Notifications
Clear all

Prusament PETG settings to reduce stringing  

  RSS
Kirinya
(@kirinya)
Active Member
Prusament PETG settings to reduce stringing

I've been playing with the filament settings to reduce stringing on Prusament PETG on my MINI+, and these are my results so far. I've gathered and made adjustments based on many forum posts all over the place, each usually mentioning a couple different settings.

I've made a lot of progress, and not sure if it can still be further improved?
I'm curious if anyone else has had more success, and what settings you've changed to get there.

Test print: https://www.thingiverse.com/thing:909901

Right: stock Prusament PETG profile (250C)

Left: 

  • Extrusion multiplier: 0.95
  • Nozzle Temperature: 230C
  • Retraction Length: 6 mm
  • Lift Z: 0 mm
  • Retraction speed: 30 mm/s
  • Retract amount before wipe: 25%
Posted : 08/07/2021 3:34 pm
Kirinya
(@kirinya)
Active Member
Topic starter answered:
RE: Prusament PETG settings to reduce stringing

My larger actual prints still have worse stringing than this test model shows, and at a level where I still have to cut and sand to even look decent. I would like to get those to print better. Unfortunately I don't have any pictures of them straight off the print bed at the moment.

Posted : 08/07/2021 3:47 pm
fuchsr
(@fuchsr)
Noble Member
RE: Prusament PETG settings to reduce stringing

I can't see the picture?

Posted : 08/07/2021 7:09 pm
Kirinya
(@kirinya)
Active Member
Topic starter answered:
RE: Prusament PETG settings to reduce stringing

That's strange.. the image showed up for me. But after relogging in, it's gone.

I've uploaded to imgur (link in case image below still breaks)

Posted : 08/07/2021 7:29 pm
Kirinya
(@kirinya)
Active Member
Topic starter answered:
RE: Prusament PETG settings to reduce stringing

Here's a print fresh off the bed though. Still lots of stringing.

This post was modified 5 months ago by Kirinya
Posted : 10/07/2021 4:39 pm
bobstro
(@bobstro)
Illustrious Member
RE: Prusament PETG settings to reduce stringing

I don't have a Mini, but things that have helped reduce stringing with PETG the most for me have been:

  • Ensure the PETG itself is dry. Before making any other wholesale settings or printer changes, I always dry the filament out. PETG is notorious for absorbing moisture very quickly (days or hours depending on atmospheric conditions). The stringing in your last picture is typical of the messy result often seen with saturated filament.
  • Tune the extrusion multiplier for each filament. A slight amount of over extrusion can contribute to fine stringing.

I've got more notes herethat might be helpful.

 

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 11/07/2021 4:12 pm
Kirinya
(@kirinya)
Active Member
Topic starter answered:
RE: Prusament PETG settings to reduce stringing

@bobstro

Thanks for the tips. I may have to try adjusting the extrusion multiplier then.

All my PETG spools were put directly into a drybox immediately after unpackaging, and has stayed at roughly around 20% humidity. So I think it's unlikely to be moisture? I don't have a food dehydrator, but I could try using my oven.

Posted : 11/07/2021 5:06 pm
bobstro
(@bobstro)
Illustrious Member
RE: Prusament PETG settings to reduce stringing

Unfortunately, it's hard to measure the moisture content of filament. If it was somehow exposed to moisture, a drybox usually won't dry it out. I always go with "when in doubt, dry it out". You can use an oven, but you have to be careful with temperatures.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 11/07/2021 8:34 pm
SEDAudio
(@sedaudio)
Active Member
RE: 0.6mm nozzle frustration

Interestingly I feel my Prusament PETG prints with a 0.4mm nozzle are pretty good with stock settings, I got marginally improved stringing performance by 3hrs drying the spool in a 60degrees C oven. Other than that I have yet to improve on the stock settings, with the caveat of sometimes having to slow down the first layer. 
However, my prints are not string free so I will try your suggestions. 

Does anyone have any recommendations for what to change in the 0.6mm nozzle profile? 
The quality of my PETG prints with this larger nozzle size is terrible, with tons of stringing, poor first layer quality with loads of ripples on large flat prints. 
I find it quite frustrating because I can't seem to narrow down if I need to change some combination of first layer speed, flow rate, retraction, zlift etc to get better results. 
Changing the first layer speed to be a very conservative 16mm/s has help improve the first layer quality a bit, but its by no means solved, and 4mm retraction and 2mm zlift doesn't seem to have helped stringing at all. 
Is 250c too hot?
Is the stock mini print fan too weak?

 

This post was modified 5 months ago by SEDAudio
Posted : 16/07/2021 4:51 pm
fuchsr
(@fuchsr)
Noble Member

Did you do a first layer calibration after swapping nozzles? I swap nozzles frequently, and in most cases I didn't find it necessary but I always watch my first layer and adjust Live Z or redo the first later calibration with the new nozzle, in case the swap affected the distance to the bed. And PETG is less forgiving than PLA. Of course you need to slice a calibration square using the 0.6 mm profile. The built-in routine  is only for a 0.4mm nozzle.

Posted : 16/07/2021 5:07 pm
SEDAudio
(@sedaudio)
Active Member
asd

Hi @fuchsr 

I did a first layer calibration using the stock first layer control, as you say that is for 0.4mm.
Perhaps I should slice a calibration for with the 0.6mm nozzle settings, thats a good idea! 
Here is an example of a print I am running right now.
The stringing is terrible, though I didn't pre-dry the filament this time 🤔 

Posted : 16/07/2021 5:27 pm
fuchsr
(@fuchsr)
Noble Member

If you want to see terrible, try wood filament...

Seriously, from this picture, yes, it's more than what I usually see with PETG on the Mini but not as crazy as I expected. Debugging stringing is a tedious exercise, with many recommendations you can find on what can be tried to minimize it, and often totally contradictory. I usually get by by just putting the heat gun to it...  I just re-discovered a similar thread from a few months back: https://forum.prusaprinters.org/forum/how-do-i-print-this-printing-help/stringing-cant-figure-out/ Maybe something in there that might be useful.

Posted : 16/07/2021 5:57 pm
SEDAudio
(@sedaudio)
Active Member
Wood?

Ok so the stringing of this print isn’t going to stop the print from being usable, but what if it was a small gearbox for example (I wouldn’t print such a thing with this nozzle anyway). 
You think the heat gun is a good solution? I should give that a try!

I guess I just wanted to learn how to get the best performance from my printer, though I appreciate that does require effort on my part. 
Do you have any further recommendations not listed here?

Posted : 16/07/2021 7:40 pm
fuchsr
(@fuchsr)
Noble Member

I found a heat gun to take care of most of the stringing I see with PETG, occasionally needed to do some sanding.

To optimize the print parameters may take a while as there are so many parameters to consider. Listing them here serves little value, feel free to do a google search, and you will find thousands of hits. I may have a sarcastic perspective on this, but you'll find everything under the sun listed as "the" solution, including increasing the print temperature and reducing the print temperature, raising retraction and lowering retractions, etc etc. I guess what that shows is that "the" solution doesn't exist, it's probably a combination of factors specific to the hardware, filament, and model at hand. I usually prefer to live with some stringing when it occurs and only engage in optimization efforts for the rare large production run (I don't run a commercial print shop but sometimes produce larger quantities of objects for my fellow dog trainers). Bobstro's notebook is a great starting point for trying to figure this out (and for many other things as well!).

Posted : 16/07/2021 8:05 pm
SEDAudio liked
Share: