OK, so you’re new to 3D printing, but you’re not new to asking for help on the Internet. If you want people to be able to help, rule #1:

More. Pixels.

This might’ve been considered high quality for a digital image… in 1995. OK, maybe early 1995. Not by the end of the year. Find some more pixels. Don’t be stingy with them.

So next, for 3D printing it’s like asking for help with any tool - what kind of tool is it? Who made it? What model is it? Did you buy it new, or used? Does it have any modifications? Does it have an enclosure? What kind of work environment is it in? bedroom? garage? Is it a bed slinger? CoreXY? Delta?

What kind of software/firmware is the printer running? Which slicer are you using? Did you design the model yourself, or download it from somewhere? What software are you using for design?

And then what kind of material are you printing? PLA? PET? ASA? TPU?

Basically, we don’t know what you’re working with, or how you’re working with it, or what you’re trying to accomplish, and we can’t guess. There are hundreds of different printer models on the market, a few dozen different pieces of software that might be involved, and thousands of different print material options. Context, please.

On your issue - the most common problem with larger objects is that plastic tends to shrink as it cools. The longer the piece of extruded plastic is, the more effect the shrinkage has. As the top layer cools, it shrinks and pulls away from the layer below it. The larger the object is, the more time each layer has to cool before the next layer of hot plastic gets put on top of it. If your printer is open frame (not enclosed) this will be worse. If your printer is open and in a room with a draft, it will be even worse.

Resources:

• Stefan CNC Kitchen has published more video content of testing various aspects of hobby 3D printing than anyone else I know of.
• Michael Teaching Tech has a lot of specific advice for troubleshooting various issues, and some really interesting material on testing experimental new features. He has put together a fantastic resource for printer calibration teachingtechyt.github.io/calibration.html If you want to really learn about how your printer operates, go through that step-by-step guide.

And finally, the pixels… don’t forget the pixels.