Colorfabb PA-CF Low Warp will not print correctly

[TypeR]

Am trying to get my printers to work with the Colorfabb PA-CF Low warp filament.
So far, unfortunately, without success.

Layerheight 0.20 mm as per Colorfabb recommendation.
Printtemp from 255 to 285 degrees Celsius.
Retraction from just 1.0 mm to 4.5 mm.
Cooling fan from 0% (mostly) but also 10% or 20%.
Printing at 30 mm/s to 40 mm/s.
But no succes so far.
Nozzles both brass and steel, 0.4 mm.
Printers Mankati (once) and two Creatbots.

When heating up, the filament flows freely from the nozzle.

But after about 10-15 minutes, the flow becomes irregular.
When I pull the filament, the tip part looks very strange as you can see in the picture.
Have not seen any filament behave like this before.

Any one any ideas on how to get this working?

[wirlybird]

Are the extruders all metal type extruders or do they have the PTFE liners?
If they are not all metal hot ends then the temps are too much for the PTFE setup.

[TypeR]

Hi Wirlybird,

Yes, all my printers have a full metal hotend, I can go up to 350 degrees.
Tried on my first (eldest) printer which does have the PTFE-tube, but that didn’t work either.

Have orderd a 0.6 mm nozzle, perhaps that will solve the issue.

[wirlybird]

Are these printers Bowden or direct drive extruders?
I am wondering if it is a bit of heat creep considering the high temps.

[TypeR]

All these printers are Bowden printers.
Being relatively large printers, there might be an issue with friction in the PTFE-tube leading to the nozzle since this is probably longer than average.
As for heat-creep, the Creatbot printers have a dedicated fan cooling the heatbreak (apart from the general fan used for cooling your print).
So far, the PA-CF seems to flow well even at 255 degrees and becomes very fluid at 285 but it still made no difference in the final result.
Retraction I uses was minimal, only 1.0 to 2.5 mm, specificially to avoid heat-creep etc.

[TheThird]

This might be a very late answer but today I was printing and the exact problem happened to me. After close inspection the filament absorbed so much moisture from the air and after drying it in the oven for about 8 hours @ 80 C it returned to its original stiff/rigid state and is now once again usable.

I hope this post shows up when someone is googling for this problem in the future.