When one of my prints finished yesterday I found this small screw on my buildplate and I just cant see where it belongs. The printer still works fine so I´m wondering if it comes from somewhere else. Can someone tell where it belongs? 
Hello @mwt1976 …! 
Welcome to the Creality Forum…! 
Look underneath the nozzle and extruder assembly.
Videos such as these 
might help you find which bolt is missing.
It certainly looks like a screw from the extruder assembly. In the few months that I’ve been 3D printing I’ve learned the hard way to check ALL screws, nuts, bolts etc. Just because they’re assembled at the factory doesn’t always mean they have been tightened properly!
2 Likes
This kind of problem also happened to my printer before, but later I learned to manually tighten the visible screws when updating the hardware 