Compressed air cooling?

[greatmagnet]

Hi guys first post here, new to the world of 3d-printing awesomeness! I picked myself up a FlashForge Creator Pro over this last week and have ben loving it since I got it. =) Yes, Im still fine tuning, but I expected that. Anyway, after looking into alot of active cooling methods, I had an idea. What if you were to make a printed mount that would hold maybe a 8 gauge size needle pointed at the extrusion head. You would attach this to either a small airbrush pump or possibly even just a aquarium pump. In essence it would just be a precision air blast. Do you think this would have any added benefit over the fan powered type? You could even go a step further and make a printed ring with holes pointing in towards the ID to deliver air. Just an idea =)

[richardphat]

You can try it, but it might have a serious effect if you point toward the extrusion head. WHen you have compressed air that expands, the temperature usually drops below the room temperature. That will torture your printer, as it will draw much more current to maintain its temperature which means earlier component wear out.

That is indeed worth if you hate your printed object to shrink when you have fitting and don't mind doing extra maintenance on your printer.

[old man emu]

I hadn't considered temperature drop due to expansion (Boyle's Law).

My first thought was that directing a concentrated stream of air at a layer of molten filament would blow it all over the place (try it with a layer of toothpaste and a drinking straw), thereby ruining the form of your print. Don't forget that the air stream has Mass and velocity. The Law of Conservation of Momentum tells you that where the air stream collides with the filament, there will be a decrease in the momentum of the air stream and an increase in the momentum of the filament. Since the filament had zero velocity, relative to the air stream, it gains it due to the collision. Since velocity is a change in distance over time, bits of filament will move from their zero position to a new position after the collision. Result: globby print.

Old Man Emu

[jimc]

What you are proposing would certainly work but you are gong to need a real compressor. The cfm output if an aquarium pump or small airbrush compressor will not be anywhere near close to the air movement of a small fan. The other thing i am wondering is...what is the gain? Are you having a problem with the fan not cooling correctly and your looking for another solution? Like i said it will work with a much larger compressor but compressors are also very inefficient. The power required to run one compaired to a tiny fan is beyond way higher..... If the matters to you.

[T-MAC]

How much noise would a compressor that has a greater output than the fans make? Could be something to look into to modify an extruder and use a precision air blast (if not too noisy for a desktop unit) to cool the hot end instead of heat sinks and fans?

[richardphat]

Depends on the pressure chamber before the throat, you can reach Mach 1 easily running over 20+ PSI and when you have a sonic flow.... it makes sounds, lots of sounds.