Bad print using PETG

Got an X1C and love it. I started to use Bambu Basic PETG Black (New). Its been in the AMS for a few days and reads 10% humidity. I have been most printing with PLA and had perfect looking models. Someone told me I should try PETG so here we are. Standard .20 default setting using a .4 nozzle. Printing on a Bambu textured PEI Plate. Some of the print looks great, but what the heck is going on for the right corner. Can’t be wet filament, could it be nozzle heat. Like mentioned the printer bed, nozzle and speed are all standard based on the Bambu filament. Note that I created a user preset for this filament to keep the AUX fan from coming on to avoid warping (seen this a lot with PLA). If this continues Im going to go back to printing with PLA. Note that the house temp stay around 72 degrees and I print with the door closed and top on.

how does the build plate side print look oposite to that corner?
I kind of have the feeling that this corner detached of the build plate and caused that section to bend up a bit.

Here is a top and bottom pic of the print as it relates to the plate. I always clean my plate with rubbing alcohol before prints so I know it was clean. I do remember seeing on first layer similar rough lines but didn’t think nothing about it as it was covered up by a few additional layers that looked clean.

Yeah looks like it lifted off the build plate at the corner.
Rubbing alcohol still can leave some residue and just smear it around on the build plate surface. A thorough scrub with a good dishwashing detergent, afterward rinsing and drying is a better method for cleaning the build plate.
The first layer quality is one of the most important things on a print, problems there can ruin the whole print at a later stage, stop the print if you see problems happening there.

Thanks. I’ve always use rubbing alcohol, but I’m going to wash The plate with detergent and try re-printing to see if that does it.

Take a look at this first layer… Looks like I can see though it in certain places…Why… Cleaned plate and even tried a High Temp Plate but still same issue… Could the filament be wet even though the AMS shows 10% humidity. I just tried PLA and it looks like ■■■■ as well now…Hum. The other day I had a blob form around the extruder nozzle. I cleaned it but this is the first print after that. I wonder if the nozzle get screwed. Only one way to find out…Replacing it now with a .4 and going to try PETG again… Fingers crossed.

Well that wasn’t it…Now running built-in calibration test. Something is off for sure.

Maybe a partial nozzle clog?
Do you have bed levelling enabled?

Ah, which speed are you printing at? I did extensive tests with several brands and BambuLab PETG is really no good above 120mm/s. In my experience, it is really low quality in many respects. It tends to do tiny curls which leave holes in walls, layer adhesion is mediocre at slower speeds and terrible at higher speeds (e.g. 300mm/s), it doesn’t print overhangs very well, doesn’t release from build plate well. After comparing to other brands, I will sell my still sealed rolls.

Yet, all that doesn’t explain the voids in the first layer.

Just sharing my experiences:

  1. a factory reset following firmware updates seems to be mandatory. sudden issues disappeared. in my head this is a golden rule.

  2. when I first printed with PETG I ran into almost the exact same issues. 99% cleaning alcohol helps a lot on the textured PEI plate, the tiniest finger print causes big troubles.

  3. if you got a spare: swap your nozzle. In my case it was missing a tiny amount of thermal paste (air bubble). never had a clogged one, but I’d double check.

  4. as result of my continuous fails printing PETG I created a print profile for Bambu Lab PETG transparent. use this as starting point to narrow down the root causes for your situation

you can find the profile being assigned to this model LED Lamp 001 by Bambu Lab - MakerWorld, named [PETG Transparent] - Type B ~Milosh Keat.

Keep us posted and best of luck :muscle:

Yes. And new nozzle. Could the filament be damp even thought it shows 10% in AMS.

I have had nothing but problems printing Bambu Lab PETG. I have 2 rolls of PETG from Bambu (grey and black) that seem to be hit and miss in their quality of prints, the black being the worst. Consistent issues on first layers, layer adhesion issues, stringing and popping all over the place. Thought it might be clogging, nope, nozzle and gears all clear. Thought it might be the AMS slot, tried a different manufacturer PETG in same slot, prints beautifully no issues. Tried printing off the back spool no AMS, same problem. I have switched the Bambu Lab PETG settings to Generic PETG in the slicer, same problem. Tried slowing down the print speed, works marginally better, but still garbage. I have tried filament drying it, nada, humidity in the AMS/spool box also less than 10%, no difference. Other PETG from other brands print like silk, no issues. Bambu PETG, prints like garbage. Made the mistake of buying 2 more rolls during a sale before I started using the first 2. Now I have 4 rolls of PETG paperweight.

