extruder fans

[anthony27]

Hi Guys, me again!
I have noticed when I crank up my machine, and heat the extruders, their respective fans are definitely not spinning!
in fact I cannot remember them ever spinning, which is a bit of a worry , is it a maker ware issue do you think, or a hardware issue?
I am assuming if they don't spin, something will overheat? maybe this is why there are filament jams and blockages?
Also I may just go and purchase some new ones locally, i am away from my machine, what size do I need?
is there a way to manually test them?
many thanks for all your help in advance

[anthony27]

well after doing some research here are the possible causes that I know of:

-Overtightened bolts, stop the fans from spinning,
-Broken Mosfet conmnectors
-Wrong EEPROM settings
-Damaged cabling
-Makerbot desktop software settings
-DUD Fans-
-other?

[warkmal]

Damaged cables are high on the possibilities list. They tend to develop breaks where they flex on that post FlashForge zipties them too. In fact, one of mine cut out within a few print hours of getting the printer.

I think the firmware has a settable threshold for when they come on which defaults to 50 degrees celsius. There is also a gcode (and corresponding x3g protocol) to flip them on and off. I don't think Makerbot desktop emits it though.

[anthony27]

well I will find out tonight! it could be from the constant tearing down of the machine that they have been damaged, damn!
I wonder if it is worth swapping them out for better quality fans?
anyone know of the current specs, so we can compare with other possible replacements?

[anthony27]

In regards to the extruder fans what is their main function is it to cool the filament and stop it prematurely melting, regulate the temp of the extruder or cool the stepper? Or all threes
What hapens if they dont work and u print anyways?

[warkmal]

I believe all three. From what I understand, short run, more jams on long prints. Long run, premature wear on plastic extruder components.

[anthony27]

I believe all three. From what I understand, short run, more jams on long prints. Long run, premature wear on plastic extruder components.

Yep I think you are right!

[anthony27]

I believe all three. From what I understand, short run, more jams on long prints. Long run, premature wear on plastic extruder components.

Ok so Today, I thought I would try installing a new extruder fan as an experiment on the left hand extruder, to see whether it was the actual fans that were broken,
I used some two way connectors, instead of soldering,
I noticed the fans are still both not working! see images attached
20151002_201008.jpg
does anyone have any idea why this could be?
weird,
could it be a problem with the fet connectors?
the wiring?
the motherboard?
the firmware?
cheers
Anthony