<p>I was surprised to find this out as I haven't heard or read anything about this before in any 'calibration instruction' or 'calibration guide'.</p>
<p>However, as I just found out, the mriscoc firmware gladly has a very easy way of changing this from the menu as documented on the <a href="https://github.com/mriscoc/Ender3V2S1/wiki/How-to-set-the-home-offsets" rel="nofollow noreferrer">mriscoc GitHub Wiki</a>.</p>
<p>As I already took measurements as shown in the question and as my bed is 235x235 mm. I simply used the LCD menu to go to <strong>Advanced &gt; Physical settings</strong> and then for printer 'Owl' I changed it to:</p>
<pre><code>X_MIN_POS = 5
X_MAX_POS = 240
Y_MIN_POS = 5
Y_MAX_POS = 240
</code></pre>
<p>For 'Fox' I changed it to:</p>
<pre><code>X_MIN_POS = 2
X_MAX_POS = 237
Y_MIN_POS = 7
Y_MAX_POS = 242
</code></pre>
<p>I also set the bed size to 235x235 for both printers. I reprinted the test file on each printer and now it is perfectly and equally aligned for each. The question still remains how this could be so far off the center and off identical printers.</p>

CC BY-SA 4.0
2024-01-06T10:46:23.963Z
What offsets have you set for each printer? Look at the response of a M503 in a console (in OctoPrint e.g.) to see what is listed behind M206.
0scar
CC BY-SA 4.0
2024-01-06T21:04:16.980Z
The only 'offset' that is reported after running M503 is in G-code M851 (not M206). Does that make sense? And it's for Fox `M851 X-41.50 Y-7.00 Z-1.13 ; (mm)` and for Owl `M851 X-41.50 Y-7.00 Z-1.06 ; (mm)`, so except for the Z-offset no difference.
Bob Ortiz
CC BY-SA 4.0
2024-01-07T09:10:16.233Z
Are the 2 printers exactly the same, it sounds like the bed or the endstops are mounted differently.
0scar
CC BY-SA 4.0
2024-01-07T21:14:30.143Z
I guess there is too little space in the frame for the bed to be mounted so differently. But I have to do some additional measurements to try to spot differences. It looks not very different to me, but I'll measure it when I get to it.
Bob Ortiz
CC BY-SA 4.0
2024-01-07T23:12:03.760Z
It it a very strange thing happening, it puzzles me. Hope you have some additional information.
0scar
CC BY-SA 4.0
2024-01-07T23:34:27.200Z
Me too, and I also want to understand why so I will post more info when I have time to measure more things.
Bob Ortiz
CC BY-SA 4.0
2024-01-08T18:45:55.483Z
I've added endstop measurement photos in the question and they are basically identical for the X-axis and Y-axis of each printer, so is the bed location. So, still in unknown.
Bob Ortiz
CC BY-SA 4.0
2024-01-08T22:06:01.267Z
I never like the way the bed is sized according to e.g. that firmware configuration and others use. Basically, the corner of the bed should be (0,0), not (5,5) for Owl. We used to express the minimum positions with negative values to indicate there is space between the endstop and the origin. If you do this, the bed itself is always 0 to 235 and not 5 to 240. Now that you added measurements, you still need to look into the actual position of the build surface mounting relative to the endstops.
0scar
CC BY-SA 4.0
2024-01-08T22:54:00.367Z
That won't be too hard for the X-axis as it is static to the build surface but the Y-axis is a moving bed, how would I measure that relative to the endstops? With the bed at the max. other end?
Bob Ortiz
CC BY-SA 4.0
2024-01-05T17:21:47.697Z
2024-01-06T21:33:34.430Z
2024-01-06T21:33:34.430Z
Bob Ortiz
<p>Perhaps the hot-end or end stops of one of the printers are located in a slightly different location. That's why there is a <a href="https://github.com/mriscoc/Ender3V2S1/wiki/Calibration-Guides" rel="nofollow noreferrer">calibration guide</a> to be able to correct that.</p>

