can the hotend fan be temperature dependent

[pswindler]

Can I make the hotend fan dependent on the temperature of the hotend? Right Now it is on 100% all the time, i want to make the idle more efficient and less loud. It would be great to have it only turn on when the hot end is above 40* c. Any suggestions on where to start would be great!

[DeltaCon]

That is standard behaviour on a V2. I cannot imagine it is supposed to be different on a V3.
The fan turns on when you start heating the hot end. When you stop heating it does not shut down before the temp dropped to 50.
So, are you sure you didn't wire the fan to a permanent output?

[Bock]

The hotend cold side fan is permanently on when you have the accelerometer board. I don't believe that is adjustable due to the accelerometer board powering the fan using a constant 12v input. You would have to rewire the fan to the Rambo board on a separate pin and code it appropriately. I think a better solution would be to buy a quieter fan if possible.

[mhackney]

This is indeed the correct behavior on the V3. It is loud!

The issue is that the hot end fan does not have wires running back to RAMBo, it is constantly powered from the 12VDC to the PCB. There are three options:

1) a quieter fan (but I've never met a fan quiet enough!)
2) run a new wire alongside the whip for the fan + and pull ground from the PCB ground. Then you can use a 2 pin connector at the RAMBo end and use one of the available fan connectors. The firmware already supports turning on/off a fan at a temperature threshold.
3) install a small on/off switch on the HE280 "cap" and wire the + line to the fan through it. You would then have manual fan control.

Of these, 2 might be the easiest and least problematic. I used to forget to flip the switch back when I had a wired fan, not a pretty thing.

[pswindler]

Thanks guys! so my understanding is that cutting power to the fan will cut power to the whole board and vise-versa? gotcha, i like option 2 the best as well! thanks

[mhackney]

The power to the board is distributed to the fan, so yes cutting power to the board cuts the fan. Remember installing the fan leads and wrapping the extra around the top of the hot end? If you tap in there, you can cut power to the fan.

[Eric]

2) run a new wire alongside the whip for the fan + and pull ground from the PCB ground. Then you can use a 2 pin connector at the RAMBo end and use one of the available fan connectors. The firmware already supports turning on/off a fan at a temperature threshold.
3) install a small on/off switch on the HE280 "cap" and wire the + line to the fan through it. You would then have manual fan control.

As stated (2) wouldn't work. All of the Rambo mosfets control the ground pins. The power pins are always hot. If you do this, you need to leave the + side alone and run a private ground for that fan instead.

[geneb]

You could also install a resistor in-line with the fan power to slow the fan down a little bit.

g.

[mhackney]

Thanks and you are correct, it would require running an extra ground wire not a +.

2) run a new wire alongside the whip for the fan + and pull ground from the PCB ground. Then you can use a 2 pin connector at the RAMBo end and use one of the available fan connectors. The firmware already supports turning on/off a fan at a temperature threshold.
3) install a small on/off switch on the HE280 "cap" and wire the + line to the fan through it. You would then have manual fan control.

As stated (2) wouldn't work. All of the Rambo mosfets control the ground pins. The power pins are always hot. If you do this, you need to leave the + side alone and run a private ground for that fan instead.

[pswindler]

thanks for the correction Eric! that would have been a bummer to splice the wrong wire;)

[pswindler]

ok so what port should i plug the negative fan lead into the rambo? should i use fan1? I tried using fan1 and the fan would not turn on, so i am wondering if they left the same firmware controls in place, or will i need to modify them, where did the v2 plug the extruder fan?

[pswindler]

ok NEVERMIND, I solved it! For some crazy reason the v2 heatbreak fan was wired under the second extruder heater?? no idea why, but i plugged that baby into the negative terminal and it works like a dream, turns on and off at 40* c. no need to update the firmware.

[Noircogi]

That sounds like a nice mod, but the fan in the base is the loudest thing on my V3 and it's always on too.

I have a spare teensy sitting around, it might be an interesting project to put thermal probes in my power supply and SSR then switch the fan on and off based on that.

Do you have a Kill A Watt or other AC wall meter? I'd be interested to hear if the power savings is even measurable. My V3 used 11 Watts from the wall at idle in stock config (that's up to 18 with my 24V supply and 12V step-down regulator).

[pswindler]

I dont have a meter sorry, but i already put in temperature dependent fan controllers for the top and bottom fans, so now it is silent when on standby! They are only like 7 bucks from china (if you trust them) haha they worked for me thou i will post a link to what i used.

[pswindler]

here is the controller i used for the top and bottom case fans.

http://www.ebay.com/itm/181712653624?_t ... EBIDX%3AIT

[travelphotog]

ok NEVERMIND, I solved it! For some crazy reason the v2 heatbreak fan was wired under the second extruder heater?? no idea why, but i plugged that baby into the negative terminal and it works like a dream, turns on and off at 40* c. no need to update the firmware.

So am I to understand you found a way to have the V3 hot end fan act like the V2 fan, to come on and off with temp? Please tell me this is so. I have a few ideas but most involve running new wires like mentioned above. For now I am thinking to go with a Bendair and hijack the current layer fan outlet on the board and change the firmware to move it to the hot end fan. then direct connect the lay fan to the bend air. Let me know if you did indeed find way to control the V3 hot end fan. I love my V3, but that fan is like a plane taking off at times.

[mhackney]

Yes, this is so. But it requires running a dedicated wire to the hotend fan as it's new Ground wire that is then plugged into the RAMBo fan port.

I checked the firmware and it is still configured in there and is indeed set to turn on above 40°C.

[mhackney]

I'm writing up instructions on how to do this in my build thread, should be done in a few minutes.

[pswindler]

the only hard part was running the wire up though the wireing loom, had to use a stiff wire to push it though. other than that it is a very easy upgrade

[mhackney]

Yes that was the most difficult part. In my write up I actually use the Bowden tube to insert the new wire. That turned out to be very fast and simple.

[dkilduff]

@mhackney,
you said;

2) run a new wire alongside the whip for the fan - and pull ground from the PCB ground. Then you can use a 2 pin connector at the RAMBo end and use one of the available fan connectors. The firmware already supports turning on/off a fan at a temperature threshold.

which connector did you use on the RAMBo, and are you aware that if I wanted to do this on an H2 that it would run the same? which firmware supports this?

Thank you