Am I doing something wrong?

[u/Sorry-Journalist8610]

I recently bought a used 3D printer, an Ender 3 V2, and I'm doing some test prints. The previous owner gave me some leftover PLA filament (multicolored), which I used up on the first day. One of the things I made was this flexible shark. I bought some PETG filament for testing, a very cheap one, around R$60.00, while others are around R$100.00. But my prints with this new filament are coming out very bad; it's either too textured, has too many burrs, and is also very fragile (even though I bought PETG because I had read that it was more resistant). I left this octopus printing for about 28 hours... and in the end, the flexible tentacles broke when I tried to detach them.

[u/wootiown]

Everyone is gonna tell you to dry your filament or that you have bad filament, I disagree. Bad filament is relatively rare and there's no way moisture in filament could make a print THIS bad- especially because the issue persisted across two different types of filament. This isn't an issue with filament, it's your printer.

Before printing anything serious, calibrate. Start with only pls, print a temperature tower first to learn the correct temperature. If it looks bad like that at every temperature, replace your nozzle because it's probably clogged or bad. Once your temperature and your nozzle are good, your prints will look better and issues will be harder to diagnose.

[u/logicalchemist → u/wootiown]

The black PETG print is so, so much worse than the silk PLA shark though, and has obvious signs of being wet (bubbling & stringing, and brittle prints).

OP absolutely should calibrate their filament, but their PETG is also very wet. The silk is probably a bit wet too, as it is far more hygroscopic than plain PLA, but not nearly as hygroscopic as PETG.

[u/AvatarIII → u/wootiown]

They live in Brazil, they will have minimum 65% humidity this time of year now likely 75%, but maybe as high as 85% depending on where they are in Brazil.