<p>The Z-offset is the distance between the nozzle and the triggerpoint, see e.g. <a href="https://3dprinting.stackexchange.com/a/16605/">this answer</a> of question <a href="https://3dprinting.stackexchange.com/questions/16604/automatic-bed-leveling-abl-with-a-sensor-bltouch-inductive-capacitive-how">Automatic Bed Leveling (ABL) with a sensor (BLTouch, inductive, capacitive), how does it work?</a>.</p>
<p>A &quot;force sensor&quot; as called in the question is actually a <a href="https://en.wikipedia.org/wiki/Strain_gauge" rel="nofollow noreferrer">strain guage</a>; deflection will cause a different electrical resistance which is a measure for the applied stress. These sensors are frequently found in aircraft to measure the strains (as a measure for the stresses) in the structure, e.g. wing spars, (pressure) bulkheads or frames, as part of structural health monitoring (e.g. to compare to the design spectrum of the OEM).</p>
<p>In theory the Z-offset with a strain gauge is non existent if you use such a sensor for <a href="/a/18452/">ABL</a> except that you may need to corect for possible flexing of the bed or the hot end assembly and a paper offset (default distance to allow better flow and adhesion).</p>
<p>However, the system referenced in the question is an <a href="https://www.creality.com/products/creality-ender-3-v3-se" rel="nofollow noreferrer">Ender 3 V3 SE</a> with an ABL system and a strain gauge.</p>
<blockquote>
<p><strong>Relax, Let Auto Leveling Do It</strong><br>
Leveling is the basis of print quality.
Ender-3 V3 SE features a CR Touch sensor for auto leveling
and a strain sensor for auto Z offset.
No need to turn screws or pull a paper.
Just lie back and enjoy the print success.</p>
</blockquote>
<p>This implies that the strain gauge is not used to determine the <a href="/a/15488/">level of the bed</a>, instead the surface  of the build plate is scanned/mapped by the CR Touch (BLTouch clone) sensor. In order to map this scanned surface to the correct height, a test point with the nozzle hitting the buildplate (and as such causing the strain gauge to measure that the nozzle touches the surface) is used to set the Z-offset based on this measurement. Without such a strain gauge, the printer user needs to do that manually; this is the process where you set the offset using the <a href="https://marlinfw.org/docs/gcode/M851.html" rel="nofollow noreferrer"><code>M851</code></a> G-code command. Instead of the user lowering the nozzle until a piece of paper can be dragged with a little resistance to determine the &quot;true zero position&quot; of the Z-axis, the triggering of the strain gauge and the automatic handling by the Creality software will do that for you.</p>
<p>To explain the automatic calculation of the Z-offset in this printer is that the Creality Ender 3 V3 SE first calibrates the Z-offset with the help of a pressure of strain-gauge sensor mounted under the front left corner of the print bed, there is a strain-gauge sensor which can detects deformation on the structure that is mounted on.</p>
<p><a href="https://i.sstatic.net/IqQso.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/IqQso.png" alt="enter image description here" /></a></p>
<p>Knowing the exact position of the nozzle and the position (height) of the trigger point of the leveling sensor, the Z-offset can be calculated and set. That height is then put into the <code>M851</code> G-code command to set the Z-offset. This is exactly how you would do this manually other than you usually use a sheet of paper or a feeler gauge between the nozzle and the bed. The automatic calculation will surely make a correction for that (e.g. there could be play in the nozzle assembly).</p>

