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What do you guys make of this?

[img]http://hennekens.info/rostock/BW_Filament.jpg[/img]

My black PLA gets all white in the hot-end. Can this be caused just by the stretching while pulling it out? Think some piece is left as a clogg. This is happening constantly lately. After I stick in the filament and prime the hotend I can extrude without a problem. Even 10cm at once. But when I start printing it just clogs withing seconds. At first I thought it was because of the too small gap between bed and nozzle, since I had to experience the correct first layer height and minus z-probe heights settings after giving it fsr's. But I am pretty sure that's dialed in correct now. The PTFE was a bit bend at the hot end so I replaced it. Then I replaced the heatbreak because it suffered a lot of cloggs already and I tend to use the torch (which was never a problem before). Then I replaced the nozzle because during priming the filament come out if it a bit curly. So, Practically a new hotend, but still experiencing this. I even recently calibrated the thermistor and it operates within 2 degrees of my thermocouple. I usually print at 190 degrees, but the same goes when printing 200 or 220...

I am really out of ideas and want to get printing again.
Thanks!

What brand are you using?

Yeah, good question... I really have no idea because this spool came with the second hand machine and it is not labeled. That is probably a sign of cheap... Howevee I have used probably half the spool my self, on this printer, on larger objects too. You can see from the heavy curling that not much is left on this spool. Maybe I should try another.

Dismantled the hotend (again) and this is how it looks:

[img]http://hennekens.info/rostock/CloggedHeatbreakA.jpg[/img]
You see the whitened filamend stick out where it usually goes into the bowden tube

[img]http://hennekens.info/rostock/CloggedHeatbreakB.jpg[/img]
At the lower side of the heatbreak you see a hole were I assume the the rest of the filament drooled out. The nozzle itself has some filament residue, but "there is light at the end of the tunnel" so I am confident that the clogging did not start there.

How far does the PTFE tube go into the heatbreak of an E3D V6 normally? I measured a 34mm. I am not really confident that it inserted far enough previous to the clogging.

Never mind, solved it...
I you are interested how, please check this...
http://forum.seemecnc.com/viewtopic.php ... 499#p91499

But... Why did it turn white?

Qdeathstar wrote:But... Why did it turn white?

I suspect that with the PEEK fan not blowing, that it slowly decomposed the pigment out of the filament (Since black pigments tend to be quite low quality)

Qdeathstar wrote:But... Why did it turn white?

What Xeno said could be true, but I would not be surprised that the whitening is caused by the extreme stretching of the material. When I take cold unused filament and bend it, you can see discoloration very clearly just before it snaps. I guess the stress on the material while trying to pull it out at has a similar effect.