Taz5 Hexagon HE:Control of 5v fan???

Hello, I am a modeler /3d printer, also an animator/ code enthusiast with some engineering background(associate degree).

I purchased the Taz 5 for $2199.00 in April, 2015.
I now build my own. I have redesigned almost every piece of the Javelin works. I cannot afford 5 hundred dollars right now. Thank you Jebba for keeping the designs available for reference you have my respect :mrgreen:

All redesigned parts are printed and all electrical leads terminated.

Have been searching the latest version of firmware to find where to control the two heatsink micro fans of my dual extruder.

I cannot find a PID solution or a bang bang solution :bulb:

But, where in the firmware do you control these pins(PWM fan/5v aux)??? config.h, config.h adv., pins? :blush:

The problem is not how to control fans 0 and 1 with the m106 s255 and m107 commands. I want to control the 5v micro fans.This fan needs to slow down about 23% it is cooling my hotend too much. This will reduce the life of a couple components.

Thanks Grem

You’re talking about the hotend heatsink fan? Its supposed to always on… otherwise the heat will creep up from the heater and melt your filament in the hotend.

If its cooling your hotend too much, you’ve got a design flaw.

Not being able to control the fan is the design flaw. :laughing: Giving less power to the fan was the objective.#less rpms is not an enormous thing to ask for.

I guess these fans are uncontrollable THROUGH the RAMBo board pins they are assigned? Right. :neutral_face:
micro 5v fan (a front facing fan) too powerful? :question: :ugeek:

Not having some way to control a vital part of a the extruder’s design is a major design flaw? :question:

1.My question was: how do you control these pins that power the 2 micro 5v fans for both extruder heat sinks (aux 5v out and the PWM fan out) in Marlin???

Umm… okay. If you turn off the heatsink fan, I guarantee you will need a new hotend from the filament melting in the chamber.

ENGINEERS design things for a reason. A heatsink to dissipate heat. A fan to assist because the heatsink alone can’t keep the chamber cool.

Here’s a thought, unplug the fan and run your hotend… Please post the results.

It is a common power supply(5V) on the RAMBo that is used by the control logic also. No, you can not mess with it and expect the printer to function.

I think if you have a change/fix that will fix it they might incorporate it into the final released design if it follows open source guidelines. But I think right now as it is still being worked on. ???

Designing a fix is your best shot right now along with coming up with extrusion cooling for the prints. :ugeek:

If I remember right the original dual had no cooling also.

Hello, Mr Chen,
I never said turn off the fan I said dial it back couple of percent so the thermistor is not fighting the fan. And, what is wrong with turning off the fan when there is no load on the hotnend to begin with.

Just turn it off when the hotnend is not hot and turn it on in increments as needed by some closed loop solution. Your reply did not help at all. And you are a bit rude.

Hello, Mr Manley, thank you for addressing my question in a logical way. This shows maturity and a good nature.

Information on control of the micro fans seem to be non existent on this forum.
This question should be fundamental. There is only one type of 5v fan and where it is controlled should also be fundamental and accessible on a $2200.00 machine. $190.00 8 bit processor should have voltage control over it’s core components.What is this 1977.
This is a rip off. I will go with the azteeg next time.

I am learning a lot from trying to source parts for this open hardware. It has been bought up in the United States.That is why it is open. Try finding a stepper motor in the United States (not China) that matches Lulzbot’s specs, Try finding 34 mm body stepper with 1.5 amp and vac of 2+volts that has enough holding torque to do the job. 40 NCM IS suggested. around 20 something has been the norm.

In marlin(config.h_adv.) this fan is refferred to as nozzle cooling fan, I can find no reference to heatsink fan, although I know this is how lulz and some reprap forums describe this fan. I will not fight about this, it is counterproductive and would express an ulterior motive.

I have traced the 5v micro fan on the first extruder to the PWM header to the last set of pins 1234(56). The schematic from Reprapdiscount and Ultimachine reads as pin4.So we know these 5v fans are not controlled by any of the code in config.h_adv.

