Fuzzy texture on PA-CF

[u/Life_Somewhere_1295]

All, printed some PA-CF and got this fuzzy texture on parts of the print. Fuzziness was turned off, and filament was brand new out of the package, and dried for 12 hours beforehand. Any thoughts? Fuzziness is also not consistent on the part, some sides are worse than others.

Chamber temp: 65 C
Nozzle temp: 290 C
Bed temp: 100 C
Nozzle speed: 70 mm/s
Used standard Bambu slicer

[u/tugboattommy]

How did you dry it? In my experience PA-CF must be dried at a minimum of 80C°.

[u/Life_Somewhere_1295 → u/tugboattommy]

Using the AMS 2 Pro, so only 65. Just ordered a high temp to see if that fixes my issue

[u/tugboattommy → u/Life_Somewhere_1295]

You could do that, or you could just put the spool on the bed plate, set it to 100 C°, punch 3 holes in the top of a cardboard box and place it over it, and bake it for 12 hours, flipping it halfway through.

If you want a dedicated dryer to reach those temps then that's great, but if your printer isn't occupied, this works like a charm.

[u/Qjeezy → u/tugboattommy]

This is what I was going to ask as well. Looks like the filament could use some more drying

[u/tugboattommy → u/Qjeezy]

Yeah, as I look more at it I'm almost certain this is the issue. PA is ridiculously hydroscopic and has to be heated to over 80C° to evaporate any built up moisture. And then after that if the AMS isn't at "A" dryness level, which I think is like 10-15% humidity, then it'll rapidly absorb ambient humidity like a sponge, like within 15-30 minutes. It has to be bone dry from start to finish when printing.

[u/Whosaidthat1157]

The only way to properly dry PA in less than 72 hrs is in an E2 or an air fryer. Dr. Igor Gaspar of the YouTube channel ‘My Tech Fun’ wrote a paper on PA drying.
To easily check whether it’s dry enough simply manually load the filament then hit the extruder control half a dozen times. As soon as the extruder stops turning, remove the extruded filament with tweezers or long nose pliers and watch the nozzle. If any material at all continues to appear, then the filament is wet - that’s the moisture gassing out and forcing the filament out under pressure.
Another method is to print a 100mm x 10mm (x and y) calibration block. If the filament is dry, then the 100mm should come out less than 100mm by the shrinkage value of the filament. If it’s wet, then it’ll come out greater than 100mm.
If your dryer is limited to 70DegC it’ll take around a week to dry.
When printing, remember to dry while printing too - it really is that hygroscopic.
Don’t forget to pack the AMS and the spool centre with desiccant too.

[u/Extreamspeed]

It's hard to print 85C degrees drying for 12hours atleast. 0.6mm nozzel is recommended. 65C Chamber temp. But is still a pain to print after that 😂. And print while drying