<p>This has happened a few times whenever I print with the white PLA (Hatchbox 1.75 mm). It seems that the print job produces smooth sidewalls for most of the part but at a certain point and above, the walls become rough as if the alignment is off or something. I've attached a picture to show the issue. Does anybody have any insight?</p>

<p><a href="https://i.stack.imgur.com/796O7.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/796O7.jpg" alt="Problem demonstration"></a></p>

<p>I'm using a Printrbot Simple Metal and some of the print settings are listed below:</p>

<ul>
<li>Slicer: Slic3r</li>
<li>[First] Layer height: 0.2 mm</li>
<li>Perimeters: 2</li>
<li>Solid Layers [top/bottom]: 3</li>
<li>Infill: 25%</li>
<li>Fill pattern: Rectilinear</li>
<li>Top/Bottom Fill pattern: Concentric</li>
<li>Perimeter speed: 30 mm/s</li>
<li>Infill speed: 80 mm/s</li>
<li>Travel speed: 150 mm/s</li>
<li>Acceleration (perimeters): 1000 mm/s<sup>2</sup></li>
<li>Acceleration (default): 3000mm/s<sup>2</sup></li>
<li>Default extrusion width: Slic3r chosen</li>
<li>Print temperature: 220°C</li>
</ul>

<p>I've noticed in the Slic3r rendering that the affected area seems to be the point where the infill switches from 25% to solid as seen in the included picture. If this is the problem, is there any way to enforce solid infill a few layers below this to eliminate the awkward transition, or specify a smaller extrusion width at this point?</p>

<p><a href="https://i.stack.imgur.com/DfWDP.png" rel="noreferrer"><img src="https://i.stack.imgur.com/DfWDP.png" alt="Screenshot of infill switch"></a></p>

[{'answer_id': 3618, 'author': 'ItamarG3', 'author_id': 6090, 'author_profile': 'https://3dprinting.stackexchange.com/users/6090', 'pm_score': 2, 'selected': False, 'text': '<p>Slic3r has an option of</p>\n\n<pre><code>Solid infill threshold area \n</code></pre>\n\n<p>which is the area that when you pass it (and start printing smaller than it), the infill becomes solid.</p>\n\n<p>If you set it to a smaller number (or 0), then your infill won\'t become solid and the problem will vanish.</p>\n\n<p>Source: <a href="http://manual.slic3r.org/expert-mode/infill-optimization" rel="nofollow noreferrer" title="slic3r manual">Slic3r Manual - Infill Optimization</a> </p>\n'}, {'answer_id': 3625, 'author': 'lz42', 'author_id': 6107, 'author_profile': 'https://3dprinting.stackexchange.com/users/6107', 'pm_score': 4, 'selected': True, 'text': '<p>If you want to change settings on some area of your part check out <a href="http://slic3r.org/blog/modifier-meshes" rel="nofollow noreferrer">modifier meshes in Slic3r</a>.</p>\n\n<p>It looks like to0 much heat is delivered when solid infill starts and some melting occurs. See <a href="https://all3dp.com/common-3d-printing-problems-3d-printer-troubleshooting-guide/#Extrusion-Temperature" rel="nofollow noreferrer">3D Printing Problems #22: Extrusion Temperature Too High</a>. </p>\n\n<p>You can try:</p>\n\n<ul>\n<li>Lower extrusion temperature</li>\n<li>Lower filament flow</li>\n<li>Improve part cooling</li>\n<li>Lower print speed</li>\n</ul>\n'}]
['https://3dprinting.stackexchange.com/questions/3617', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/5938/']