Bowden Tube Blower Extruder Cooling

thingiverse

As I have an enclosure for my printer, I prefer to keep it closed during printing to reduce noise and fumes, hence the name: en-CLOSE-ure. Even with one fan blowing in and one blowing out of the enclosure into a vent, it gets hot inside, causing the extruder to cool with hot air, leading to heat creep, resulting in a hot extruder motor that clicks and skips filament. Getting cooler air from outside the enclosure to cool the extruder using a blower and tube (Bowden cooling) is my next idea. A fan moves air but has little pressure to blow through things. If you tape a funnel to a fan, very little air comes out of the other end. A blower delivers high-pressure air but is often loud due to its high rotation speed. Using a large-diameter blower allows us to spin it slower and still have enough pressure. To make the blower: * Take a 12V, 12cm or 14cm fan and break off the blades - wear safety goggles! (See pictures; the round label is from my used fan) * Remove the fan center motor from the fan frame (see pictures) * Print the bottom and top parts of the blower housing * Print the rotor (in pictures, you'll find two different rotors, one with curved blades based on airflow software design, generating less noise and a little more pressure. It's also very silent due to low rotation speed.) * Hot-glue the fan motor to the base * Test the position of the rotor with the top part closed before hot-gluing it to the motor. Position it carefully to prevent wobble and hitting inside parts. * Close the housing after testing with long 3mm bolts. Attaching the tube to the extruder: After finding a suitable-sized tube (blower side 28mm, extruder side 22mm), print the Tube Fan Adapter. The adapter has "blades" inside to guide and distribute airflow evenly over the hot end heat-sink. Remove the old 10x40x40mm extruder fan and replace it with the adapter. No printing travel will be lost in any axes. Mount the blower body to the enclosure ceiling after making an air inlet hole, and connect the tube to both printed parts. Old Extruder Fan to Einsy Board: To keep things even cooler, I replaced my Prusa extruder motor with a Zaribo extruder motor. It's a one-to-one replacement but runs cooler (see Flir Heatcam pictures). Results: To compare cooling performance, I heated the nozzle to 290 degrees, extruder fan on, and nozzle blower off. After switching the heater off, I measured how long it took to reach certain temperatures. The ambient temp inside and outside the enclosure was constant at 29.9 degrees. Swapping the 10x40x40mm fan for a 20x40x40mm fan gave the same results, but swapping the extruder fan for the printed blower solution reduced time to reach 50 degrees by 73 seconds (a 12% increase in cooling performance). In real life, the performance will be even higher since my enclosure typically heats up to 38-39 degrees Celsius.