<p>I'm very new to 3D printing, but so far I've been able to print a couple things off Thingiverse without issue. However, as I'm trying to print another part, I've run into a situation where Cura is totally confused as to what's touching the buildplate and what isn't:</p>

<p><a href="https://i.stack.imgur.com/j56yL.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/j56yL.png" alt="enter image description here"></a></p>

<p>All I did was use the "mirror" feature to put it in a better orientation for printing....</p>

<p>Any ideas what's going on here? I'm using Cura 3.4 for Linux.</p>

<hr>

<p><strong>Update:</strong> I tried using the rotation tool instead as suggested by Oscar, but I get the same result:</p>

<p><a href="https://i.stack.imgur.com/4v0HG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4v0HG.png" alt="enter image description here"></a></p>

<p><strong>Update 2:</strong> Hmm so even when I just import the part without doing anything else, Cura is still confused:</p>

<p><a href="https://i.stack.imgur.com/jschr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/jschr.png" alt="enter image description here"></a></p>

[{'answer_id': 6491, 'author': '0scar', 'author_id': 5740, 'author_profile': 'https://3dprinting.stackexchange.com/users/5740', 'pm_score': 2, 'selected': False, 'text': '<p>If you want to mirror the print to get the top to the bottom, and visa versa, you just need to rotate the part using the XYZ rotation tool. Mirroring is used  to make a mirror image in the X-Z or Y-Z plane, not the X-Y plane. </p>\n\n<p>You might just caught a bug, you could post that of their forum.</p>\n\n<p>Update: </p>\n\n<p>If that does not fix it, you might have an incorrect STL model, e.g. the normals of the faces are incorrect. You could try to fix this by repairing the model through an online service like <a href="https://service.netfabb.com" rel="nofollow noreferrer">this one</a>.</p>\n'}, {'answer_id': 6492, 'author': 'OyaMist', 'author_id': 10938, 'author_profile': 'https://3dprinting.stackexchange.com/users/10938', 'pm_score': 2, 'selected': False, 'text': "<p>The up- or down-ness of a part is its Z-orientation, which is specified in STL. It looks like whoever published that STL file published it upside down, requiring you to flip the part or rotate it by 180. You can flip it in Cura as you've done or leave a comment to the author of the STL that the part is upside down.  However, the author may not know how to fix this because low-end modeling tools typically do not have the capability of flipping a model. In these cases, using another tool such as Cura or Slicer can generate a right-side up model. Cura seems to like generating AMF files, so I use Slicer to generate STL files for upside down models. Once you correct the STL file, you'll be able to import the model directly into Cura right-side up.</p>\n"}]
['https://3dprinting.stackexchange.com/questions/6489', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/12458/']