<p>After encountering extreme under extrusion on my Anycubic i3 Mega, I first cleaned the nozzle and ended up replacing the entire hotend + nozzle. Since that did not help and I couldn't see any issues with it, I went on to check my E-steps. It seems that this is the root cause of the issue.</p>
<p>I removed the Bowden tube to have no resistance and used <code>G1 E100 F100</code> to feed 100 mm of filament through the extruder. The extruder only extruded ca. 23 mm though, so I had to adjust the E-Steps value from <strong>92</strong> to <strong>398</strong> which already seemed way off, seemingly &quot;fixed&quot; the issue though. When I repeated the test &quot;under load&quot; with the Bowden tube connected and the hotend heated to 220 °C (using PLA I normally print at 200 °C), the extruder once again only extruded a fraction of the supposed 100 mm (I don't remember the exact measurement, though approximately 30 mm). The gears seem to be fine, and the filament that is pushed against the small gear doesn't seem to slip either.</p>
<p>Unfortunately, that's where my experience ends, can someone tell me how to proceed to narrow down the issue? I suppose it could be the motor itself, a faulty stepper motor driver, loose cables, or the mainboard.</p>
<p><strong>Edit to @Citadel:</strong>
When I bought the printer it had a spare hot end that came with it. I simply replaced the old one with this one. I did not do any further hardware customization.</p>
<p><strong>Edit2:</strong>
Sorry for the late update, I wasn't able to check the printer before due to work. I swapped the stepper driver with one of the others on board and checked the e-steps again. Aaaand I just then I noticed I must have forgotten to save the to eeprom when I updated the e-steps last time... So of course I tried with the swapped stepper driver and original e-steps (<strong>92</strong>), but this didn't fix the issue. So the issue is not the driver. After that I changed the e-steps to <strong>398</strong> again and saved this time. Last time I accidentally started a print that that caused the eeprom reset before I saved the settings and tried the e-steps under load. This time it worked, even under load. I still believe this must mean that the motor is missing some steps but for now it seems to print fine. If I get issues again I'll next try to swap the motor. Thanks for your answers!</p>
<p>TL;DR: forgot to save the new e-steps due to starting a calibration print that reset the value before saving. New value actually works but probably indicates that something might be wrong with the motor as the stepper driver is fine.</p>

[{'answer_id': 20133, 'author': 'Stanley', 'author_id': 35678, 'author_profile': 'https://3dprinting.stackexchange.com/users/35678', 'pm_score': 2, 'selected': False, 'text': '<p>The raft still needs to fit on the bed, and it counts as a print, because, it is printed. You want the raft for better adhesion, so that means that you need more contact with the bed. If you’re not, your basically wasting filament. Its kinda logical actually.</p>\n'}, {'answer_id': 20136, 'author': 'Trish', 'author_id': 8884, 'author_profile': 'https://3dprinting.stackexchange.com/users/8884', 'pm_score': 1, 'selected': False, 'text': '<h2>Adjusted model Dimensions</h2>\n<p>The model has the size determined by the base area of the bounding box, in this case, <span class="math-container">$\\pu{190 \\times 200\xa0mm }$</span>. The raft as told by OP adds 15mm on <strong>all</strong> sides of the model, and thus adds 30\xa0mm in total on both the X and Y dimensions. This gets us a bounding box floor area of <span class="math-container">$\\pu{220 \\times 230\xa0mm}$</span>.</p>\n<p>The model\'s bounding box has a height of <span class="math-container">$\\pu{200\xa0mm}$</span>. Add to that the thickness of the raft. This is not mentioned, but in the worst case, this is about 3\xa0mm, and so you get <span class="math-container">$\\pu{203\xa0mm}$</span> as the maximum. Our model\'s Bounding Box thus is <span class="math-container">$\\pu{220\\times 230\\times 203 mm}$</span></p>\n<p>The smaller scale model (<span class="math-container">$\\pu{171 \\times 183 \\times 180 mm}$</span>) results in an adjusted area of <span class="math-container">$\\pu{201 \\times 213 \\times 183 mm}$</span>.</p>\n<h2>Printer dimensions</h2>\n<p>The standard Creality Ender3 v2 is set up with a build volume of (<span class="math-container">$\\pu{220\\times 220\\times 250 mm}$</span>) As your base area is 230\xa0mm in one dimension, it just can\'t fit. The slightly scaled item is <em>just</em> under that dimension and thus fits.</p>\n<h2>Solutions</h2>\n<p>With a firmware update, the printer can be told to use all of the bed, and then Cura\'s printer settings can be adjusted accordingly.</p>\n<p>Sometimes, but not in this case, rotating the model can result in a model that doesn\'t fit in normal orientation to fit: A line of 240\xa0mm doesn\'t fit along the X or Y axis, but easily along the diagonal of the printer. In fact, it is enough to turn the model by about 23.3° and the line fits:</p>\n<p><a href="https://i.stack.imgur.com/rP9Ab.png" rel="nofollow noreferrer" title="Graphic showing a 240 mm line at a 23.3-degree angle fitting inside a gray box"><img src="https://i.stack.imgur.com/rP9Ab.png" alt="Graphic showing a 240 mm line of 0.45 mm width first at horizontal orientation and then at a 23.3-degree angle fitting inside a gray box of 220 mm width" title="Graphic showing a 240 mm line at a 23.3-degree angle fitting inside a gray box" /></a></p>\n'}]
['https://3dprinting.stackexchange.com/questions/20185', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/36007/']