<p>After noticing that my ender 3 couldn't print a 'perfect' circle I decided to use a <a href="https://www.thingiverse.com/thing:1278865" rel="nofollow noreferrer">calibration cube</a> to see if that could be the issue. These were my results:</p>
<p><a href="https://i.stack.imgur.com/OHJOF.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/OHJOF.jpg" alt="X Y Z" /></a></p>
<p>I did have some successful prints before noticing these problems but it would be great if anyone could help/find a solution.</p>
<p>I think it may be because of the belts tension as I had accidentally over stretched it by putting it over the wheels instead of under: is it worth getting a new belt then?</p>
<p>I use 20% infill, with triangle pattern in cura, using the standard 0.4mm nozzle.</p>
<h1>Edit</h1>
<p>After doing a <a href="https://www.thingiverse.com/thing:3090144" rel="nofollow noreferrer">different testprint</a> and measuring, it revealed that both had an accurate 20mm Y and Z, but only an 18.5mm X. Might I have destroyed my belt when I mounted it overstrained?</p>
<h1>Edit2:</h1>
<p>After purchasing a new X belt, the calibration cube was much closer at 19 x 20 x 20. But still not at a good enough tolerance for my liking. Additionally, when printing a cylinder, two relatively flat edges were printed with it either side (perpendicular to the x-axis).</p>

[{'answer_id': 6870, 'author': 'Trish', 'author_id': 8884, 'author_profile': 'https://3dprinting.stackexchange.com/users/8884', 'pm_score': 3, 'selected': True, 'text': '<p>Your top layer looks like you need to add additional top layers and there are signs of a slight bit of over-extrusion in that top layer (red). On the other hand, it looks like the top layer is not sliced nicely resulting in gaps and holes (yellow), which might be a fault of the test print.</p>\n<p><a href="https://i.stack.imgur.com/pJooa.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pJooa.jpg" alt="Z, defects marked" /></a></p>\n<p>The X on the file you used is not centered, resulting in the off look in the print.</p>\n<p>I suggest you try a different calibration print before starting to tinker with the hardware, for example <a href="https://www.thingiverse.com/thing:3090144" rel="nofollow noreferrer">this</a>.</p>\n<p>I suggest to use concentric only for the top layers and instead rely on a simple Zig-Zag pattern for the intermediate layers, as this usually generates a better connection to straight walls.</p>\n<h1>EDIT1:</h1>\n<p>After considering the miss-dimension in X only, you might want to look to <a href="https://3dprinting.stackexchange.com/questions/3344/calibrating-steps-order">calibrate your X steps</a>.</p>\n<p>The stretching of the belt might be an issue, but you might get away <em>easy</em> if you just check belt tension and manage to get it right again.</p>\n<p>As I have an ender-3 myself, I know you might need to <a href="https://3dprinting.stackexchange.com/questions/6399/recalibrating-home-position">flash</a> <a href="https://3dprinting.stackexchange.com/questions/6657/export-firmware-as-a-hex?noredirect=1&amp;lq=1">fresh</a> firmware to get the ability to change the steps/mm.</p>\n<h1>EDIT2:</h1>\n<p>The 19x20x20mm cube sounds like the new belt did fix a lot of the dimensioning problem, but the steps/mm might be slightly off - or we have to trace down SOME mechanical error in the movement path. As a 140mm long test print also had a 1mm offset, a steps/mm error should be out.</p>\n<p>After examining the machine with jb <a href="https://chat.stackexchange.com/rooms/83007/ender-3-calibration-cube-fail">in chat</a>, the bearing on the X-belt seemed to stick a tiny bit on one side.</p>\n<p><a href="https://i.stack.imgur.com/qTjdg.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qTjdg.jpg" alt="Ender3 X-tightener/bearing" /></a></p>\n<p>Turning the large bolt of the assembly in an attempt to disassemble it without a wrench to hold the self-securing nut on the far side seemed enough to lessen the pressure on the core of the bearing, allowing it to spin freely. In addition, the belt was a little loose.</p>\n'}, {'answer_id': 6873, 'author': 'Sean Houlihane', 'author_id': 4927, 'author_profile': 'https://3dprinting.stackexchange.com/users/4927', 'pm_score': 2, 'selected': False, 'text': '<p>First, check that the calibration part you have is actually a cube. Maybe you downloaded a trick \'calibration cube\' model. Cura will show he overall dimensions of any model which it is slicing.</p>\n\n<p>Ignore any print quality issues first off. A hollow calibration cube is mainly used to check the X/Y/Z motion and so long as you print at a sensible (slow) speed), the other parameters shouldn\'t have much effect (so long as the first layer is OK, and you get within 30% of the right extrusion).</p>\n\n<p>If the calibration cube is within +/- 0.5mm on each side, it\'s probably good. Under/over extrusion, caliper technique, etc, can explain this sort of variation, and you might want to use a bigger test part like <a href="https://www.thingiverse.com/thing:2566871" rel="nofollow noreferrer">this star on my thingiverse account</a> once you think you\'re close.</p>\n\n<p>The \'steps per mm\' setting is determined within the firmware, it is part of how your printer consumes G-code. For a delta printer, for example, there is some fancy maths to combine X/Y/Z into the motor movements. This means that you can\'t change steps/mm in Cura, you need to either change the firmware defaults and \'reset to factory settings\', or modify the parameters in EEPROM by sending G-code.</p>\n\n<p>Seeing too small a calibration part (for a Cartesian printer) can easily be explained by problems in the printer\'s motion system:</p>\n\n<ul>\n<li>Stepper missing steps due to jerk or acceleration too high</li>\n<li>Stepper missing steps due to binding/friction in the bearings (Send <code>M84</code> to idle the stepper motor, and move X by hand)</li>\n<li>Teeth missing on the drive belt (may show up on a diagonal \'bar\' print)</li>\n<li>Loose drive pinion (maybe backlash on the flat on the spindle means the problem is greater on small parts) - see below</li>\n<li>Flex in the drive mechanism (e.g. belt mount to traveller is loose)</li>\n</ul>\n\n<p>An annoying feature of a lot of these problems is that for any particular repetitive sequence of steps, you might see a very consistent result. Even thought to problem is something being badly adjusted, it gives the impression that the problem is calibration.</p>\n\n<p>The drive wheel is held in place with a grub screw, see this diagram from the Anet-A8 assembly diagram.</p>\n\n<p><a href="https://i.stack.imgur.com/1C3fcb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1C3fcb.png" alt="Anet X-drive"></a></p>\n'}]
['https://3dprinting.stackexchange.com/questions/6869', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/12820/']