CC BY-SA 4.0
2024-01-07T21:15:13.053Z
Thanks, I will try to do additional measurements later to try and find out the difference and report here if I found it.
Bob Ortiz
CC BY-SA 4.0
2024-01-08T18:45:04.337Z
I've added endstop measurement photos in the question and they are basically identical for the X-axis and Y-axis of each printer, so is the bed location.
Bob Ortiz
CC BY-SA 4.0
2024-01-07T06:47:01.727Z
2024-01-07T13:55:58.123Z
2024-01-07T13:55:58.123Z
Miguel Risco-Castillo
<p>When pushing the limits of the bed size (235x235 mm) for two Creality Ender 3 V2 printers running the same mriscoc firmware and the same config and upgrades. I noticed that despite using the same G-code for these two fairly identical printers resulted in offsets that was not accounted for.</p>
<p>I sliced and printed a test model <a href="https://www.thingiverse.com/thing:2280529/files" rel="nofollow noreferrer">175mm_bed_center_calibration_crosshair.stl from Thingiverse.com</a> and when slicing in Cura it is perfectly centered as shown below:</p>
<p><a href="https://i.sstatic.net/9EC62m.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/9EC62m.png" alt="test center model" /></a></p>
<p>However when printed on each printer and measured, the position in mm for both printers (namely Owl and Fox) are off as shown below:</p>
<p><a href="https://i.sstatic.net/UZLXt.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/UZLXt.png" alt="measurement of center position for two printers" /></a></p>
<p>I would like to setup the printers fairly similar, I only print from OctoPi over USB to these printers, one Pi for each printer, so that I can slice once and use the same G-code on both printers. How do I calibrate this without recompiling the firmware? Can I setup a start or end G-code in OctoPi per printer to set a proper center offset? And moreover, why does this happen for identical printers? Shouldn't the tolerance be much smaller than 3 mm difference horizontally and 2 mm vertically (shown from above)?</p>
<h2>Additional measurements</h2>
<p>For reference, based on request in the comments some measurements of the end stops relative to the frame of the XY-axes of both printers.</p>
<p>Measurement of the Z-axes are irrelevant for this purpose.</p>
<p><strong>Owl Y-axis Endstop (85mm)</strong>
<a href="https://i.sstatic.net/djshl.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/djshl.jpg" alt="Owl Y-axis Endstop" /></a></p>
<p><strong>Fox Y-axis Endstop (85mm)</strong>
<a href="https://i.sstatic.net/rJUbf.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/rJUbf.jpg" alt="Fox Y-axis Endstop" /></a></p>
<p><strong>Owl X-axis Endstop (45mm)</strong>
<a href="https://i.sstatic.net/1R0T7.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/1R0T7.jpg" alt="Owl X-axis Endstop" /></a></p>
<p><strong>Fox X-Axis Endstop (45mm)</strong>
<a href="https://i.sstatic.net/BY9Wi.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/BY9Wi.jpg" alt="Fox X-Axis Endstop" /></a></p>
<p>I also measured the <strong>size between the bed and the frame</strong> as shown below and it's precisely 7mm <strong>on each side</strong> of the bed <strong>on both printers</strong>.</p>
<p><a href="https://i.sstatic.net/UlgAu.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/UlgAu.jpg" alt="Space between bed and frame" /></a></p>
<p>I think these are the only measurements that make sense, but correct me if you have other suggestions for measuring it.</p>
<p>Also, the only offset that is reported after running the M503 G-code in  G-cod M851 it not relevant for centering, the Z-offset. For Fox <code>M851 X-41.50 Y-7.00 Z-1.13 ; (mm)</code> and for Owl <code>M851 X-41.50 Y-7.00 Z-1.06 ; (mm)</code>.</p>