Im going back to PLA and will just print things a second time if they fall apart. BTW, what PETG brand did you have good luck out of. I might try a roll of that. The bad news is everyone is going to cardboard spools and I hate that. fining a cardboard spool ring that fits right and still fits the AMS with the lid closed has been challenging. Respelling seems to be a pain in the tail but might be my only option.

Up to now, I have compared 5 brands printing and destroying almost 1kg or more than 140 samples.

I had very good results with Sunlu which is super cheap. Prints very nice at 300 mm/s with good overhangs and very good layer adhesion. Releases very easy when cooled. I’m using 20% part fan and 20% aux fan. If you want slightly better layer adhesion, reduce speed to 100-150 mm/s, but it is better at 300 than most others at 120.

One even better brand was german manufacturer, but they were close.

I still want to test polymaker and eSun, but I don’t expect surprises.

Very interested in this topic as I print almost 100% in PETG on my X1C. I’ve had the printer about a month now and ran roughly 10kg of PETG through it in that time. Here are some observations I’ve noticed in that time:

As others have stated, build plate cleanliness is important. Dawn dish soap and warm water then dry it off and you’ll be set. Isopropyl works in a pinch but should not be the only cleaning method. I’ve tried Clorox house wipes and they did not work very well - I believe they left cleaning solution residue on the build plate.

I’ve had good success with Bambu brand PETG, but perhaps we all have different levels of acceptance. I feel like I’m on the low end of what I deem “acceptable” compared to others. I have had some consistency issues with the PETG material which I assumed to be a dirty build plate, dirty nozzle, etc. I have never dried it out properly which could contribute to the consistency issues.

One immediate improvement for my PETG prints was slowing down several settings and decreasing the first layer width. I’m happy to share my settings if anyone is interested (I’m at work otherwise I would post a screenshot).

If there is an issue with print quality, in my experience, I believe it has been one of two typical issues. Either layer 1 adhesion problems or excessive filament built up on the nozzle which is interacting with the print process in a number of ways. The solution for each of these issues is generally pretty straight forward and well documented online. I’m still trying to figure out why the second issue occurs, and ultimately how to prevent it. If there is any insight on preventing excess filament build up on the nozzle during the printing process, I’d love to hear it!

I have tried SUNLU brand PETG in small amounts, but not enough to make an observation on. It comes highly recommended and I’d love to see how it stacks up against the Bambu brand stuff. If it prints better than the Bambu brand, I’m happy to switch.

I’ll finish this thread hijacking with a question; has anyone tried Prusament brand PETG? From what I’ve read online their stuff is top tier quality.

I’ll be following this thread to see what insight anyone else has! Thanks everyone for all the great info and happy printing! :grinning:

I’ve had similar defects due to a plate that had had its day. Try to move the model away from that area and see if the defect moves too. If it disappears, you may need to replace the plate or avoid that area with flat sections. If it stays I’m leaning towards calibration of filament/dryness.

PETG is more sensitive to humidity than PLA and a new spool right out of a vacuum pack with desiccant does NOT warrant dry filament at all. You should use a dedicated dryer, a food dehydrator or dry it on the printer’s heatbed. Do not try your kitchen oven, it will likely ruin the filament.

Definitely. The fact that the AMS or any other storage is at 10% RH means it can keep filament dry - but it will not make it dry. Not even in months. You can dry wood that way, but not filament.


Same. Fantastic results with Sunlu using the generic petg profile. Cheaper than BBL and usually available with Amazon Prime shipping. I have maybe 10 different colors of BBL PETG, and with varying amounts of success they generally suck. I have had better luck running them under the generic profile, but it sure seems like Bambu did not put in the effort that they did tuning their PLA formulas and profiles.

I have great results with Elegoo Rapid PETG, but except for black, amazon doesn’t seem to have any more stock in colours. I had picked up a 4-pack with different colours and that PETG is near bulletproof. No issues with stock slicer settings and prints like a dream even after being left in the AMS with desiccant for weeks. Trying to find more of it as my stock dwindles but no luck. Sunlu I found was so-so, but much better than Bambu, however it needs to be dried out after being open a while even in dry box or AMS with desiccant.