[SOLVED] Bad quality when printing PETG

Because it is highly impacted by acceleration and speed if the value is set borderline - and with PETG it is always a bit difficult, especially at high speed (>80mm/s).

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I would’nt be so sure it come from a wrong PA as it appear not consistent over z Axis, but just in case, be carefull of not using too much light when doing autocalibration. this happened to me that nearly all corners disapear on my prints just after an automatic calibration while my secondary led lights was on, too much light can completly disturb the lidar (that problem have already been mentioned elsewhere)

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I tried to find that in bambu studio, without success. → It says this feature (manual flow calibration) is only available for the P1P, not for the X1CC. :rofl:

My take on your cube.
I’m using Prusa PETG Galaxy Black with slower printing speeds to get the desired results. Also changed the retraction length. See the outcome and my setting attached.
I normally do ironing on the top surface hence the low flow ratio on the top.








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I would suggest that @hant.szabi sends this print file (maybe better without flow calibration) to @T_guttata to make sure that there is no issue with the printer itself. I can also prepare a file if you like, just let me know what model you are printing.
Edit: sorry, I missed that you already shared the link to this model.

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This would be great!

I had the same problem with petg. Make sure that the petg is really really dry. After i dryed the filament for one day at 60 degree I the print quality is very good at standard settings in the slicer and it is possible to print in ridiculous mode with all brands I have. Before drying my print looks like yours.

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this is because of the high viscosity of PETG , under low layer height and fast print speed , the melted polymer will suffer high shear strain , some filament will have very large stress and break .
try lower the outer wall speed to 60mm/s

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Can you please provide more detailed information?

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Here is the 3MF file Dropbox - Quader30x30x30.3mf - Simplify your life

Drying is definitely a must for me! Brand new Prusa PETG filaments go into the oven for 6-8 hours at 60Cº. I had many issues initially, expecting the brand-new PETG filaments to be fine.

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Here we go. :slight_smile:
Printed with 0,16mm default profile on engineering plate (high temp plate would have been the better choice)):



Top:

Bottom (slightly warped, I was lucky it sticked to the plate):

Sides:


Links to my 3mf and gcode files, I forgot which is which…
https://drive.google.com/file/d/1ENAiGCfmyGbDcHL9s-5oaFWNfMW3ZUDV/view?usp=sharing, https://drive.google.com/file/d/1RBvVODK00Hap8C2PL5hcBdgxHXBM_J-s/view?usp=sharing

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Hi!

Quick notes on my findings as I use PETG a lot. I’ve only used Gembird PETG, and there’s a huge difference in the needed temperature for the same filament in white and black - I was expecting a difference but not that big.

I printed with Volumetric Speed 10 for both and white was okay for 220-230, going higher would decrease the surface quality.
For black, VS 10, temps were 255-260, anything under would get me the same results as initial photos from OP.

I just increased VS to 15 and also I increased the temps for white to 240 and black to 270.

Keep in mind that the faster you go the higher the temp needed, explanation here: Finding the correct slicer settings for printing fast | Bambu Lab Wiki

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This is exacly for this reason I have upgraded to a CHT nozzle, Speed impact less temperature. and does not need to be put too high with such nozzle.

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Ok, I printed with settings from hant.szabi and call that “9”

It’s way better and way slower. But: artefacts are still clearly visible.

I have not dryed the filament. If you need to dry it would mean you can not print it without the AMS?

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Default is to print outer wall first, but maybe printing inner wall first (outer wall last) would mitigate the artifacts? The theory being that there’s something to attach the outer wall to when it gets laid down. You can easily change this in the slicer settings. Regardless, it looks as though there is some kind of attachment issue in securing the outer wall of the cube to the inner wall of the circle, and once that fails, the failure compounds and gets worse with height.

The inner wall of the circle looks puffy on the right hand side as compared to the left. That’s what I’d focus on as the key to sorting this out. As was already pointed out by someone else, this seems consistent with filament whose moisture content is too high. Either dry the Prusament, or else try some other filament that’s fresh and dry.

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The AMS does not dry filament (unless there was literally water on it, then it would absorb the water once it evaporates instead of letting it sit in the air and soak your filaments). It only keeps it as dry as it was when you put it in there.

So you need to dry the filament either in a filament drier like the venerable Sunlu S1/S2, or you can use fruit drier, or you can use your electric oven (with care, it may not keep accurate temperature or radiate too much heat from one spot).

After you have dried your filament, load it into AMS and check that dessicant in the AMS is still usable. Some dessicants change consistency, like the ones included with AMS, some change color and some either do nothing, bulge up or disintegrate into dust. AMS also tells you if the moisture is getting high so that’s an indication that you should change it.
If printing without AMS, I suggest you get a filament drier - they are not that expensive and can also function as a filament dispenser, this is needed with some more extreme filament that soak moisture like nylon or CF, just make sure to unload/retract the filament back into the drier if you’re not printing or the length of the filament might still get moist and ruin the first layers of your print. But with PETG, you really just need to dry it once in a while and it should be fine, depending on whether you dry your clothes in the same room or something like that :slight_smile:

It’s clear the AMS does not dry the filament. But if you do a 20h print without the AMS, the filament will take the humidity in the air. I don’t know though, how fast this happens.

I will dry the filament in the Bambulab and try again.

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Drying the filament in the bambu? That won’t work out.

Put in the oven for 8 hours and 80C. This should get the potentially wet filament dry.

I tried the Sunlu S1, and for whatever reason it doesn’t do a good job of drying PETG.

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S1 only goes to 55ºC. I am by no means an expert in drying filaments, everything indicates it needs 70ºC. Not sure if it will never dry it, or just much slower, but it’s possible you just can’t get it to unbond from the PETG with only 55ºC or maybe just not dry enough. Also the S1 lacks a fan which could hinder it even more. Hopefully someone else will chime in.

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