Hi, i need your help. I bought some petg hf. But i really dont get it to print straight walls. I get a lot of layer lines visible on my A1.
The roll is dried to 14% for 30hr now. I tried with different infills, normal and gyroid, i tried with very slow outer salls (50mm/s), 100% speed and 50% speed. Did all possible calibrations, tried a second roll of petghf, tried different models but the results at the 90degrees walls are always like this. Any other ideas?
My Flowrate is at 1.02, but i tried 0.99 /0.98/ 0.94. Temperatur is at 240, and i tried 235 too.
4 & 5 outer walls. Testet with outerwalls first too.
Also on the 45Ā° angle it looks very clean and good.
The only thing that I can spot immediately is that you seem to be printing rather cold for PETG.
Another item to check is layer height. A smaller layer height and speeds below 100mm/s have helped me many times (but that is on the āclassicā PETG, I did not try much with PETG HF yet).
What profile are you using in Bambu Slicer? Including plate type, etc.
It sounds like youāre using a custom profile - let us know what numbers youāre using.
My gut feeling insufficient cooling and/or excessive volumetric flow rate for the type of PETG. 4-5 walls sounds excessive for a lot of uses - itās certainly possible to tune for that, but itās a lot of hot plastic concentrated in one place, and the wall speeds may have to be turned down even more than usual in order to ensure that the plastic cools down faster. This really looks like the plastic isnāt completely cooled enough every layer and prints are too fast.
For reference, Iām pretty sure the default wall loop setting is typically 2 walls. More definitely increases strength, but for most materials you end up needing to do a bit more tuning.
I started withthe 0.2mm strength profile, lowered the speed from the inner and outer walls to 100/200, and the outer walls to 4 and 5. Used 30% infill, outerwalls first, and then the bigpart i printed even with 50% speed. So speed couldnāt be an issue.But i follow this outerwall thing and reduce it.
Speed can not be an issue,as i lowered it to 100/200 outer/inner and then printed the whole big thing in 50% speed mode. Lower the layer height would be a problem, because I normaly print very big parts.
Which material profile? Many of the relevant settings are in the material profile dialog.
Oh, it probably is related to speed and cooling unfortunately. They donāt tell you this but when you increase the density of FDM parts beyond the standard density, heat buildup can get significant and start distorting parts. 2 ā 4 walls is huge, and 15% ā 30% infill is also huge. I have done 4+ wall prints before and without tuning, even with a lot of brands of PLA, Iāve seen exactly the same type of layer lines that you see. I would consider at least going back to the default 15% infill, as most parts simply do not benefit significantly from more infill (if anything, more outer layers is better for strength than more infill)
Most of the time, I find itās a better idea to start tuning speeds with the filament settings using the maximum volumetric flow rate instead of speeds. To maintain high speeds even with the very high density part, try increasing the cooling settings (probably min fan speed threshold and max fan speed threshold) for PETG HF. Unfortunately, for some materials, this can significantly decrease layer strength, so you will have to experiment. The safer setting would have to be go decrease volumetric flow rate, but this will push your speeds down to something closer to what normal grades of PETG can achieve. I think you will probably have to do a combination of both. The default fan speed for PETG HF is very low so there might be a lot of room for improvement.
The layer height shouldnāt make much of a difference, 0.2mm is fine
It is better, some parts are even perfect, but still the walls a bit bumpy.
Always with 3 walls and 15% infill.
I tried temperatures from 235 up to 260, different flowratios from 0.92 to 1, cooling, gyroid&standard infill, different wall thickness, some low speeds, and readjustet the K-Value from 0.035 to 0.03.
I think I can live with the settings for this project, but I will switch to another petg brand the next time. My eSun hs walls are most of the time better than this, althogh all other parts are much cleaner with the petg hf.
Somehow it seems when i go lower with the flowratio (0.92 or even 0.9) the walls getting better, overhangs seem nice, But top and bottom layer has holes. How can i fix that?
I didnāt find a flowrate multiplier for top/bottomā¦
i would try printing with complete defaults - default printer, filament, and process settings (using 0.16mm High Quality for the outer wall speed reduction) and see if the visible defects are still present. if it looks good and you want more walls and/or thicker layers for the final part, add more cooling.
Thanks for the tip, i tried that one. Also with 0.12mm, it always looks the same.
I also tried the petghs settings from esun (which have perfect walls) and even tey look almost the same on petghf.
0.12mm layer height is pushing it for petg filaments from my experience. i havenāt successfully printed petg-hf at that height yetā¦i think drying and/or lower nozzle temps might be needed. been pretty satisfied with 0.16mm though!
I would start with drying the filament again. Check that you have a hygrometer the can measure %RH well below 10%. I had a similar issue with āwetā filament. I bought some PETG-CF and dried it till the hygrometer showed 13%RH. The result looked terrible as you can see in the picture.
Between the two prints settings have not been changed. It is just the same gcode-file stored on the A1 sd-card printed again. Now I dry my filament before printing down to at least 7 to 8%RH .
this is wildā¦thanks for that.Idonāt think i can dry so low here. In the end, my dryer was drying for more than 40 hours and still only 12%. So the only thing I can do seems to be forgetting about this petg from bambu and change to other brands.
The question is how low can your hygrometer measure. In my filament dryer (Creality Space Pi) it stops at 15%RH and does not go lower. I build my own Wifi hygrometer which can measure between 5%RH and 95%RH.
You can use dry air in your filament dryer to dry to low filament moisture anywhere regardless of ambient humidity. Ambient humidity imposes an artificial floor to how low you can dry to. A dry air purge removes that limitation.
You can generate a low flow of dry air with an aquarium pump, a straw to make the air flow through the desiccant, and a container of desiccant like silica gel beads. It works like a charm.
I created a print that puts it all together but you need to know how to do a little fine soldering but you can see itās just a pump, a straw, and a container of silica gel beads. It truly does work. Every time too.
I did print a model from Bambu Studio first.
When the job was completed, a message on the printer display asked me if I wanted to print the same model again, which then (for the first time) I confirmed.
When the model was printed the second time (only from the printer), the print had poor quality, almost like the filament settings were wrong.
While trying to find a cause, I realized that after loading the spool the second time (not AMS) I did not edit the filament settings on the printer again (I did the first time). The display still showed āPETGā (it never shows āPETG HFā), but when I selected Edit to edit the filament settings, the settings suddenly defaulted to āGeneric ABSā (or similar) instead of showing āPETG HFā as the selected filament. [BUG]
I noticed that during the first print job (sent from Bambu Studio), the display contents (layout) was completely different from when I selected āPrint the same model againā on the printer. Why?!
Several questions arose:
What happens with the printer when I unload a spool (not AMS), switch printer off and later on again and then load the same spool again. The display still shows āPETGā but what does the printer do in reality, does it keep the last filament settings (which in this case was PETG HF), or does it only show the name of the last filament on the display but use different filament settings (Generic ABS) instead? Which would be a bug.
Why was the print quality so different between the print job sent from Bambu Studio and the print job initiated on the printer by selecting āPrint same againā. Why is this not (exactly) the same? [BUG?]
Whatever the cause, itās weird that when selecting on the printer āprint the same againā results in a different UI on the display and totally different print (quality) result!
