Topic: Aquarium pump + gcode fancontroll = awesome ;)
Hello everyone,
This is an invention to cool down the plastic that comes out of the hot end with cool enviromental air ( room temperature). Its is very good for printing small objects. Also I experienced that it's possible to print about 2cm in horizontal direction.
So you can setup the bridge distance in slic3r to a bigger distance (in some cases) and it's easier to remove these after printing :-)
The electric controll is based on the Gcode conrolled Fan Mod of Ian Johnson
( solidoodletips.wordpress.com/2012/10/26/gcode-controlled-extruder-fan )
but instead of a Fan i used a relais that switches an air pump for aquaria. there are really cheap ones for only 10€ ( about 13$).
I designed the Tubes and they really fit very well with a glue simply made of Aceton and ABS plastic.
Also it looks good when you paint them in copper or iron colours. ;-)
You need :
-Air pump ( i used a 66 Gallons/hour, 5Watt, Membranepump, bought at Amazon for 10€)
( amazon.com/s/ref=nb_sb_noss?url=search-alias%3Daps&field-keywords=air+pump+aquarium&rh=i%3Aaps%2Ck%3Aair+pump+aquarium )
-All the parts for Ians Guide ( but not the fan)
( solidoodletips.wordpress.com/2012/10/26/gcode-controlled-extruder-fan/ )
-12V DC relais (you have to take a look how much power your pump has to buy a relais that can switch that power.
-A flexible tube (inner diameter 4mm, outer 6mm)
-A glue that dry´s very quick. I used a acetone and ABS mixture.
For the electric part you just have to follow Ian Johnsons guide but instead of connecting the Fan you connect the 12V relais ( no solid state 
) . Take a look at the scam for detailed informations.
After the hardware is connected, its very important to set up the controll of your "fan" (in our case the air pump). I can only say how to adjust it in the Slic3r Menu (which Repetier-Host uses for example) : Go in your Slic3r Settings->Filament Settings->Cooling
Then you do the following adjustments:
-Fanspeed minimum to 99
-Fanspeed maximum to 100
-Bridges fan speed to 100%
-Disable fan for the first 1 layers ( maybe adjust to 2, you have to see how the layer behave)
I exchanged my Hot Head against this one thingiverse.com/thing:33152 from tek so if you have another hot head you may have to customize this Cooler tube system.
If you have any questions, just ask me.
P.S. :
Also it would be very nice if anyone has some improvements for this idea ! specialy for the electric part:
I know that useing an analog output to switch a relais is not what its made for, but i am no programmer for arduino boards so i had to use it like that )
Sorry for my bad english, but i learned it in school 10 years ago 
