that ReplicatorG wouldn't print them.

If you use a duplicator 4, you should upgrade your firmware to the most recent (Sailfish 7.7) and then use the appropriate ReplicatorG 40r28 with that (or even better: Makerbot Desktop or Makerbot's Makerware). I am using Sailfish firmware on my machine, Makerbot Desktop as a slicer with Proftweak to fine adjust everything. The firmware update really makes your duplicator 4 a better machine - It takes some effort to upgrade it, but I would recommend it. Follow this link on instructions to upgrade the firmware:
(Jetguy posted a list of instructions on 18 Mar 2014 - if you follow them to the letter you will have no problems installing the firmware)

I'll download the latest version of ReplicatorG and try that. I am already running Sailfish 7.7 but upgrading it was a nightmare - it kept bricking the mobo. I ended up using an ISP to upgrade it directly and that worked without a problem. All is well now.

I like maker bot as a slicer but it does not turn the fan on - does it work with yours?

ok cool, will try print it all again tonight and see how it goes.

Makerbot does control the extra fan. If you install the PSMN7R0-30YL transistor the fan gets controlled by the gcode, or alternatively you can switch it on through the menus. (Just as Thomas explained in "http://www.thingiverse.com/thing:537918")

What I like about Makerbot Desktop is that you can preview the build layers before you export it. Also, Makerbot has these *.JSON profiles where you can fine tune the splicer - you can use a text editor to modify them, or through Proftweak which provides a GUI to these settings.

Here are some helpful links:
and the explanation of all the Makerbot slicer options can be found in this PDF file:

Hope this helps.

Active Cooling Fan Duct v2 for Replicator 1 / Duplicator 4 / FlashForge / CTC

Thanks, Will give those a read.

I have the fan working, oddly my board came with the mosfet installed so it works fine. There was no terminal on it though so had to do that but that's quick and easy...

Successfully printed one - will write a comment about it in separate thread.

Comments deleted.

Very cool. I would like to try this. Could you post a picture of it from the front as if I were looking though the door?
I am using the other one which works well but obscures the nozzles too much. If there is a blob of something I can't get to the print to get rid of it.

Also, is there any back pressure? On the current one the fan is mostly fighting itself and can't move the air through the ducts.

Haha, sometimes I also jump in with my tweezers to remove something... my problem is the small insects that get attracted by the blue LED strip inside the machine only to get molded in plastic.

I have designed the top fan box larger to decrease the back pressure - the first one I made had a smaller fan box (for the air to collect in) and had a bit of back pressure. Also, there are less obstructions in the duct. When I had channels in my first one, the air seemed to be more directional, but much less. I posted more pictures of how it looks from the front - with LED's on and off.