So my X1C is not my first printer by any means. I have 2 heavily modified ender 5+ running Klipper so im not new to 3D printing just bambu lab printers and PETG.
As the title implies I keep getting build up of PETG on the nozzle that leads to stringing, underextruded layers, and eventually blobs. It sounds like the nozzle is digging into the print resulting in the build up.
I have done all of the filament tuning steps for this filament (temp 245, flow at 8.25 down from 9.0). I have the AMS loaded up with desicant for the last 2 days sitting around 15% ish humidity so its not wet filament.Doing the filament flow calibration with the lidar at the beginning makes 0 change to the situation.
The way i am printing the part there is only walls, no infill since I want the part solid. I have checked the avoid going over parts option also no change. Normal speed or silent I dont see much of a difference in quality or how much builds up on the nozzle. I have had 0 issues printing PLA for the mods for the AMS but unfortunately I specifically need PETG for this project since its going into a fish tank.
Is there a way I can adjust the Z offset to raise the nozzle a fraction of a mm to try and avoid the nozzle from scraping. Im used to doing this function in moonraker or the touch pad.
The AMS is not a filament dryer. It will keep filament reasonably dry for a longer period of time than just leaving the roll in the open. But it doesn’t dry (or if it does, it will take an extremely long time).
PETG gets stringy if it oozes. Dry it properly, in a dryer, 65-70ÂşC for 24 hours to be really sure, and try again.
As others have pointed out - the AMS isn’t a filament dryer. Make sure to dry your filament well. PETG is even more sensitive to moisture than PLA is. I try to keep my humidity sensor reading 10% (which is the lowest it’ll show on my model). If it get above 10% I change my desiccant with fresh and recharge the old. Something to keep in mind when talking about humidity and how dry (or not) the environment is - humidity is relative to temperatures so 15% humidity at 18 degrees is much less moisture in the air than 15% at 30 degrees since warmer air has a higher moisture capacity.
Too much moisture isn’t the only possible problem here - but it’s the easiest and most straightforward to resolve if it is the issue. And what you are describing could easily be explained by filament that isn’t dry enough.
You may want to double the time as well as enabling moist air to escape during drying (my dessiccant will also dry at 70°C, so it’ll not do anything for the air humidity until it cools): Filament Drying Recommendations | Bambu Lab Wiki
Even with a good amount of desicant loaded up in the bowl as well? The humidity in the room is about 40%. I put my hydrometer underneath the bowl and its down to about 25% at 110F
25% humidity at 110f is a LOT of moisture in the air.
Yes, you need air flow. You can take a box like what Bambu filament comes in, cut the top off, then poke a few holes in the bottom of it with a pen or the Alan key that came with your printer and then place it holes up over your filament.
I dry PETG like this at 65c for 6 hours and then flip it over for 6 more when using a printer bed to dry. I tried to attach a picture but makerworld is complaining about the megapixels and I don’t know how to adjust that down to get it to post.
I’m not sure if the desiccant in the middle will do anything as far as drying the filament is concerned, but if it doesn’t help in that regard it should at least be recharged by the time the filament is dry.
And that’s exactly what I had in mind. That’s my preferred way to dry filament and it actually works better than most out of the box filament driers.
I truly hope that this helps with the issues you are seeing.
That’s the exact problem with many filament dryers. They don’t allow any or enough airflow.
There are videos and write ups that explain why that’s important that do a better job than I could so I won’t bother. The short version is that your print bed with a box over it will work significantly better than a filament dryer with no airflow.
For desiccants like silica gel, you heat them to regenerate them. Their water capacity goes down as you heat them. If you heat desiccant with your filament in essentially a closed container, the desiccant needs to very, very dry because the heat compromises its ability to absorb other moisture. It can work but it needs to be fresh.
You don’t want to do that. Desiccant packed with the filament will be carrying a water load just like the filament. Actual amount of water will be different but they will have equilibrated together in the bag.
If you want to put desiccant in there to soak up liberated water, it needs to be fresh or at least at a lower equivalent water content than the filament.
