I thought I’d come out here and ask for some experienced wisdom…
I’ve only been using my printer for about a week and been having fantastic results. I’ve mostly been using Bambu’s PLA. I wanted to print some spool core desiccant containers I found on printable, so I loaded a spool of Bambu’s PETG Basic. I printed one by itself just to double check the size and fit it into a spool in my AMS before I printed the other three. It was a two hour print and came out very well. So I sliced up a plate that had three of these containers on it side-by-side and felt confident to let it go for the full 6 1/2 hours while I was away from the house. I’ve always left the door closed when I’ve done my prints But thought I’d mention that this is the longest print I have ever done and the door was closed the whole time so I don’t know if that would’ve made any difference since the problem seem to develop near the end of the six hours
The picture below shows the result. While the containers are certainly usable, aesthetically they lack the perfection of the first container (not pictured). They seemed to print very well for the first 80%. However, once they reached close to the top of each container, the finish began to get messed up a bit.
Any input as to what causes this problem would be greatly appreciated.
without the print settings its hard to do more than paint out that PETG LOVES LOVES LOVES to pull moisture from the air and really needs to be dried before use and stored properly… .hell if you look at the desiccant some of it has already turned yellow which I take to mean has absorbed a lot of moisture …
Dry the PETG and give it another go… and send your print settings we may be able to diagnose better
Looks like a lack of cooling for me. In the middle, everything works fine because one layer takes enough time. Above the “ventilation hole pattern”, a layer can be printed so fast that the preceeding layer is still somewhat soft, so it gets torn away by the nozzle. When printing only 1 model, the layer time for these fast layers can be nearly the same, but the temperature in the printer might be lower when printing only 2h.
Quality-wise its best to increase the minimum layer time (filament settings under cooling, for generic petg it is 8s I believe), “slow down for better cooling” must be turned on. Try doubling this value to 12-15 seconds to see if it gets better. Beware: This increases print time.
Also helpful - more cooling:
leave door open
increase fans
less temperature for nozzle and bed.
Too much cooling reduces layer adhesion though, so don’t exaggerate.
Others report they get better results with the generic petg profile while printing with bambu basic petg - probably due to slower printing. You could give it a try.
Thanks for you thoughts… the desiccant I’m using is 10% Orange beads that turn dark when the desiccant is becoming saturated. The desiccant pictured is fresh. I didn’t dry the PETG though (noob). I just took it out of it sealed bag and put it in the AMS a week ago when I set up the system. In another post I’ve indicated that the AMS Hydrometer seems to be reveling positive signs as to the Humidity level in the AMS. Also the first print I made with this material turned out well.
Oh and my Bambu Basic PETG settings are as follows…
Wylie, thanks for posting your settings! Until now, I never really bothered looking at the settings for bambu basic petg to spot the difference to other petg settings, because I don’t have their petg. Now I did, and it’s obvious: The cooling fan starts at 10% when layers last 30s or longer and runs fastest with 40% when layers are only 8 seconds to complete:
I printed LOTS of petg with a fan starting at 40% and maxxing at 90%, with the same layer times of 30 and 8s. Try your print again with these setting, I bet you will succeed.
Don’t know why bambu sets values so low for their own petg - looks rather like ASA settings to me.
I will start a new topic about it the next days.
Yes, PETG absorbs some moisture from the air (its not the PET, its the G - the glycol), but its far less than many think.
You can store PETG without any problem at the air for weeks when your relative humidity is not like on a tropical island in the rain season. The absorption rate is very slow.
I have 2yrs old Extrudr PETG here, which is at the air since then. Can print this without any problem. Not only on the X1C, also in my CR10s-pro.
Exactly - 100% agreed. Wanted to write the same, but thought about making a new topic about it. In most topics where someone asks about a print problem, the first answers are always “Dry your filament”. This seams to be “en vogue” - I’m printing for 6 years now, and never had problems related to wet filament - only once with TPU.
The importance of drying depends on your environment. Here in central Ohio, the average year round humidity is 70%, but night time humidity is often 90+%. It’s currently sunny, but the humidity is 94%. I’ve learned the hard way that dry filament is a necessity for reliably good prints, so I record the weight of my spools before and after storing them in vacuum bags with desiccant. It is not unusual for a partial spool to gain 2-3 grams of moisture after a few weeks of storage. Think of taking even a single cube of water one centimeter on a side (one gram) and dumping it on a spool of filament.
Wylie’s problem probably is cooling, but for some of us, humidity and moisture will always be near the top of the troublemaker’s list.
thanks for your feedback! I thought about different climate conditions, but I’d guessed I am already in a rather humid part of the world. I live near Hamburg in northern germany, a place between 2 shores, known to be very rainy. Here is a table with longterm median of humidity. It’s in german, so i marked humidity row, columns are from January til december:
Yes, you would be familiar with high humidity. My moisture problems mostly caused stringing and flaws in surface finish. PETG is more resistant to moisture absorption than some other materials, but I still have to monitor it closely.
I just bought a filament dryer and tested it with a role of PETG. I know, that PETG absorbs moisture. But I never expected the difference it makes, even though I always keep the filament in the AMS or wrapped in foil with desiccant.
On the left side the PETG, how I had used it the last weeks. My prints of functional parts with this were okay. But now, after drying the result of the stringing test looks much much better. I’m very astonished!
If your petg is wet, the water comes to the surface as it passes through the surface in the form of steam and boiling water. The petg has a very tough time sticking to itself if water of anykind is on its surface. It is also emitting moisture in the nozzle and extruder so if its really absorbed moisture, you are steaming your filament as it enters the extruder!
Instead of a vacuum bag, try sealing it in one of those aluminum-mylar food preservation bags. That’s what people use to keep moisture out of emergency rations and keep their food preserved for 30 years at a stretch. Look for a minimum of 5mil aluminum coating on the mylar, but the thicker the better.
