After weeks of messing around with settings, going over half a dozen of different brand of filaments, I think I have finally figured out the biggest issue of PETG quality (overhangs). It is all about cooling. Nothing else matters as much as proper cooling.
The only thing that people need to change is drop down part fan towards 0 (0-30) and turn on AUX fan (up to 100%). The default is the opposite - part fan high and AUX fan 0.
This could also explain why people are getting different quality results - because some people print in hotter environments and some in colder and some print with open lids and some with closed.
I will make another post when I pull together all data from all brands and see what is really optimal.
That’s awesome - would love to hear more. Does this mean that maybe the part cooling fan is strong enough to push the molten PETG but not cool enough to “freeze” it in place first?
Just a general note for anyone new to Bambu. If Bambu doesn’t sell a filament, it usually means they haven’t been able to really optimize their profiles particularly well enough across many brands, so you can probably expect a higher level of risk that the default profiles might not work super well. Plain, non-CF reinforced PETG is notably absent from the filaments that they sell.
I don’t think so, because even their PETG-CF profile for their filament can get better results with some additional changes. But there lies the first hint about cooling - their PETG-CF has much lower cooling values (0-30) compared to their generic PETG (40-90).
I can give some rough values I use for every PETG filament I tested so far and they all work about the same (Overture, Prusa, PolyLite, eSun):
Bump up bed heating a bit, so the parts really stick (75-80) if you use textured plate.
Increase nozzle temp to 265 for better layer adhesion and shiny look. Lower temps do not help for better quality, but just make the print less sturdy. I keep 1st layer at 255 to reduce oozing (because 1st layer is also slower).
Main part cooling min set to 0, max to 20. Set AUX fan to 90.
Set chamber fan to max (we want good ventilation around the part, but not directly on part); you do this with filament start G-code: M106 P3 S255
This should work for ANY PETG filament and massively improve quality (no more blobs that stick randomly around the part and filament strings that curl up). Overhangs are massively improved.
To even further improve quality, you can reduce speeds. Default Bambu print profiles are very fast and optimised for PLA. I am still working on that to see which speeds I should reduce, so it is good for overall any type of model. A quick change you can do is to simply reduce any speed (apart from Travel) to less than 200, set Outer wall to 100-150 and Top surface to 100-150. Generally, a 1/3 decrease compared to PLA speeds. Changing anything else has almost 0 effect on quality.
Print with open door and open lid in a cool room.
Let me know how that works for you. These changes made the biggest improvement.
What you recommend for speed would requiere him to have a custom profile, but max vol speed of filament will cap those speed at a maximum of arround 140mm/s with the defaut Bambulab PeTG filament setting (10mm³/s)
Unless he use layer haight < 0.2, reducing speed is not the good way IMO.
Reducing the max volumetric speed of the filament is IMO a better way, your profile will auto adjust its speeds based on filament settings and you wil not need to keep & update tens of print profile for each new filament.
The max volumetric flow is not a problem - I have fully tested Prusa and Overture, both have over 20+, so it is in-pair with PLA.
This is benchy with eSun PETG, only changed filament settings as described above and then printed with Standard profile (no speed changed). Just look at these beautiful overhangs. As good as when printed with PLA.
You missed my point, or yu misunderstood, or I have not well explained, does not matter
Was talking about this, wich is useless with a max volumetric speed that cannot enable such speed
EDIT: well to be more clear perhaps, he just have to reduce its filament max volumetric speed to a good value and he will not have to change any speeds on its print profile as they will adapt to its filament settings, got it ?
I have had excellent results with Hatchbox PETG and the stock profile. Here’s one of those random torture tests, hard to get a good image because of all the test bits, but that was printed using ‘generic petg’. The overhang capability is pretty impressive. The long bridge is 4" long. You can see some fuzz past about 70 degrees on the angle test. My latest issue with Hatchbox yellow PETG has been 90% solved using the textured PEI plate. Cutting the max nozzle temp to 250 and the flow to 0.9 got me the rest of the way. Otherwise, HB black, white, red, blue, gold have all worked fine.
I’m starting to print with PETG right now, great thread. Hoping my first print goes OK.
Based off what I read as the solution in the first post…
Does this mean that the Filament settings should include more settings overrides of the “Process” settings?
The slow down for overhangs is part of process settings, not in filament?
Benchy came out exactly the same. It is prob not a good test for it, because if you check speeds, only bottom internals actually reach 200+ when you set volumetric to 20.
Yes, it is an ugly print, but that seems to be an artifact of the original STL. Other petg prints I do have a very nice finish. I have about 50 hrs of petg printing so far, and the textured pei build plate is by far the easiest to print on. No gluestick, just works as long as you clean it regularly.
Also nice surface, touch. Sadly, it is out of stock for some days now already and I cannot buy more…
I printed this with “almost” stock profile. Set temp from 255 to 265, AUX fan to 30 and with closed chamber. I have also reduced speeds a bit because it was important to me to get this right.
Did you notice any blobs at the nozzle during this print? The filament is printing beautifully for me but I’m concerned with material gathering at the nozzle and ruining a larger print. I’ve watched closely and can’t tell if it’s oozing and curling up or if it’s “picking up” material it’s already laid down. Again, these smaller 1-2 hour prints have looked great but once I’m printing something over 2 hours, I’m having to pause and remove the build up from the nozzle. I’ve tested many different settings but the build up remains.
That’s the tricky part, the prints are looking great. The nozzle build up isn’t coming off on the print. It just slowly builds up over time. If the print is over 2 hours, I have to pause and remove the build up. If the print looked like junk, I’d have a better idea on what needed tuning. Since they look great, I don’t know what it could be.
So, any recommendation on infill type to use? Also, I enabled ironing. Once. Caused a total mess. Otherwise, I now seem to have PETG dialed in. Here’s one of my latest: Again, using Hatchbox PETG. A friend of mine that does a LOT of semi-commercial printing is raving about ASA. Anyone tried that?