I was combing through a lot of lines of code and came across some interesting code we know for sure is in the configuration.h file!

Increase the FAN pwm frequency. Removes the PWM noise but increases heating in the FET/Arduino
#define FAST_PWM_FAN

// Temperature status leds that display the hotend and bet temperature.
// If alle hotends and bed temperature and temperature setpoint are < 54C then the BLUE led is on.
// Otherwise the RED led is on. There is 1C hysteresis.
//#define TEMP_STAT_LEDS

// Use software PWM to drive the fan, as for the heaters. This uses a very low frequency
// which is not ass annoying as with the hardware PWM. On the other hand, if this frequency
// is too low, you should also increment SOFT_PWM_SCALE.
//#define FAN_SOFT_PWM

// Incrementing this by 1 will double the software PWM frequency,
// affecting heaters, and the fan if FAN_SOFT_PWM is enabled.
// However, control resolution will be halved for each increment;
// at zero value, there are 128 effective control positions.
#define SOFT_PWM_SCALE 0

any constructive thoughts??

On the lcd screen it reads 1 percent for fan usage.
This means there is a parameter somewhere that allows this one percent to happen,Logical right?

How do you alter this parameter if the fan is on a PWModulation fan header putting out 5 volts. This should be controllable.On/off at least.
Thanks for your time,

Hello, Another Question,
If there is no software solution at this time, Would adding the right resistor inline with the lead be a fix, :open_mouth: or would this hurt the board in some way. :astonished:
:bulb: The energy would be used and the fan slowed relative to the frequency of the resistor.
Thanks Grem

The 5 volts is to run any logic you add to the PWM output/analog input pins like additional control chips, and such. All the 5 volts on the RAMBo is supplied by a simple 5 volt regulator circuit located in the upper right side of the schematic. It is available on a number of different pins on the board connectors, but is not controllable software wise.

There are plenty of ways to reduce power to the 5V blower fan, or even place it under software control. However, if higher temperatures are desired, increased heater power would be a more logical approach. Keep in mind that hotends are specifically designed to provide a sharp transition from cold to hot. In engineering terms, infinite heat sinking would be ideal (infinite stream of air across the cooling fins). In fact, water cooled hotends are not uncommon.

Now, if you are determined to try this, there are a lot of ways to reduce 5V blower fan power.

Simplest is a resistor. Measure the current draw, determine the effective running resistance of the motor, and chose a resistor of comparable value. However, a dumb resistor will not allow the fan to draw extra current at startup, possibly leading to random, unpredictable, failure.

Next simplest would be an LM317, three terminal adjustable voltage regulator. While this is better than a resistor, low voltage settings may not allow sufficient voltage for reliable startup.

Software control from the RAMBO board is also possible. Usually, there is a case fan which runs whenever the stepper motor drives are engaged. For times when the hotend is active, but stepper motors are not, the “M42” G-Code can be issued. Cautiously, an LM7805 linear regulator could be used to share the 12V case fan power with the 5V hotend blower fan. However, if for any reason the case fan is switched off while the hotend is still hot, catastrophic damage would result.

Finally, the best solution, and what any real hacker, maker, or engineer would immediately contemplate, is a dedicated fan controller. An Arduino and darlington or MOSFET transistor would be sufficient. Hotend thermistor voltage could be monitored, or a separate thermistor could be used at the hotend cooling fins. Any reading outside room-temperature would then trigger a fan startup and PID control sequence.

Ultimately though, all of these techniques for fan control are more complex, and therefore less reliable, than simply leaving the hotend cooling fan running continiously at all times. Further, any drop in cooling fan performance will correspond to an increased risk of severe jamming. Turning off such quiet, low-power fans should be of negligible concern compared with having a printer that works reliably. Other members of the community have been exactly right trying to explain that no control system for the hotend cooling fan is warranted.

