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Not sure where to power cooling fan for MK8 extruder

Posted by Geartech

Geartech

Not sure where to power cooling fan for MK8 extruder
August 09, 2015 12:02AM

Registered: 8 years ago
Posts: 29

I just put a new MK8 extruder and stepper on my Prusa i3, the
extruder it replaced was also a MK8 but didn't have the cooling fan on the extruder drive.
It had the one for the print cooling fan but not the other.
My question is when should that fan be running, 12v from the P/S
or the fan drive from the Melzi board that drives the print cooling fan.
Forgive me if this is the worng area to post this question.

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o_lampe

Re: Not sure where to power cooling fan for MK8 extruder
August 09, 2015 02:00AM

Registered: 8 years ago
Posts: 5,232

For PLA printing it should be always on. I wired mine to the 12V pins directly.
ABS is a different story, some people use a thermostat switch to start the fan above 50°C ( probe on the heatsink ). Some don´t cool at all, but not sure which hotend the use.
-Olaf

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sarf2k4

Re: Not sure where to power cooling fan for MK8 extruder
August 09, 2015 03:09AM

Registered: 9 years ago
Posts: 476

The fan will always full on when I was using mk8, wire the fan to 12v supply. I think this is good to dissipate the heat since mk8 are attached directly to the heatbreak

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klausbfrederiksen

Re: Not sure where to power cooling fan for MK8 extruder
August 10, 2015 08:34AM

Registered: 10 years ago
Posts: 14

There is another connector for the extruder fan on RAMPS 1.4
Between X-axis A4988 driver and the 1N40XX diode near the power connector, there are 2 pins (may not be soldered in)
See [www.minuk.net]