Circular fan-duct for blower for this carriage http://www.thingiverse.com/thing:1275203. Made for the common 50x50x15 blower by Sunon. The blower is simply fixated by a snap-in fitting. No screws are required.
The benefit of a circular fan is a confined, symmetrical and downward facing air-flow. No dead zones are created. See also this awesome investigation by Desi Quintans http://www.desiquintans.com/coolingtests2. In contrast to the surround duct investigated by Desi the duct presented here has a tightly focused airflow, thus probably being a combination of a sharp nozzle and surround type. Nevertheless check the attached experimentally visualized airflow by means of smoke demonstrating the focused, confined long range airflow.
Why using a blower/radial fan? A radial fan has a lower airflow but has a higher pressure as compared to an axial fan which makes it the right choice for high-flow-resistance ducts like this one.
- Added a version (v2) with additional mounting option to pull up the duct on the back side by a rubber band or a string.
- Added a version (v3) which also cools the throat of the hotend. The bottom exit holes are made larger to compensate for the loss of pressure in the duct.
- Added a throat nozzle to reduce throat cooling.
Printing of the circular openings is not easy. I suggest printing quite cold to have good bridges. I print with PLA at 175°C.
Please select proper printing orientation.
You might want to clean the small circular openings with a tiny metal screwdriver.
I decided to keep the output openings close to the nozzle to cool only the freshly deposited filament. I did not want to cool the heated bed. Furthermore, I did not want to cool the nozzle by the airflow to allow for variable cooling.