<p>As stated above, I am trying to solve a problem I've had for a long time. Unfortunately, this has recently intensified to the point where it causes layer splitting/detaching from each other. I have tried various ways to fix this and, while decreasing the temperature and extrusion multiplier improved the situation, the problem is still present. </p>

<p>My settings:
<li>Nozzle 235&nbsp;&deg;C Bed 100&nbsp;&deg;C
<li>Cooling 25&nbsp;%
<li>Extrusion multiplier 0.89
<li>Speed 150&nbsp;mm/s for everything, 50&nbsp;mm/s for small perimiters
<li>Acceleration 1000&nbsp;mm/s<sup>2</sup>, (default) 
<li>Layer height 0.15-0.3mm
<li>Line width - 0.6mm for everything, but 0.45 for first layer and 0.42 for top solid infill</p>

<p>Is there a different solution than lowering print speed or buying an E3D silicon sock? I have lost my spare ones and the current one wore down. Obviously, I can simply pause the print when I see plastic bulding up on the nozzle, but I am sure that there is a more efficient solution.</p>

<p>UPDATE: I found that the hotend was very dirty and full of burnt/molten plastic. I am almost sure that the hotend is leaking somewhere between the heat block and the heat break. This didn't happen before I replaced the nozzle. How can I fix this? Do I have to replace the heat break or some other part?</p>

[{'answer_id': 13743, 'author': 'FarO', 'author_id': 2338, 'author_profile': 'https://3dprinting.stackexchange.com/users/2338', 'pm_score': 2, 'selected': False, 'text': '<p>I saw PETG printed at 100 mm/s, but 150! That\'s a lot.</p>\n\n<p>One solution to avoid blobs may be to limit the maximum speed to a value you can actually achieve with reliable results.</p>\n\n<p>Simple test to find your machine limits (each combination filament brand + nozzle + temperature has a different value): extrude filament in the air at increasing speeds, see how the flow changes, and when you see more than 5% decrease, that\'s it.</p>\n\n<ol>\n<li>M83</li>\n<li>mark the filament as if you were calibrating the E steps</li>\n<li>calculate filament speed: speed = volum/s / filament surface * 60 = mm^3/s * 25 (this factor is valid for 1.75 mm filament)</li>\n<li>set extrusion speed for 2 mm^3/s: G1 F50</li>\n<li>extrude 50 mm: G1 E50</li>\n<li>measure actual length extruded</li>\n<li>repeat 2.-6. but increase the speed by 2 mm^3/s each time: 2, 4, 6, 8, 10, 12, ...</li>\n<li>at a certain speed you will see that the actual filament length starts to decrease. When you see that the underextrusion reaches 5-10% (depending how much underextrusion you accept), write down that volumetric speed (mm^3/s) somewhere, it\'s your limit for THAT filament + THAT nozzle + THAT temperature</li>\n<li>Either a) calculate the max print speed = volumetric speed / layer height / line width or b) set the maximum volumetric flow rate in the slicing software so that the speed will be automatically capped taking into account layer height and line width. <a href="https://help.prusa3d.com/en/article/max-volumetric-speed_127176/" rel="nofollow noreferrer">Prusaslicer</a> allows to set that in the "Print" or in "Filament" settings, I recommend it for "Filament" settings, since it\'s a filament-dependent parameter.</li>\n</ol>\n\n<p>Example data from <a href="https://www.cnckitchen.com/blog/flow-rate-benchmarking-of-a-hotend" rel="nofollow noreferrer">CNC Kitchen</a>:</p>\n\n<p><a href="https://i.stack.imgur.com/xXRYV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xXRYV.png" alt="enter image description here"></a></p>\n\n<p>You can increase the max print speed, at the price of a little loss of quality around edges, if you calibrate the E steps at a speed corresponding to 2-3% underextrusion (alternative: to the speed of outer perimeters).</p>\n\n<p>This way you know that when you print slower than that (uncommon... typically only sharp corners and small perimeters) you\'ll get up to 2-3% overextrusion, and you extend by 2-3% the maximum print speed, since your max speed is the one where you get 5-10% underextrusion compared to your E steps calibration speed.</p>\n'}, {'answer_id': 13791, 'author': 'R.. GitHub STOP HELPING ICE', 'author_id': 11157, 'author_profile': 'https://3dprinting.stackexchange.com/users/11157', 'pm_score': 1, 'selected': False, 'text': "<p>Even not extruding anything but just performing travel moves over PETG at 100 mm/s or higher will <em>tear it up and drag material all over the place</em>. The result is blobs stuck to the nozzle, possibly even stringing, and choppy lines that the next layer will not properly adhere to. PETG simply cannot be printed at these kind of speeds regardless of how fast your hotend can melt it.</p>\n\n<p>Turn <strong>all</strong> speeds, print and travel, down to 40-50 mm/s, then experiment to see if you can increase them at all.</p>\n\n<p>Note that if your acceleration is only 1000 mm/s², you're basically never going to reach the desired 150 mm/s anyway, so this probably won't be as much of a slowdown as you expect. Jack the acceleration up as high as your machine can handle and it might still print as fast or faster, but without the blobs.</p>\n"}]
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