Fan for the extruder?

[Andrés Ayuso]

I read in the wiki.arcol.hu page of the hotend v.4.1.1 and 4.2  that a fan is mandatory if you intend to print with PLA but, the fan should point to the print bed, the nozzle or the heat sink of the extruder ?

My question could be some obvious but makes a doubt for me...

Thanks in advance

[Ronald Aldrich]

Ideally, you'll want both.

A fan is needed on the nozzle's heat sink, because you need a sharp transition from hot to cold inside the nozzle in order to prevent backpressure from forcing PLA up into the cold end of the nozzle.  This isn't an issue with ABS, because ABS is much more viscous than PLA at extrusion temperature.

A fan is needed on the print, when you are printing small objects, because otherwise the plastic will retain too much heat, and remain liquid from layer to layer.  You can avoid needing a second fan by printing multiple objects at once, or by slowing down the print so that it has time to cool naturally from layer to layer.

- Ron

--
If you want to send a message to this group, please send the email to arco...@googlegroups.com
---
You received this message because you are subscribed to the Google Groups "arcol_hu" group.
To unsubscribe from this group and stop receiving emails from it, send an email to arcol_hu+u...@googlegroups.com.
For more options, visit https://groups.google.com/groups/opt_out.

[Ante Vukorepa]

You don’t need separate fans, though.

You can have one fan covering both. The hotend has enough power that the slight draft over the heater block won’t cause much trouble. If it does, just wrap it in some ceramic insulation.

Alternative solution (i’m using) is having two fans, one on each side, both directed at the tip of the nozzle.

One of those has a duct directing the air at the print only. The other is covering both the print and, with a slight draft, the heat sink (most fans have a “hole” in the center, inside the air vortex, so if you position the fan carefuly, you can get that “hole” aimed at the block).

The reason for using two fans is that sometimes, on complex prints, the print itself blocks the air from reaching the other side, so you end up with curling on one side and no curling on the other, or possibly other artifacts too due to the constant temperature differential.

-- 

Ante Vukorepa

[Laszlo KREKACS]

Hi,

As others have said, you only need a small airflow to prevent hot
building up in the heatsink.
It is especially a problem with slow small prints when the hotend
stays longer at the same spot.

Laszlo

[Andrés Ayuso]

OK understood

Thank you very much