Dual Extruder V2 Heat Block Fan Upgrade

Like many here, I was having significant difficulty in getting reliable prints in PLA, due to filament jamming caused by heat creep. After much consultation with others on this forum, and lots of experimentation on my own, I have concluded that the stock miniature blowers are just not adequate. The following upgrade appears to have completely solved my PLA heat creep issue.

I located a 20mm 5V fan that has nearly three times the airflow of the stock blower:


I designed a shroud to concentrate the airflow on the heat block. I also designed a mounting clip, making it reversible to allow some flexibility in the mounting location. I printed both of these parts in ABS, and here’s what they look like, along with the fan:

The holes in face of the shroud are sized to be tapped for 2-56 screws.

I added a layer of copper foil on the surface nearest the heater block, just for good measure:

Here’s how I have them installed on my Dual Head V2:

I replaced one of the extruder bolts, the one underneath the stepper motor, using an M4 x 35mm machine screw with a 7mm hex head. This also solves the annoying problem of trying to hold the extruder mounting nut in place during reassembly. Underneath the fan mounting clip is a 6mm tall spacer with a 4mm clearance hole. The screw comes down through the spacer, through the clip, and another nut goes on the end to hold it all together and hold the extruder down. I printed the clip at 100% infill so that it could withstand the force needed for that task.

I had originally intended to place the fans both on the same side of the head, which is why I made the clip reversible. However, I found that it works better for me as shown, with the fans diagonally opposed, mainly because in these locations the shrouds don’t interfere with the thermistor wires. In light of this, the clip could be re-designed to make it non-reversible, and extended to eliminate the need for the through-hole spacer. I may get to that…

Everything just barely fits, with very little room to spare! I have not tried, but I believe this design may also work on the single head.

There is about a 2mm gap between the bottom of the shroud (copper foil side) and the top of the heater block. There is no sign of the shrouds melting or discoloring as of yet, after many hours of printing PLA at 205C with a 60C bed. I still need to do a “torture test”, setting the nozzles to 240C and the bed to 110C and lowering the head down to the bed and just letting it sit. Hopefully the shrouds will withstand this.

Here’s the whole thing put back together:

I have attached STL files for both parts.
Clip 2016-04-19 01.stl (25.3 KB)
Shroud 2016-04-19 01.stl (80.4 KB)

That looks great. Definitely a mod to help with PLA.

I have changed the design of the fan mounting clip slightly. I extended one side of it downwards, eliminating the need for the 4mm through-hole spacer. I also beefed it up just a little bit by increasing the diameter around the 4mm extruder mounting screw.

This clip will now only work on one side of the fan, so on the dual extruder it will require that the two fans be mounted diagonally opposite (as shown in my photos).

I believe this clip will also work on single extruder heads, but I have not yet verified this.

STL file attached. Comments and questions are welcome.
Clip 2016-05-05 01.stl (23.8 KB)

(Forgive a maybe silly question please) How do you wire up the 2 new fans?

Each fan in parallel with the existing fan for that head? or in serial?
Or unplug the existing fans and use these instead?

I’ve been using ABS with my Dual Extruder with good results, but I am ready to try some PLA, and this looks like a very good mod.


Remove the existing micro blowers. If you use the fans I recommended, they are 5 volt fans. You can clip the wires from the existing blowers, and then splice the new wires onto them. I am certain the wires from the existing blowers end up in parallel before they get back up to the connector. Just be sure you don’t accidentally connect them to the supply wires for the 40mm print cooling fans, those are wired for 24V, and they are switched on and off via the controller. The 5 volts for the extruder micro blowers is always on when the printer is powered up.

I’m glad I did research here before I tried to design something myself. You just saved me a ton on time. Thanks a lot!

Did you end up doing the “torture test”?

I printed out the parts and just I started to assemble the mod. I can’t help shake the feeling it will melt with I print ABS + HIPS.

Update: my print from Cura 21 was very thin and weak. Ultimately it failed. I also attempted a “high detail” print and it was the first failed print I’ve ever had on the TAZ6. I tried Simplify3D and it sliced STL with unwanted gaps along the sides. Would you share your cad files, print settings or the gcode? Thanks

I never got around to the torture test. I’m so happy with PLA and the occasional PVA support that I don’t even print in ABS anymore, sorry. And unfortunately I did not save the configuration files from when I printed the shroud and the clip. I generally would print ABS at 240 with a 110 bed, though. I don’t recall what layer thicknesses I was using or anything like that. Sorry.

Well I did the upgrade, but I still get horrible heat creep on the back nozzle. It’s pretty frustrating, But at least it was worth a shot.

Well that is a drag, and kinda surprising. It cured my heat creep problem 100%, and I use the back nozzle for virtually all of my printing.

Do you have the little fans oriented so that the air blows in against the heatsink?

What brand of filament are you using, and what temperature are you printing at?

I use Verbatim PLA, and print at 205, with the bed at 60.

Also, what print speed do you use? I use 40mm per second. I have no idea what these things are capable of, but that works, so I just leave it alone.