CC BY-SA 4.0
2023-12-01T10:45:42.483Z
Thank you, but I don't understand. 'Bed tramming' is: manually adjusting bed screws.  'Automatic bed leveling' (ABL) is: making a mesh (using BL/CRtouch) that the firmware can use to compensate for non-flat beds. UBL is a more advanced version of ABL. That's all irrelevant here, but correct me if I'm wrong. My question is specifically about how to determine the z-offset automatically. If I'm correct, bed tramming and leveling need to happen anyway, automatic or not, and then the only thing left to do is setting the z-offset. That has nothing to do with tramming, ABL, or UBL, right?
Bob Ortiz
CC BY-SA 4.0
2023-12-01T12:50:23.707Z
The Z-offset is only of interest when using a leveling sensor, not a manual leveled bed without ABL. So, yes, it is relevant. I'm sorry you don't understand, but it is linked together. Everything is related to get a good print, you must assure you deliver a bed as level as possible (tramming), the ABL will scan the shape and apply this surface to a certain height. This height is either determined manually or in case of this printer through a strain gauge. There are systems where the strain gauge is used with the nozzle as the levelling sensor, then the Z-offset is zero.
0scar
CC BY-SA 4.0
2023-11-30T15:17:20.140Z
2023-12-01T13:32:27.487Z
2023-12-01T13:32:27.487Z
0scar
<p>The Z offset is just the height difference between tip of the probe pin and the tip of the nozzle.</p>
<p>The auto Z offset feature on the V3 SE works by lowering the toolhead until the tip of the leveling or tramming probe touches the bed surface it then takes that measurement and store it, then it lowers he tool head further until the tip of the nozzle makes contact with the bed, the strain gauge which is the same type of sensor used in a digital scale detects the pressure of the nozzle tip touching the bed
however many steps the Z stepper motor had to make after lowering the tool head for the probe tip to touch the bed is the Z offset.
Z offset just tells the printer  what absolute 0 position is of the Z axis, the level probe probes the bed to check for inconsistencies in the build plate surface</p>

CC BY-SA 4.0
2024-04-20T20:29:07.533Z
2024-04-20T20:29:07.533Z
AR76
<p>The Creality Ender 3 V3 SE, apart from auto bed leveling (ABL), also has a way to calculate the Z-offset automatically. A feature I didn't hear about before.</p>
<p>According to a <a href="https://youtu.be/EL8ehEYPTCk?si=zBleJJzLwV7a9PKw&amp;t=312" rel="nofollow noreferrer">Maker's Muse video</a>, it's based on a force sensor as shown below.</p>
<p><a href="https://i.sstatic.net/SdXDc.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/SdXDc.png" alt="'Force Sensor' in Creality Ender 3 V3 SE" /></a></p>
<p>How does this concept work? How can a force sensor automatically determine the Z-offset?</p>

CC BY-SA 4.0
2023-11-30T15:22:28.420Z
Maybe you should ask the second question in a different question. Your question actually contains multiple questions which makes it more difficult to answer as there are multiple answers. Please split up your question by adding the other questions in a separate question!
0scar
CC BY-SA 4.0
2023-12-01T10:35:40.990Z
Done. https://3dprinting.stackexchange.com/questions/21714/is-there-any-well-documented-auto-z-offset-diy-upgrade-available-for-3d-prin
Bob Ortiz
<creality-ender-3><automatic-bed-leveling><z-offset><sensors>
How can a force sensor automatically determine the Z-offset?
Bob Ortiz
# How can a force sensor automatically determine the Z-offset?

(Asked by: username_0 on 2023-11-30)

The Creality Ender 3 V3 SE, apart from auto bed leveling (ABL), also has a way to calculate the Z-offset automatically. A feature I didn't hear about before.

According to a [Maker's Muse video](https://youtu.be/EL8ehEYPTCk?si=zBleJJzLwV7a9PKw&t=312), it's based on a force sensor as shown below.

[!['Force Sensor' in Creality Ender 3 V3 SE](https://i.sstatic.net/SdXDc.png)](https://i.sstatic.net/SdXDc.png)

How does this concept work? How can a force sensor automatically determine the Z-offset?

**Tags:** creality-ender-3, automatic-bed-leveling, z-offset, sensors
> **Comments:**
> **username_1**: Maybe you should ask the second question in a different question. Your question actually contains multiple questions which makes it more difficult to answer as there are multiple answers. Please split up your question by adding the other questions in a separate question!  
> **username_0**: Done. https://3dprinting.stackexchange.com/questions/21714/is-there-any-well-documented-auto-z-offset-diy-upgrade-available-for-3d-prin  

---

## 2 answers

### Answer by username_1 on 2023-11-30. Score: 3 | Accepted answer

The Z-offset is the distance between the nozzle and the triggerpoint, see e.g. [this answer](https://3dprinting.stackexchange.com/a/16605/) of question [Automatic Bed Leveling (ABL) with a sensor (BLTouch, inductive, capacitive), how does it work?](https://3dprinting.stackexchange.com/questions/16604/automatic-bed-leveling-abl-with-a-sensor-bltouch-inductive-capacitive-how).

