what are we really trying to acomplish with the cooling fan

If it's just to cool the filament as soon as it bonded to the part I am wondering if nozzles, similar to those used for coolant as used on a CNC mill, etc might be worth a try. This would provide a very focused stream of air, not always, but most of the time right where we want it.

If you want to run air compressor I suppose that would work fine but I would probably use something like a fish tank air pump. I usually run ABS so I don't have a fan to cool the part

good suggestion about the fish pump. although the air compressor is 10 feet away

I have tried using nozzles as well as a ring jet very close to the nozzle. My intention was to cool the extruded plastic to a point where it was solitd enough to resist creeping, while hot enough to minimise distortion.


Also seen in [www.youtube.com]
You will notice that I also use the exhaust from the heatsink fan directed against the (insulated) square block of the heater - this creates burble - turbulence which gives a better distribution of air. That does work well.

The air ring looked like this



Although I use the air ring, my conclusion is that is isn't snake oil (doesn't cure all ills). For both the nozzle and air ring setup the optimum flow seems to be about 4 liters per minute.

Mike

edit: in the sectioned picture I show Tecapeek used for the tube to the hot end. This was a failure DO NOT DO IT.

Edited 1 time(s). Last edit at 04/13/2014 05:01AM by leadinglights.

Nice work. The quality on the video looks great. I'm working with very small parts (around 1 cu/in). I think I might try a version of your ring but with a tapered (offset) cross section with a very focused air stream

Last year, I used an iwata airbrush pump to put air where I needed it. on the cold end section right above the hotend. it was noisy, and didn't help eliminate jamming.
I'll try to dig up a picture shortly, of the CAD image at least. I was thinking this would be a good way to bring cold air into a heated build chamber. not sure it's necessary to do this.
I also tried a lumbar air pump from a Ford truck (low flow) and some ebay air pumps, plus a Keurig pump from a dead coffee maker. This cold directed air idea just stopped for me.

I like a simple fan flowing over the extruder motor, because on long prints, the motor heats up and the since it's a direct drive setup, the PLA softens at the pinch wheels.
I turn off the extruder motor when not used, so that helps reduce heat if idle.

Also, very well known, the fan flow is useful to cool the printed part to prevent sag, when the heat builds up in the print.

Finally, the cold end heatsink always benefits from flow.