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Prusament PETG stringing question  

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Grzegorz Gruszecki
(@grzegorz-gruszecki)
Member
Prusament PETG stringing question

Hi,
I'm experiencing an unusual amount of stringing when printing all sorts of models using black(ish) Prusament (Galaxy Black, Jet Black, Matte Black, etc.). However, this only happens when I'm using the 0.4 mm high-flow nozzle that came with the Core One.

After swapping to a regular 0.25 mm nozzle and running the exact same print at 0.15 mm layer height, there's little to no stringing at all.
Could it be that the 0.4 mm nozzle is simply worn out? There’s also a large buildup of PETG blob, but there’s not much I can do about that other than pausing occasionally to brush the nozzle clean.

Posted : 07/08/2025 8:28 am
Kieran
(@kieran)
Active Member
RE: Prusament PETG stringing question

Hello,
I am having extreme difficulty myself with PETG. I can't get a usable print out at all.
I to have the standard 0.4 nozzle that came with the Core One kit, but I've only had it a month, so I'd be shocked if the nozzle is alreday worn out.

I'm afraid I am too much of a noob to help you, but can I ask? would you recommend I get a 0.25 brass nozzle for PETG prints?

thanks

 

Kieran

Posted : 11/08/2025 1:06 pm
Grzegorz Gruszecki
(@grzegorz-gruszecki)
Member
Topic starter answered:
RE:

Well I find 0.25mm prints even with 0.15 layer height a lot less distorted. Stringing is almost nonexistent when i changed from 0.4 HF to a smaller nozzle. However a colleague of mine said it may be due to how a high flow nozzle is built and the way it lets the filament through. 

For sure you need to be aware of a fact that 0.25mm will increase print time significantly. I print for fun and my own use so a little extra time is not something g i worry about that much…

This post was modified 1 month ago by Grzegorz Gruszecki
Posted : 15/08/2025 6:41 pm
Scratcher's Guy
(@scratchers-guy)
Eminent Member
RE: Prusament PETG stringing question

Whenever stringing issues pop up, the first thing to try is drying the filament.  PETG, PLA - whatever you use to print with - strings less if it's dry.  I almost always print straight from a dryer, and that solves way more printing problems than the inconvenience of using the dryer.

Posted : 25/08/2025 6:27 pm
Steve
(@steve-5)
Estimable Member
RE: Prusament PETG stringing question

Another possibility, gleaned from other PETg problem posts (i.e. Prusament petg oddness), is you need to reduce printing temperature and extrusion multiplier (you can also try adjusting the retraction distances).  It seems that the default profiles are a little hot for the improved heat transfer of the high flow nozzles and the extrusion multiplier leaves too much residual pressure in the nozzle when the filament is retracted leading to the stringing and oozing.

Regards,

Steve

Posted : 26/08/2025 1:58 pm
Scratcher's Guy
(@scratchers-guy)
Eminent Member
RE: Prusament PETG stringing question

I second that. I was printing Prusament PETG CF with the HF .4 and the model, which has a flat top surface, came out really bumpy. I tuned the extrusion multiplier down to .95 and it was a much higher quality finish.

Posted : 26/08/2025 2:15 pm
Grzegorz Gruszecki
(@grzegorz-gruszecki)
Member
Topic starter answered:
RE: Prusament PETG stringing question

Ill be checking it now as i just got back from holiday. I got so many different PETG spools and print quality drives me crazy lately.

What about nozzle cleaning? PLA runs smoothly, PETG often fails to clean the nozzle and shortly after that triggers 'colision' error out of nowhere ;/

Posted : 27/08/2025 7:43 am
delcom5
(@delcom5)
Member
RE:

I’ve gotten excellent PETG prints by drying the filament, controlling the humidity in the room and adjusting the temperature +/- a degree or two from the manufacturer recommended temperature.

I use mostly Polymaker tho…due to Prusament wait time in the US.

 

Posted : 27/08/2025 3:06 pm
Grzegorz Gruszecki
(@grzegorz-gruszecki)
Member
Topic starter answered:
RE: Prusament PETG stringing question

Ok i changed to 0.95 and while printing big model its hard to say if its any better tbh. On top of that there is literally no comparison to 0.25mm nozzle in both quality and stringing. Unfortunately same print would take over 2x longer (1d5h). Ill play around with settings a bit more but it looks like the remaining PETG spools will most likely be the last i ever use. I may ask one of my colleagues who also happen to have a coreone to test my nozzle in his printer. It is really odd that PLA works flawlessly while PETG result in (i dont want to say pure trash) prints that are far from ideal.

Posted : 28/08/2025 2:28 pm
Diem
 Diem
(@diem)
Illustrious Member

HF nozzles are sometimes more susceptible to moisture problems - check your filament dryer is working correctly.

Cheerio,

Posted : 28/08/2025 3:25 pm
Grzegorz Gruszecki
(@grzegorz-gruszecki)
Member
Topic starter answered:
RE: Prusament PETG stringing question

i print straight from my Sovol drybox. And as said if not for the 2x longer print time i would be running 0.25 all the time because it never causes stringing. I wonder if it's due to 0.4 being a highflow nozzle 

Posted : 28/08/2025 5:26 pm
Grzegorz Gruszecki
(@grzegorz-gruszecki)
Member
Topic starter answered:
RE: Prusament PETG stringing question

I bought a fresh CHF nozzle from prusa and a test print ( https://www.printables.com/model/112181-complete-3d-printer-test-all-in-one-stress-test-be ) has NO string whatsoever. Must've been a really worn out nozzle i had that i had. I went through 11kg of filament (both PLA and PETG) since i assembled the printer.

Posted : 11/09/2025 5:14 pm
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