<p>A couple of prints after leveling the bed (&lt;10), I noticed some weird sound, and saw the nozzle scratching the build-plate. 
What is really weird, is that I noticed (My printer is in quite a dark edge, so the build plate isn't really illuminated), that there were some scratches from a print before, but it worked fine with the prints in between.
So my question is, how that might have happened, could it be also software issues (Maybe some mistakes converting to gcode?), or is this propably purely a mechanical issue?
Furthermore, I'd like to ask whether this may cause any problems, e.g. massively reducing print quality, or weakening the grip of the prints.</p>

<p>I'm using the Tevo Michelangelo 3D, with manual leveling (it drives to the positions, but one has to tighten/loose the screws).
Note that <a href="https://3dprinting.stackexchange.com/questions/7332/tevo-michelangelo-nozzle-below-build-plate">I might have overtightened the screws in the beginning</a>. Another thing I noticed is that the screws on one side tend to be more loose than the other ones.</p>

<p><a href="https://i.stack.imgur.com/ROEST.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ROEST.jpg" alt="Build plate"></a></p>

[{'answer_id': 8029, 'author': 'HackerJ', 'author_id': 14286, 'author_profile': 'https://3dprinting.stackexchange.com/users/14286', 'pm_score': 0, 'selected': False, 'text': '<p>I currently have a couple scratches on the base of my Cr-10. They may have come, for me, from using tape on the bed as well as the nozzle being too close and rubbing. I have not noticed any quality difference during my prints. Noting Oscar, warping could also cause the nozzle to scrape the build plate when it goes over it. I am attempting to fix this problem on own printer.</p>\n'}, {'answer_id': 8031, 'author': '0scar', 'author_id': 5740, 'author_profile': 'https://3dprinting.stackexchange.com/users/5740', 'pm_score': 2, 'selected': True, 'text': '<p>As the question continued in comments, it can be read that the build plate had over-tight screws and loose screws on the build plate. This uneven tension could lead to stresses that warp the bed, e.g. lower corner and bulging out in the middle of the bed. When levelling on the corners, the nozzle could hit the bulge in the middle when printing. Furthermore, an endstop may have shifted during operation.</p>\n'}]
['https://3dprinting.stackexchange.com/questions/7645', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/12573/']