I am currently printing with dried FIBERON PETG-rCF filament. At the beginning of each layer (seam), I noticed stringing. On round elements, I set the seam to random. At the moment, I have only changed the temperature to 275°, with no visible changes. I found information online that the reason for this print may be incorrect retraction settings. I have not changed anything here. Can anyone advise where to experiment and whether I will find these settings here?
PETG can be quite a diva. PETG-CF is much more forgiving, but I dare say typical PETG precautions still hold.
Most importantly, PETG (and PETG-CF) really needs to be dry. Since the bags do allow moisture through, it is best to dry the filament upon opening the bag.
Next, PETG has a few further very annoying characteristics:
It loves to warp and curl
It loves to stick to stuff (in particular the nozzle, less so to itself if too fast or too cold)
It really likes to take its time to cool
Regarding the latter item, I have found enabling “Wipe on retract” to help a lot for all of my PETG prints.
As for the other items, one of the most effective solutions is usually to keep printing speeds below 80mm/s (while using the “Generic PETG-CF” profile). It may be annoying for prints to take longer, but I at least prefer one good print to three bad ones in the same time.
Alternatively, a lot of tuning can be done to achieve higher speeds, but there are many parameters to consider with PETG as all of the cooling parameters need to match speeds, flow, etc. Usually, it is much easier to just slow down.
People generally have the wrong expectation with respect to retract. Even melted, the filament is very, very viscous. Thick fluids with high surface tension don’t flow through small apertures on their own. The filament has to be driven out. Moisture in the filament is the only way that can happen (assuming the extruder motor isn’t running).
No filament is ever completely dry, so some small amount of ooze is going to happen no matter what. If the ooze rate is low enough, though, it doesn’t matter because the nozzle isn’t ever idle long enough during a print for any appreciable filament to ooze.
So if you’re still getting print defects that incline you to think you need more retract, the odds are much much better that you simply need to dry the filament more. There is no magic number for how long it takes to dry filament out. Depends on the filament, environmental factors, and the dryer. Whatever time and temperature you used may simply not have been enough. I don’t try to store my filaments “dry”. They’re in bins in my basement which has a dehumidifier, but I always dry prior to use. With the exception of PLA that I run at 60ºC, everything runs 24 hours at 70º prior to going in to the AMS. And if it stays in the AMS more than a few weeks, I will take it out and dry it again even if the AMS is still “happy” with humidity. Over time, moisture gets in and the dry filament and desiccant both fight to absorb it. Both get some, humidistat goes down even though the filament moisture level has gone up…
I havent direct experience with fiberons PETG-CF but 275 sounds real hot for PETG-anything. Being extra hot for the material makes any moisture problems extra present. I’d unspool 20g of it, send the rest to the dryer, and then run a benchy/temp tower with that handful of filament at 255C just to see if temp isn’t exacerbating your problem.
Thank you. I will try to dry it more I did print same models with BambuLab PETG HF … the came out perfect It’s just a shame that to buy this filament in the EU, you have to hunt high and low and really hard at that because stock disappears in 10 minutes, even from shopping cart.
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