<p>Using automatic bed leveling assists you in getting the print to stick better to the build platform as a result of the print head following the non-uniform geometry or tilt of the build plate.</p>
<p>In, e.g. Marlin Firmware, the bed level correction is fading out over a predefined distance, this is determined by the constant <code>#define ENABLE_LEVELING_FADE_HEIGHT</code> in the printer firmware <a href="https://github.com/MarlinFirmware/Marlin/blob/1.1.x/Marlin/Configuration.h" rel="nofollow noreferrer">Configuration.h</a> file  and the height can be set with <code>M420 Z&lt;height&gt;</code> (see <a href="https://reprap.org/wiki/G-code#M420:_Leveling_On.2FOff.2FFade_.28Marlin.29" rel="nofollow noreferrer">here</a>).</p>
<blockquote>
<pre><code>M420 S1  ; Enable compensation using current grid/mesh
M420 Z10 ; Gradually reduce compensation until Z=10
</code></pre>
</blockquote>
<p>If Z equals zero, leveling compensation will be fully applied to all layers of the print object.</p>
<p>Yes, a cube will not be perfectly cubic, that is why even with auto bed leveling you need to provide a bed as level as possible, it only should correct for very small deviations.</p>
<p>When the print is smaller than the fade out height, you would indeed get a sheared print, if larger, then the top of the print would be level with respect to the reference plane (machine true; this is the level of the X-Y plane, basically the level of the hot end carriage). Note that that still can be skew if the printer is improperly calibrated (e.g. when using 2 Z steppers or misalignment of the height on either side).</p>

CC BY-SA 4.0
2018-09-13T06:42:48.583Z
2021-08-15T17:27:35.150Z
2021-08-15T17:27:35.150Z
0scar
<p><em>I asked this question as a small question under an <a href="https://3dprinting.stackexchange.com/a/6365/5740">answer</a> of another <a href="https://3dprinting.stackexchange.com/questions/6364/how-bed-leveling-is-achieved-without-table-screws">question (How bed leveling is achieved without table screws?)</a>, but have been asked to post this as a separate question to answer it with more detail conform SE policy.</em></p>

<hr>

<p>One question with respect to automatic bed leveling (also known as ABL): If the bed is tilted and the auto leveling measured this and then the printer adjust the z axis over the position on the bed, will a x-y-point on the first layer be located exactly under the (in model) same x-y-point in a higher layer, or will it be shifted to? I mean, if the bed is 1 mm lower on one side over 10 cm then a top corner of a 10-cm-cube should be also 1 mm shifted, so that the cube still is real cubic and not sheared.</p>

<bed-leveling>
Does auto leveling result in sheared prints?
Horitsu
# Does auto leveling result in sheared prints?

(Asked by: username_0 on 2018-09-13)

*I asked this question as a small question under an [answer](https://3dprinting.stackexchange.com/a/6365/5740) of another [question (How bed leveling is achieved without table screws?)](https://3dprinting.stackexchange.com/questions/6364/how-bed-leveling-is-achieved-without-table-screws), but have been asked to post this as a separate question to answer it with more detail conform SE policy.*

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One question with respect to automatic bed leveling (also known as ABL): If the bed is tilted and the auto leveling measured this and then the printer adjust the z axis over the position on the bed, will a x-y-point on the first layer be located exactly under the (in model) same x-y-point in a higher layer, or will it be shifted to? I mean, if the bed is 1 mm lower on one side over 10 cm then a top corner of a 10-cm-cube should be also 1 mm shifted, so that the cube still is real cubic and not sheared.

**Tags:** bed-leveling


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## 1 answers

### Answer by username_1 on 2018-09-13. Score: 8 | Accepted answer

Using automatic bed leveling assists you in getting the print to stick better to the build platform as a result of the print head following the non-uniform geometry or tilt of the build plate.

In, e.g. Marlin Firmware, the bed level correction is fading out over a predefined distance, this is determined by the constant `#define ENABLE_LEVELING_FADE_HEIGHT` in the printer firmware [Configuration.h](https://github.com/MarlinFirmware/Marlin/blob/1.1.x/Marlin/Configuration.h) file and the height can be set with `M420 Z<height>` (see [here](https://reprap.org/wiki/G-code#M420:_Leveling_On.2FOff.2FFade_.28Marlin.29)).

> ```
> M420 S1  ; Enable compensation using current grid/mesh
> M420 Z10 ; Gradually reduce compensation until Z=10
>
> ```

If Z equals zero, leveling compensation will be fully applied to all layers of the print object.

Yes, a cube will not be perfectly cubic, that is why even with auto bed leveling you need to provide a bed as level as possible, it only should correct for very small deviations.

When the print is smaller than the fade out height, you would indeed get a sheared print, if larger, then the top of the print would be level with respect to the reference plane (machine true; this is the level of the X-Y plane, basically the level of the hot end carriage). Note that that still can be skew if the printer is improperly calibrated (e.g. when using 2 Z steppers or misalignment of the height on either side).


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