Ender 3 Calibration Cube Fail + Can't Print Circles

  • After noticing that my ender 3 couldn't print a 'perfect' circle I decided to use a calibration cube to see if that could be the issue. These were my results:

    X Y Z

    I did have some successful prints before noticing these problems but it would be great if anyone could help/find a solution.

    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?

    I use 20% infill, with triangle pattern in cura, using the standard 0.4mm nozzle.


    After doing a different testprint 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?


    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).

    what are your slicer's settings for "number of top layers"?

    @Trish I used Cura, would Slicer be better? For cura my top/bottom thickness is 0.6 mm; (the layer was 0.1 mm); the top thickness was 0.6 mm and top layers was 6

    cura is perfectly fine. Any infill? what's the nozzle diameter?

    @Trish 20% triangle infill. I don't know about the nozzle diameter: default for ender 3 1.75mm

    Mind updating photos of the new print? the 18.5 for 20 seems consistent as you said in chat.

    @jb7852 - I think the 1.75mm is the filament diameter ... it should be stamped directly on your nozzle what size it is. I'd suggest it's probably 0.4mm.

    This looks like missing steps or binding in x direction. Does the carriage run smooth with depowered steppers (M84)?

    My prints look almost erily identical on the cube test and i am getting bad circles. what was the best solution? did you ever fix it?

  • Trish

    Trish Correct answer

    4 years ago

    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.

    Z, defects marked

    The X on the file you used is not centered, resulting in the off look in the print.

    I suggest you try a different calibration print before starting to tinker with the hardware, for example this.

    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.


    After considering the miss-dimension in X only, you might want to look to calibrate your X steps.

    The stretching of the belt might be an issue, but you might get away easy if you just check belt tension and manage to get it right again.

    As I have an ender-3 myself, I know you might need to flash fresh firmware to get the ability to change the steps/mm.


    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.

    After examining the machine with jb in chat, the bearing on the X-belt seemed to stick a tiny bit on one side.

    Ender3 X-tightener/bearing

    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.

    I 100% agree. Do you have any idea why my main issue was occurring i.e. the X wasn't centered/how squares came out rectangular and circles as ovals. I feel like it must be a belt problem

    The x side is 18 mm though as if its squashed

    @jb7852 The X of the calibration cube from Thingiverse that you printed, is not in the center in the STL! I see the X off centered in my test cubes also. Note that this does not explain the 18 mm in size!

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Content dated before 7/24/2021 11:53 AM