Just bought the E3D V6 through E3D-Online (the knockoffs aren't worth the time I spent on them). The "always on" fan is pretty noisy, so I bought a replacement that is ultra quiet, same dimensions. However, the airflow seems to be about one-third that of the original E3D fan. (I don't have any means to measure either of them). Would I be putting my printing in jeopardy if I used this much quieter but much less efficient fan?
Depends on what you are printing. PLA is pretty sensitive to airflow and there isn't much margin even with the stock fan. Other materials with higher Tg are less sensitive, I've done ABS with no fan at all. Insufficient airflow will lead to jams.
Thanks for answering my question - and so quickly. Since most of my printing is PLA, I think I'll stick with the noisier stock fan for now. On a similar subject, why is it important to keep the fan always on? Is it the cooling down phase after printing that puts the printhead at risk? Could I not use the PWM fan terminals on my RAMPS board to run the fan, but then just use the Fan On gcode after my print to leave the fan on until I explicitly turn it off? Thanks for your studied opinion.
I like the blower fans. I could likely design a mount for it on the E3D V6. But are they much heavier? They of course need to be near the hot end, which is on a boom. On my printer, too much weight may cause extra jiggle during movement (a future design consideration).
Always on stems more from ensuring that folks don't connect it to the same header as a print cooling fan (which varies wildly in fan speed over the course of a print). As long as the fan is on full blast when the heater block is over ~50C, all is OK. Some controllerboards/firmwares can handle this automatically. Marlin/Rumboa and RepRapFirmware/Duet or Duet Wifi are two that come to mind.
I rigged up a mount for a blower fan. It's a very light fan, lots of throughput, currently hooked up to "always on" power. I may experiment with the print cooling fan - I use Marlin software, and I think I found the settings for the 50C you mentioned. Thanks!
The heatsink fan is there to stop filament going soft and/or molten in the heatsink area of the hotend, otherwise it will jam. There should be a sharp temperature gradient between the heater block (where the filament should be molten) , and the heatsink (where it shouldn't). The heatbreak is where this delineation should take place, and the fan is there to make sure the heat does not travel up past the heatbreak