Anybody here know what would cause the extruder gear to start grinding the filament randomly during a print. Ive had it happen within the hour and ive had it happen after 9 hours into a print. I cant seem to figure out whats causing it. I have no issues printing any other filament. This is Ziro gold PLA by the way. Im on my 5th attempt right now its been 7 hours and its holding steady. I disabled retraction entirely for this attempt.
only with that filament? i could imagine that aluminium powder particles(gold) have clogged the nozzle and after a retract or travel move it unclogged … the higher pressure let grind into it - you could try higher layers or more pressure on the extruder gear. Also possible is a weak spot within the filament.
I’d agree with @Ulrich_Baer . Only other possibility is heat creep but that seems unlikely unless your hotend fan stopped spinning.
Aluminum powder?! Dang im printing with a brass nozzle 
My experience with extruder grinding has happened when there’s excessive resistance to the filament passing through the nozzle; like from too low a nozzle temp for that particular filament, or a feed rate that’s faster than the nozzle can heat the filament (maybe the increased thermal mass of metalized PLA affects this), or a partial clog. I think I’d try raising the temp a bit to see if that eliminated the first rwo possibilities.
grinding the filament is a sign the extruder cant push it through the nozzle. maybe increase the temperature a bit? slow down a bit? make sure the nozzle is not blocked (do a cold pull).
You may be printing a bit cool as well. Try 210-215 C
Disabled retraction. Currently printing at 210 and it seems to be holding steady. I tried 212 yesterday with 0.8mm retraction set at 20mm/s but it started grinding after 20 minutes. My usual retraction speed is 35mm/s thou ive used it successfully up to 50mm/s on other filaments
@Cristian_Martinez It might be object related in combination with retraction. It was not clear in your description if you have tried this print with other filaments and you were successful or not. The fact that you turned retraction off and it is holding steady is a clue. I have seen instances where I suspect that retraction triggered heat creep was the cause. It happens when the retraction is too far (not your case) or to fast (Not likely but maybe…) or to often. Based on the geometry if you are retracting a lot you transmit the temperature of the filament up into the upper parts of the extruder faster than it can be dissipated and you get intermittent heat creep like symptoms.
I have had that happen when the filament I was using had “fat” spots in it. It would be printing fine then it would quit extruding and either start grinding through the filament or create so much pressure with my extruder that it would pop the bowden tube off the extruder.
Looks like a handy little machine. Gook workmanship. http://www.jetradar.com/?marker=167419
is it a geniune e3d? for a e3d never retract more than 1.5mm other wise it will jam in the cold zone.
My retraction was set to .8mm and yeah its a genuine e3d
@Jeff_Parish you might be on to something there. These are fan pieces for the jet engine model so there were definitely a lot of retractions