<p>I have problems with layer widths and uneven outer walls on my 3D prints. Sometimes layers are squeezed and sometimes pushed outside. I noticed that these problems happen when there are retractions on layers. I don't have problems with round and simple objects without changes on layers or where all layers are identical.</p>
<p><a href="https://i.stack.imgur.com/wgANn.jpg" rel="nofollow noreferrer" title="Image showing uneven layers"><img src="https://i.stack.imgur.com/wgANn.jpg" alt="Image showing uneven layers" title="Image showing uneven layers" /></a></p>
<p>I think that this can be linked with pressure in the nozzle or retraction. It looks like sometimes the pressure is too high and it's pushing too much filament and sometimes it's too low and it's not pushing enough filament. In this picture, layers in the first circle are squished in and it looks like there is not enough filament being pushed from the nozzle. In the second circle layer is pushed out and is wider than other layers. Looks like there is not enough filament being extruded at the start of the layer and too much being extruded at the end.</p>
<p><a href="https://i.stack.imgur.com/eTbfq.jpg" rel="nofollow noreferrer" title="Image showing two areas: one with layer pushed in, and one with layer pushed out"><img src="https://i.stack.imgur.com/eTbfq.jpg" alt="Image showing two areas: one with layer pushed in, and one with layer pushed out" title="Image showing two areas: one with layer pushed in, and one with layer pushed out" /></a></p>
<p>This problem happens always on the same layers, where there are some retractions on these layers. I tried to print the same objects multiple times and it always occurs on the same layers.</p>
<p><a href="https://i.stack.imgur.com/UIP6a.jpg" rel="nofollow noreferrer" title="Image showing squished in layers"><img src="https://i.stack.imgur.com/UIP6a.jpg" alt="Image showing squished in layers" title="Image showing squished in layers" /></a></p>
<p><a href="https://i.stack.imgur.com/GyHLJ.jpg" rel="nofollow noreferrer" title="Image showing squished out layers"><img src="https://i.stack.imgur.com/GyHLJ.jpg" alt="Image showing squished out layers" title="Image showing squished out layers" /></a></p>
<p>What have I did to fix this problem:</p>
<ul>
<li>calibrated e-steps and slicer flow,</li>
<li>tightened belts,</li>
<li>different slicers (Cura, PrusaSlicer),</li>
<li>different filaments (e.g. PrusamentPLA),</li>
<li>disabled combing in slicer,</li>
<li>printed with and without infills,</li>
<li>different retraction distance (from 3 mm to 8 mm),</li>
<li>different retraction speeds (from 20 mm/s to 80 mm/s),</li>
<li>different retraction accelerations (from 500 to 1500),</li>
<li>different hotend temperatures (from 200 °C to 230 °C),</li>
<li>slow printing speed (up to 15 mm/s),</li>
<li>calibrated K-factor (also tried many values from 0.0 to 2.0),</li>
<li>calibrated junction deviation (also tried many values from 0.0 to 0.3),</li>
<li>printed with and without cooling.</li>
</ul>
<p>I think, that disabling coasting and changes in retraction settings helped a little, but not too much.</p>
<p>My setup:</p>
<ul>
<li>Ender 5, SKR mini E3 V1.2</li>
<li>Capricorn PTFE Bowden tube,</li>
<li>printing with PLA, but this problem also occurs with PETG.</li>
</ul>
<p>The most similar issue I've found is this question, <a href="https://3dprinting.stackexchange.com/q/10738/4762">Inconsistent Layer Issues</a>, but this didn't resolve my problem.</p>
<p><strong>How can I get rid of inconsistency in layers widths and get smoother outer walls?</strong></p>
<hr>
<p>I calibrated K-factor with <a href="https://marlinfw.org/tools/lin_advance/k-factor.html" rel="nofollow noreferrer">K-factor Calibration Pattern</a> and discovered that lines are always thicker after retraction at the start of the line and thinner at the end of the line. Then I generated and printed test files to confirm this. My lines are always thicker at the start of the line and they get thinner later. This is the problem presented in the second picture.</p>
<p>I printed 3 cubes (dimensions of a cube: X=0.2 mm, Y=100 mm, Z=10 mm). This is the result.</p>
<p><a href="https://i.stack.imgur.com/UFWb8.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UFWb8.jpg" alt="Result of printing 3 cubes (X:0.2 mm, Y:100 mm, Z:10 mm)" /></a></p>
<p>This is the best representation of my problem. The order of printing was as follows: 1 -&gt; 2 -&gt; 3 -&gt; 4 -&gt; 5 -&gt; 6 -&gt; 1 -&gt; 2 etc. There are under extrusions at the end of the second and third line (points 4 and 6) and under extrusion at the start of the first line (point 1). These under extrusions are before (points 4 and 6) and after (point 1) travel moves.</p>
<p><strong>What can cause this problem?</strong></p>

[{'answer_id': 18367, 'author': 'TreeBarkEater', 'author_id': 28896, 'author_profile': 'https://3dprinting.stackexchange.com/users/28896', 'pm_score': 2, 'selected': False, 'text': '<p>You can do this provided the part releases consistently after cooling. Your filament choice may cause problems, though. ABS is prone to warping and a fan constantly blowing on the part would make it worse. The second thing to consider would be the release agent. I assume you are using gluestick or something similar on the bed. This may be pulled off the bed after a couple prints.</p>\n'}, {'answer_id': 18370, 'author': 'Criggie', 'author_id': 12956, 'author_profile': 'https://3dprinting.stackexchange.com/users/12956', 'pm_score': 0, 'selected': False, 'text': '<p>In theory you could knock the item off the build plate and into a bin by positioning the print head behind the part and then pushing.</p>\n<p>However your build plate would need to have a smooth front edge, so no clips in the way.</p>\n<p>You\'d also want to have some delay to let the bed cool down before attempting this, and have spare belts on hand for the day the installed belt breaks.</p>\n<p>A fan may work IF you can control it to come on after the part has finished printing, AND your printer will release a finished part given time.  Also, your finished part must be strong enough to survive the impact and fall without damage, else what\'s the point?</p>\n<p>Also, your effective print volume would shrink - there has to be enough space at the back to drop the print head behind the part using gcode, and then slide the bed backward until the part falls off.  You couldn\'t use the back ~75mm of the bed.</p>\n<p>Personally I always have to use a scraper and occasionally a light hammer tap, so a fan wouldn\'t do anything.</p>\n<hr />\n<p>If I were doing this, I\'d either pony up and buy one of those Creality belt-fed printers that have a rolling platform, and drop parts off the front.  The CR-30 <a href="https://www.creality3dofficial.com/products/cr-30-infinite-z-belt-3d-printer" rel="nofollow noreferrer">https://www.creality3dofficial.com/products/cr-30-infinite-z-belt-3d-printer</a> or other manufacturers would have the same.</p>\n<p>The other more homebrew option would be to consider where the bed ends up after job is done, and then have some kind of &quot;wiper&quot; mechanism that comes from the side and pushes the part over and off the bed.  It would have to be low enough to get any brim and priming lines out of the way too.  Since the printer probably can\'t control this, you\'d be looking at an external controller like a computer running a print server, orchestrating the wiper and then starting the next job.</p>\n<p>You\'ll also want a really big roll of filament, or a filament-out sensor so you\'re not printing air.</p>\n'}]
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