A number of things - the Z axis seems loose, the other axes skip steps (possibly the stepper drivers overheating), general issues with bed adhesion and warping.
All common 3d printer issues, though some are exacerbated because I bought a cheap kit from an unknown supplier. I got to a point where every time I fixed I problem I'd notice two other ones, and put it down and haven't picked it back up.
Good advice for people getting 3d printers is to decide if you want a printer as a tool for design/prototyping, or 3d printing as a hobby. I told myself I wanted the second as a path to the first, but after many hours of printer building I concluded that I really just wanted the first.
All common 3d printer issues, though some are exacerbated because I bought a cheap kit from an unknown supplier. I got to a point where every time I fixed I problem I'd notice two other ones, and put it down and haven't picked it back up.
Good advice for people getting 3d printers is to decide if you want a printer as a tool for design/prototyping, or 3d printing as a hobby. I told myself I wanted the second as a path to the first, but after many hours of printer building I concluded that I really just wanted the first.