Taz4 / RAMBo aux fan wiring?


Here’s my issue:
Stock Taz 4 w/ fan
edit: stock Lulzbot PLA slic3r medium speed settings
PLA jams during hours-long print EVERY TIME.

The “cold” upper bit of the hot end is brand-your-skin hot.
Extruder motor pretty hot.
Hobbed bolt is relatively cool.
Worse with cheap PLA, better with quality PLA, but ALWAYS.
PLA is wedged in hot end and difficult to extract.

My goal:
To install an auxiliary fan, dedicated to keeping the heat sink sunk.
I don’t need to control it with Slic3r - if I have to, I’ll just put a switch on it or have it always be on.
:bulb: Bonus points for independent software control.

Where should I tap into power on the RAMBo board for a second independent fan?
For the time being, I am just going quick and dirty with a 12V wall wart.
(Please don’t tell me to print faster - I want the quality of a slower print. That is a kludge; I want a solution.)

Editorial / background:
I have given up on the possibility of printing ABS with the Taz 4.
The hot bed is useless for maintaining a warm printing envelope.
ABS is completely unprintable on this machine without horrid curling/ warping.
Even in a box. Even with a fox. PET is garbage,
My metric is a $700 printrbot kit that has consistently kicks my Taz’ butt when printing ABS.
I have high but reasonable standards for print quality, as I print my designs and sell them to paying customers.


Did you ever find a way to wire this directly to the RAMBO?, I am looking at the 5V Aux out Port (next tot he MOSFET outs for the extruder/hot end), and thinking about a 5V fan.

I haven’t, and it has caused me a little grief. I have labels pasted up in random and strategic places reminding me to turn on the fan, but I still occasionally forget and occasionally I get a PITA jam in the hotend. I’m getting better at remembering, but the potential always exists that I will forget and ruin a long print. Do 5V fans even exist?

Assuming you are using Marlin-2014Q3 firmware

Plug the extruder cooling fan into the 2nd fan port on the Rambo (EX_FAN1).

Open up Configuration_adv.h

Scroll down to the // Extruder Fan Setup section.

Change #define EXTRUDER_FAN_SETUP from 3 to 4 so it says:


You want to end up with this:

// Extruder Fan Setup 
// If set to -1 all Extruder fans will be disabled
// If set to  1 only EX_FAN_0 will be used as a nozzle cooling fan for Extruder0
// If set to  2 EX_FAN_0 and EX_FAN_1 will be used as nozzle cooling fan and will switch between active nozzles
// If set to  3 EX_FAN_0 will be Controlled by M106 S255 and EX_FAN_1 will be controlled by M106 P1 S255
// If set to  4 EX_FAN_0 will be used as a nozzle cooling fan and EX_FAN_1 will be used as a heat sink fan
#define EX_FAN_0 FAN_PIN
#define EX_FAN_1 FAN1_PIN

    // Extruder cooling fans
    // Configure fan pin outputs to automatically turn on/off when the associated
    // extruder temperature is above/below EXTRUDER_AUTO_FAN_TEMPERATURE.
    // Multiple extruders can be assigned to the same pin in which case 
    // the fan will turn on when any selected extruder is above the threshold.
    #define EXTRUDER_0_AUTO_FAN_PIN   EX_FAN_1
    #define EXTRUDER_1_AUTO_FAN_PIN   EX_FAN_1
    #define EXTRUDER_2_AUTO_FAN_PIN   -1
    #define EXTRUDER_AUTO_FAN_SPEED   255  // == full speed

This line


will make the fan automatically come on when the hot end reaches 50 deg C.

After making the changes, you will need to ref-flash the firmware.



This is AWESOME. Thank you!

This is AWESOME. Thank you!

Pretty much guaranteed that with the auxiliary fan hooked up as described and the firmware modified and re-flashed, you will no longer have a clog due to heat creep.

The mod keeps the fan on whenever the extruder is hot. Unlike the other method of using a single, dual port fan duct, that only blows air while printing, and even then, only at a fan speed that the slicer determines is appropriate.

And if you have wrapped the nozzle threads, covering the part that goes through the heater block as well as the nozzle, you will also eliminate PLA leaking.


Thanks for all the help guys,

here is a link to the connector for that fan port:

(link credit goes to this previous thread https://forum.lulzbot.com/t/taz-fan-mount/298/1)

I am excited, thanks!

So should this be a 12 V fan, or a 24 V when used with EX_FAN 1 ??

If you are using a TAZ 4, you’ll want a 24 volt fan. Don’t know what voltages previous models used.

As for that connector, likewise, on a TAZ 4, the 2nd fan will already be wired (with that connector) to the 2nd extruder wiring harness connector on the case. So…If you don’t want or don’t have a need, to make a wiring harness for the 2nd extruder, you can just push a couple of wires into the appropriate pins of the 2nd extruder connector (1 ground and 1 fan hot lead). It would be best to tin the leads first so that they are nice and solid and thick enough to stay in the holes.

Please be careful not to short any wires :astonished:

Extruder Harness.jpg

Just so there is no confusion.

In order to get automatic cooling of the Budda Heat fins with an auxiliary fan mounted on the left side (facing the extruder), you’ll be making the firmware change as noted previously, and hooking the fan up to the Extruder 1 (2nd extruder) fan port on the Rambo. This is the 4th plug in from the left, or the 2nd plug in from the 15A fuse. It is called FAN 1. Don’t confuse this with FAN 2, which is already wired to the case fan.

On a TAZ 4, this Fan 1 connection is already wired to the 2nd Extruder Wiring Harness (which is missing unless you make your own harness). The Fan is connected to pins 9 and 10 of the connector.


So I just implemented this. It turned out great. Just a heads up for some people though. The wiring diagram in this thread (from Lulzbot) doesnt have the right connector for the exturder fan in the picture. The one I linked in this thread earlier is the correct connector.

Also, Once I got it all set up and flashed the firmware with the fan setup change: The new aux fan was at FULL SPEED, which was super overkill and very loud. full speed is 255, I turned it down to 100, which is much quieter, I might turn it down further.

Thanks for all the advice everyone, I should never have to worry about heat creep again.

Can someone tell me the name of the wire connector used for the fan? Or send me a link to buy them?


This is the correct connector for the EX FAN 1 slot


That looks nothing like what is on my Taz 4

Ok, so that goes into the Rambo, i need the connector on the other end that plugs into the fan. I actually need the same end that is on the fan that plugs into the wire harness

This is the connector that I need
Fan Connector.PNG

I cant find this one. I would email lulzbot support and ask them for the part #, they will get you it.

Here you go:

from: http://devel.lulzbot.com/TAZ/accessories/extrusion_fan/12_and_24_fan_bom.ods

so do you actually have to use this http://www.newark.com/te-connectivity-buchanan/796634-2/terminal-block-pluggable-2pos-30/dp/34C9465?in_merch=true&MER=ALT_N_L5_TerminalBlocks_None to make this work?

or can you just solder directly to the board if you dont care if it runs 100% of the time?