More to the point, more details regarding the ACTUAL problem you want to solve (fan noise, insufficient hotend temperatures, noisy thermistor readings, etc) would be helpful. If you have to ask whether a series resistor would be able to reduce fan speed, you probably don’t have the expertise/methodology to know what the right solution is, let alone tinker with reducing hotend fan performance.

By the way, does anyone else see parallels with posts from “chriscalandro” about software fan control for the dual extruder? Perhaps these are related in some way…

Information on control of the micro fans seem to be non existent on this forum.
This question should be fundamental. There is only one type of 5v fan and where it is controlled should also be fundamental and accessible on a $2200.00 machine. $190.00 8 bit processor should have voltage control over it’s core components.What is this 1977.
This is a rip off. I will go with the azteeg next time.

You ask questions and yet do not understand the reasoning for the answers? The heatsink fan is on 100% for a reason… to reduce the chances of heat creep causing a jam. Anytime the hot end has filament and is on, the fan needs to be also on. If your capable just use your Azteeg controller. If you just want to control the speed to say 50% all the time, it was suggested you add a resistor. Pretty basic. A lot simpler than changing over a 3D printer control system.

Added Your statement: The energy would be used and the fan slowed relative to the frequency of the resistor.
Thanks Grem

Resistors (in this circuit) in series with the 5 V to the fan do not change frequency.

Hello Mr. Gremlin.

I’m pointng out that the sole function of the heatsink fan. The printer is not designed to run without it. You’re going to cause yourself more headache than its worth.

All the posts on this forum in the past 8 months, this could be the most detrimental for people that may not know what they are doing and stumble upon your hack.


I understand what you are asking to accomplish but note that everybody else is trying to get more air to that part of the hotend not less and there is a reason for that. That little fan does not put out enough when using PLA but it works fine for ABS. As has already beed said 1. You don’t need to ever slow it down 2. It’s hooked directly to +5v not a control pin.

You say it’s a flaw but it’s designed to prevent you from ruining your hotend and even possibly burning down your printer (or much worse your house). Not a flaw, but go ahead and do what you want just don’t blame Lulzbot for the outcome.

I’ve given this thread a little more thought… Slowing down or stopping the heatsink fan can be positive if the goal is to increase the life of the fan.

Regardless, every all-metal hotend (Hexagon and E3D v6) require a heatsink fan to further dissipate heat while the hotend is in use, warming up and cooling down. If not, the filament in the hotend will swell or melt, but ultimately clog. I hope the OP isn’t confusing ceramic hotend designs, which may not require a fan.

So I’ll contribute an idea to the OP’s goal… you could steal the fan control from the 2nd extruder on the Rambo. Ideally you’d insert a 5V voltage regulator (I actually think the little fan is 12V not 5V). The question would be the effectiveness of the varying the speed (which I believe is the varying of voltage) with the voltage regulator inline.

This may belong in another thread… but can I butt into the middle of this convo with a quick 5V fan question?

I bought a lulbotz Taz 5 all metal hot end but want to run it on my homemade printer. I got it all hooked up to a RAMPS 1.4 board perfectly execpt the 5v blower. I had to connect the blower to the servo pins. Is there a way to auto start the fan when ever the printer is turned on? Currently I have to type “M42 P4 S255” into the controller every time and its annoying. Can I edit the startup g-code somehow?

If this belongs else where let me know. Thanks.

I think it would be much easier to connect it direct to the 5V Pin of your RAMPS. On our TAZ it’s done this way on the Rambo.

Or as you said, insert your code into the start-gcode of your Slicer…

Everything above the heat cartridge is designed specifically to be most efficient at dissipating heat. Passive cooling alone was not enough so a fan running off the 5v rail was added.

There is NO benefit to allowing the heat sink part of a hot end to run warmer. It will only cause issues.

If you are having a hard time keeping your nozzle hot because of the heat sink cooling system, I would suggest you try another hot end that is capable of the temperatures you are trying to achieve, or that you are doing something very very wrong.