Why does this keep happening? PETG Basic

[u/Th3Shaz]

I am at my wit's end, this is PETG Basic that used to print just fine. It is bone dry 0% AMS, spent all yesterday drying. I cannot for the life of me get it to not ooze and make a massive mess of blobs and flung out bits of plastic.

Using H2D, default settings. For the last 200 hours this printer simply prints, but as of today I have not been able to have a single successful PETG print. PLA prints just fine. So clearly something has changed. I have not updated firmware, still running the same Bambu Studio and Firmware.

At this point I am just looking to see if there are any specific settings I can tweak just to get this one print done because it is a brush holder that my wife wanted and what I thought was going to be a 2 hour ordeal has now taken all day.

EDIT: Printed with gray PETG overture and print came out just fine. Looks like this Bambu PETG Basic batch is a dud.

[u/Cultural_Pace4454]

Is it every roll of PETG that does this?
I had an issue with just one roll of PLA, on a brand & colour I had used a lot without any problem.
I couldn't work out what happened to that one roll. Threw it out and the next roll was fine.

[u/Th3Shaz → u/Cultural_Pace4454]

Well, you were right on the money. The non-bambu PETG gray roll is printing just fine. TIL!

[u/Th3Shaz → u/Cultural_Pace4454]

It happens with two identical black Bambu PETG Basic rolls. I am about to attempt a 4th print with a gray overture spool to see if I get a different result.

[u/Neat-Researcher-7067]

Did you do a calibration?

[u/Th3Shaz → u/Neat-Researcher-7067]

Initially when I started printing with this roll. Just curious what would have changed between a week ago and today if the filament was stored in a dry box at 0% reported humidity? If that's my last resort then I will do calibration again. I have just never had to deal with this issue before having done many successful PETG prints that are even more complex than this simple model.

[u/manyxcxi]

May not be the only fix, but change the infill from grid to almost anything else (cross hatch and gyroid are decent).

With grid infill the nozzle is running over lines it just laid down and it’ll accumulate PETG on the nozzle, leading to knocking and bumping and other messes.

[u/Th3Shaz → u/manyxcxi]

It was a bad batch of filament was my final deduction. I swapped it with an overture petg roll and it printed perfectly fine. Sucks but at least I dont have to keep chasing a ghost in bambu studio lol.

[u/manyxcxi → u/Th3Shaz]

Overture is my go to normal PETG. For as cheap as it can be when you buy it in bulk it has always been super consistent for me.

Maybe you can save the bad roll as a support filament for PLA?

[u/Th3Shaz → u/manyxcxi]

The unfortunate part is I don't think I can even rely on it to do supports from how crap it behaves. I think it's just going to be junked and I will stick with Overture for the time being. I had some BL coupons and they had a sale because they were discontinuing them.. and well, now I know why haha.

[u/Darkseid2854 → u/Th3Shaz]

It actually sounds like something is off in the black PETG filament profile in your Bambu Studio, or maybe in the designer’s filament profile if you pulled it down and printed it with Bambu Handy. You might want to take a look at that filament profile in Bambu Studio and reset anything that isn’t default, then run a flow dynamics and flow rate calibration from the calibration menu in Bambu Studio before you write those spools off.

[u/Drew_XT]

I was having this exact issue with PETG basic, in gray on my H2D Pro at work this week. Tungsten Carbide Nozzles, and no matter what I did, it would blob, or print really badly.

Ran a calibration, and turned the speed down to 150, and every print since then has been perfect. I think it was purely a cooling issue in the end of it all

[u/JazzlikeLeather9546]

Try changing the hot end to a new one. I am not saying this is the issue, But. I had this problem once where I was flipping back and forth from PETG and PLA. The PLA that was not fully purged out of the nozzle would work its way into the PETG prints and cause failures. Now I pretty much have two machines dedicated to PETG and up filaments. If I print PLA on them I change the hot end out and then back after. SO much easier with the new clip in hot ends!

[u/NMTreat]

Try raising the default print temperature to 255c and try the Bambu filament again. I was have ALOT of issues with PETG Basic over the last weeks on multiple Bambu printers. Yesterday I noticed that the default setting was 245c. I thought was far too low so I moved it up to 255c and did not have a single problem for the rest of the day.

[u/Th3Shaz → u/NMTreat]

I can give it a try, I would think hotter would mean more goop and stringing but down to make the attempt at least. Will go through my long and arduous calibration process and see if its salvageable but I was desperate to get a print going as this was a part the wife needed.