A "force sensor" as called in the question is actually a [strain guage](https://en.wikipedia.org/wiki/Strain_gauge); deflection will cause a different electrical resistance which is a measure for the applied stress. These sensors are frequently found in aircraft to measure the strains (as a measure for the stresses) in the structure, e.g. wing spars, (pressure) bulkheads or frames, as part of structural health monitoring (e.g. to compare to the design spectrum of the OEM).

In theory the Z-offset with a strain gauge is non existent if you use such a sensor for [ABL](/a/18452/) except that you may need to corect for possible flexing of the bed or the hot end assembly and a paper offset (default distance to allow better flow and adhesion).

However, the system referenced in the question is an [Ender 3 V3 SE](https://www.creality.com/products/creality-ender-3-v3-se) with an ABL system and a strain gauge.

> **Relax, Let Auto Leveling Do It**  
> Leveling is the basis of print quality.
> Ender-3 V3 SE features a CR Touch sensor for auto leveling
> and a strain sensor for auto Z offset.
> No need to turn screws or pull a paper.
> Just lie back and enjoy the print success.

This implies that the strain gauge is not used to determine the [level of the bed](/a/15488/), instead the surface of the build plate is scanned/mapped by the CR Touch (BLTouch clone) sensor. In order to map this scanned surface to the correct height, a test point with the nozzle hitting the buildplate (and as such causing the strain gauge to measure that the nozzle touches the surface) is used to set the Z-offset based on this measurement. Without such a strain gauge, the printer user needs to do that manually; this is the process where you set the offset using the [`M851`](https://marlinfw.org/docs/gcode/M851.html) G-code command. Instead of the user lowering the nozzle until a piece of paper can be dragged with a little resistance to determine the "true zero position" of the Z-axis, the triggering of the strain gauge and the automatic handling by the Creality software will do that for you.

To explain the automatic calculation of the Z-offset in this printer is that the Creality Ender 3 V3 SE first calibrates the Z-offset with the help of a pressure of strain-gauge sensor mounted under the front left corner of the print bed, there is a strain-gauge sensor which can detects deformation on the structure that is mounted on.

[![enter image description here](https://i.sstatic.net/IqQso.png)](https://i.sstatic.net/IqQso.png)

Knowing the exact position of the nozzle and the position (height) of the trigger point of the leveling sensor, the Z-offset can be calculated and set. That height is then put into the `M851` G-code command to set the Z-offset. This is exactly how you would do this manually other than you usually use a sheet of paper or a feeler gauge between the nozzle and the bed. The automatic calculation will surely make a correction for that (e.g. there could be play in the nozzle assembly).

> **Comments:**
> **username_0**: Thank you, but I don't understand. 'Bed tramming' is: manually adjusting bed screws.  'Automatic bed leveling' (ABL) is: making a mesh (using BL/CRtouch) that the firmware can use to compensate for non-flat beds. UBL is a more advanced version of ABL. That's all irrelevant here, but correct me if I'm wrong. My question is specifically about how to determine the z-offset automatically. If I'm correct, bed tramming and leveling need to happen anyway, automatic or not, and then the only thing left to do is setting the z-offset. That has nothing to do with tramming, ABL, or UBL, right?  
> **username_1**: The Z-offset is only of interest when using a leveling sensor, not a manual leveled bed without ABL. So, yes, it is relevant. I'm sorry you don't understand, but it is linked together. Everything is related to get a good print, you must assure you deliver a bed as level as possible (tramming), the ABL will scan the shape and apply this surface to a certain height. This height is either determined manually or in case of this printer through a strain gauge. There are systems where the strain gauge is used with the nozzle as the levelling sensor, then the Z-offset is zero.  

---

### Answer by username_2 on 2024-04-20. Score: 0

The Z offset is just the height difference between tip of the probe pin and the tip of the nozzle.

The auto Z offset feature on the V3 SE works by lowering the toolhead until the tip of the leveling or tramming probe touches the bed surface it then takes that measurement and store it, then it lowers he tool head further until the tip of the nozzle makes contact with the bed, the strain gauge which is the same type of sensor used in a digital scale detects the pressure of the nozzle tip touching the bed
however many steps the Z stepper motor had to make after lowering the tool head for the probe tip to touch the bed is the Z offset.
Z offset just tells the printer what absolute 0 position is of the Z axis, the level probe probes the bed to check for inconsistencies in the build plate surface


---

