Filament broke during long print

[AEK]

Hello,

Just curious why would the filament break during a long print.
I found the machine printing in mid air for hours until I stop it, I had not issues previously with smaller prints.
Made sure the Ezstruder gear teeth where cleaned, I always payed attention to that part, but you can see in the picture how it clogged up a bit during this print.
I originally though there was a tangled in the spool but there wasn't.

Rostock max v2 stock, Printing at 20mm/s with Simplify3D, PLA. X2 perimeters only no infill. retract is 5mm, 60mm/s. 190c / 50c.
I have one layer fan plus a small fan beside the machine blowing on it at low speed.

Any help would be appreciated.

Aek

[Nylocke]

You could try printing 5-10 degrees hotter and lowering the retract speed to 20-30. The filament is being ground up so there's either excessive back pressure (low temps), the drive gear is running along the filament too much/fast (lots of quick retracts over and over), or your hotend jammed partially or completely and the extruder continued to try and push filament through until it stripped it down (result of fast or long retracts with PLA, the guys at E3D explained this one pretty well at MRRF).

[IMBoring25]

Is your thermocouple still in good contact? Have you confirmed your PEEK fan is still running and blowing over the hot end in the correct direction?

[AEK]

Thank you Mike,
Makes perfectly good sense I can give that a try.

IMboring25,
The peek fan is blowing the right direction, I will be very surprised if the thermocouple is loose but will have a look.

[teoman]

I doubt it is the thermocouple, if that were coming loose the hotend would over heat.

You part does look like it would have a lot of retracts, so that probably chewed up thefilament. As it is a longer print, the motor heat creeping to the gear might have played a role.

So as Nylocke pointed out try making the retractions a little bit less aggressive.

Chech your motors temp, if it is too high try lowering the current or installing a fan on to it.

[AEK]

I always thought the retract speeds suppose to be fast, Will try slower.
Would probably prefer to install a fan than messing with current.
This 3D printing stuff is full of ongoing surprises...