Yup I have the fans pointed directly at the fins (at least when I put it together originally. I figured I would take the unit apart tonight once I get off of work and see if something shifted or anything. I’m using Orb Polymer Blue Jay PLA and Push Plastics Gold PLA. Orb at 205(Back nozzle), Push at 200(Front nozzle) bed 60, Speed is 50 mmps .

Knowing my luck, the back vent cracked, came loose or something else dumb that I’ll look at it and go “duh” lol.

Thanks for responding to the post. I know posting on such a big forum we can get lost in the crowd sometimes.

No worries. I was pulling my hair out a year ago trying to fix the heat creep problem with PLA, so I can certainly understand the frustration. I will try to check consistently.

I think even if the rear shroud is cracked or compromised, it should still be much better than stock.

Something else just occurred to me also. Before I came up with the heatsink shroud design, I did a modification to the actual extruder body, putting the same 5 volt micro fan on it, and directing air through channels adjacent to the filament and out of the bottom (details here: https://forum.lulzbot.com/t/pla-heat-creep-solved/3236/1 )

That approach was only partially successful, but when I installed the current fix, i did not remove the fan from the rear extruder body

So, my rear extruder also has a fan running in the body of it (I never installed it on the front one). Is the current shroud and fan fix working for PLA on your front extruder, but not the rear? I wonder if I am still getting some benefit from that extruder body fan. I have done 99% of my printing on that extruder. The few jobs that I did use PLA in the front extruder (without the body fan) did work, though.

Here’s pictures of the shroud I made.

So I looked at my head tonight and everything looks fine. But I decided I would take pictures of it and post them. Maybe you’ll see an issue I didn’t notice. Before I found your post I did design a fan shroud that would use the cooling fans but I wasn’t successful with it. maybe the combination of the two mods will work together… I’m posting pictures of the fan mod as well.

Well, it looks good to me. If both fans are working it “should” probably be doing the job.

Are you completely sure that it’s heat creep? I ask because if the nozzle is too close to the bed it can generate back pressure and cause the hobbed bolt to dig into the filament. For me, this has been more of a problem on softer filaments like PVA, but I wouldn’t rule it out for PLA.

I use a double-folded piece of paper to set the head height. These dual heads are a pain to keep aligned, since the X bars are undersized and the front head is cantilevered so far out.

By the way that dual-function shroud you made is an interesting idea, sorry it didn’t work out. Maybe just as well, as the print cooling fans aren’t necessarily on all of the time, unless you tell them to be. But then that might have adverse effects on the actual print. I like the concept of individual, focused fans on the heat sinks themselves.

I’ll keep checking back, this system works great for me, we “should” be able to make it work for you.

I’m pretty sure the nozzle isn’t too close but it won’t hurt to double check. I have noticed it sags in the front pretty badly due to the sheer weight of the head. I think i may print out the “cooled extruder body”. it wouldn’t hurt to have a little extra cooling. I want to eventually upgrade to the 12mm bars that the Taz 6 has to help with the sag. I’ll keep tweaking away, and I’ll keep everyone here up to date. Who knows, maybe we can make this a standard upgrade and make it easier for everyone to use the Dually. I look forward to that day.

I keep coming back to this. When I realized that the cooled extruder body helped, but did not totally cure the heat creep problem for me, and I did the heatsink fans and shrouds, I put a switch on the existing extruder body fan that I had (on the rear extruder body only). At first I ran the prints with this fan off, and in many hours of printing with PLA I had ONE failure. But as I’m sure you know, just one heat creep failure on a big print job can ruin your whole day, so from that point on I just left the extruder body fan on, and I’ve had zero failures since.

As I said though, I do 95% of my PLA printing with just the rear head, so we don’t have conclusive data yet. Maybe we need both. The successful prints that I did get from the front extruder (sans extruder body fan) might have been pure luck.

Have you seen the open rail upgrade that’s available on these forums? I think the user that has spearheaded that is Piercet. It looks significantly stiffer than even the 12.7mm rods, and uses off-the-shelf components.

Yup, thats one of my projects, the core bits are here:

X http://www.thingiverse.com/thing:866604
Y http://www.thingiverse.com/thing:949082
Z http://www.thingiverse.com/thing:1038673
The Anti wobble (optional) http://www.thingiverse.com/thing:1089626

The X and The Y axis mod offer the biggest bang for the buck. I attached two dual head setups to an X rail to see if it would deflect once. It did not.

Ok… weird thing… I took apart the head and replaced the bolts holding the fans to longer ones because I didn’t like the shorter ones, put it back together and try a test print.

It seems like now the mod is working great… I was able to print 2 3D benchys(the boat) and a Dual color Pikachu… I’ll keep updating on here… but it seems like it’s working great. I’m working on getting it tuned in just right so I can print without a ooze shield or wipe tower. But here’s the benchy I did.

Here’s the current settings I used.
Layer height: .25
Shell: 1
Fill: 20
Print speed: 50mm/s
Nozzle 1 temp: 200
Nozzle 2 temp: 200
Bed: 40
Wipe Tower: On
Retraction: 1
Gold PLA: Push Plastics
Blue PLA: Orb Polymer

This alone makes it worth doing. The biggest pain of the dual head is keeping the front to back alignment true, it is nearly impossible with the stock setup.

Thanks so much for your efforts on this.