Hello I’m kind of hijaking because bambu has infinite wisdom and won’t let someone with 2 bambu printers and a mountain of filament post new topics it seems… but my issue may be related to maintenance too…
I’ve made several large prints for a table top game in PLA, and I’m trying to switch to petg which looks awesome where it prints correctly… this print looked fantastic till it started destroying the top layers… OH GET THIS I CAN"T EVEN UPLOAD ATTACHMENTS WILL SOMEONE PLEASE SLAP BAM DOO DOO PLEASE
Unfortunately, there’s so much spam etc around that forums need to take some spam protection measures ( Understanding Discourse Trust Levels). But they are not overly difficult to meet.
You already have the 10 Min reading time, so it is probably only a matter of entering and scrolling through a few more posts (maybe search for “PETG” in the forum?) or needing to wait for the system to update (which can be forced by logging out and in again).
As an intermediate aid, I have found it rather important to use newly dried PETG. It is frequently moist, especially if new! It has spent weeks at sea in bags that slow but do not stop moisture ingress…
Moisture can lead to a number of things. Curling, for example. This in turn causes nozzle collisions, toppling supports and ripping layers apart.
This. And it can be true with other materials as well. (I know you know this, Eno - for @user_3667010179)
It’s very misleading for most that the filament comes vacuum packed in plastic bags with a sachet of desiccant. People look at that and think “it’s dry as desert bones” when it frequently is anything but dry.
Why? Those bags are “semi-permeable”. They let some stuff through (like water vapor) and not other things like O2 and N2. Why? Water is a very small molecule. O2 and N2 are significantly bigger. You can block water more effectively with thicker plastic for the bags and a metallized coating but those get expensive. They have to pack the really hygroscopic stuff in thick-wall metallized bags though.
The standard plastic bags used with filament have pores that are big enough for water to eventually wiggle through. So here’s why the bags are confusing - since O2 and N2 don’t leak in as easily, they still put pressure on the outside of the bag and make it look like it’s still under “vacuum”. People see the bag collapsed around the filament and think it’s dry.
The reality is water has been leaking in since it was bagged. That desiccant packet helps grab some of the water but it still divides between the filament and desiccant. The partial pressure of water vapor in the bag can rise to match ambient but the excess pressure on the bag by ambient air pressure hides that. It still looks like it is under some level of vacuum when the reality can be very different for what matters - water vapor.
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