CC BY-SA 4.0
2024-01-07T02:44:27.957Z
Are the endstops mounted differently?
R.. GitHub STOP HELPING ICE
CC BY-SA 4.0
2024-01-07T23:16:08.243Z
Familiar center print object! 
0scar
CC BY-SA 4.0
2024-01-07T23:36:28.533Z
I didn't even know. Small world 
Bob Ortiz
CC BY-SA 4.0
2024-01-08T21:53:29.283Z
I guess you imply 5, 5 (x, y) for Owl and 3 and 7 *milimeter* for Fox instead of 3 and 7 *centimeter* in the title?
0scar
CC BY-SA 4.0
2024-01-08T22:50:33.633Z
Unbelievably dumb mistake. I'm sorry, brain error.
Bob Ortiz
<creality-ender-3><calibration><bed><mriscoc><octopi>
Why do two identical Creality Ender 3 V2 printers have a center that is 3 mm off from each other and 7 mm off expected and how to calibrate it?
Bob Ortiz
# Why do two identical Creality Ender 3 V2 printers have a center that is 3 mm off from each other and 7 mm off expected and how to calibrate it?

(Asked by: username_0 on 2024-01-05)

When pushing the limits of the bed size (235x235 mm) for two Creality Ender 3 V2 printers running the same mriscoc firmware and the same config and upgrades. I noticed that despite using the same G-code for these two fairly identical printers resulted in offsets that was not accounted for.

I sliced and printed a test model [175mm\_bed\_center\_calibration\_crosshair.stl from Thingiverse.com](https://www.thingiverse.com/thing:2280529/files) and when slicing in Cura it is perfectly centered as shown below:

[![test center model](https://i.sstatic.net/9EC62m.png)](https://i.sstatic.net/9EC62m.png)

However when printed on each printer and measured, the position in mm for both printers (namely Owl and Fox) are off as shown below:

[![measurement of center position for two printers](https://i.sstatic.net/UZLXt.png)](https://i.sstatic.net/UZLXt.png)

I would like to setup the printers fairly similar, I only print from OctoPi over USB to these printers, one Pi for each printer, so that I can slice once and use the same G-code on both printers. How do I calibrate this without recompiling the firmware? Can I setup a start or end G-code in OctoPi per printer to set a proper center offset? And moreover, why does this happen for identical printers? Shouldn't the tolerance be much smaller than 3 mm difference horizontally and 2 mm vertically (shown from above)?

## Additional measurements

For reference, based on request in the comments some measurements of the end stops relative to the frame of the XY-axes of both printers.

Measurement of the Z-axes are irrelevant for this purpose.

**Owl Y-axis Endstop (85mm)**
[![Owl Y-axis Endstop](https://i.sstatic.net/djshl.jpg)](https://i.sstatic.net/djshl.jpg)

**Fox Y-axis Endstop (85mm)**
[![Fox Y-axis Endstop](https://i.sstatic.net/rJUbf.jpg)](https://i.sstatic.net/rJUbf.jpg)

**Owl X-axis Endstop (45mm)**
[![Owl X-axis Endstop](https://i.sstatic.net/1R0T7.jpg)](https://i.sstatic.net/1R0T7.jpg)

**Fox X-Axis Endstop (45mm)**
[![Fox X-Axis Endstop](https://i.sstatic.net/BY9Wi.jpg)](https://i.sstatic.net/BY9Wi.jpg)

I also measured the **size between the bed and the frame** as shown below and it's precisely 7mm **on each side** of the bed **on both printers**.

[![Space between bed and frame](https://i.sstatic.net/UlgAu.jpg)](https://i.sstatic.net/UlgAu.jpg)

I think these are the only measurements that make sense, but correct me if you have other suggestions for measuring it.

Also, the only offset that is reported after running the M503 G-code in G-cod M851 it not relevant for centering, the Z-offset. For Fox `M851 X-41.50 Y-7.00 Z-1.13 ; (mm)` and for Owl `M851 X-41.50 Y-7.00 Z-1.06 ; (mm)`.

**Tags:** creality-ender-3, calibration, bed, mriscoc, octopi

> **Comments:**
> **username_1**: Are the endstops mounted differently?  
> **username_2**: Familiar center print object!   
> **username_0**: I didn't even know. Small world   
> **username_2**: I guess you imply 5, 5 (x, y) for Owl and 3 and 7 *milimeter* for Fox instead of 3 and 7 *centimeter* in the title?  
> **username_0**: Unbelievably dumb mistake. I'm sorry, brain error.  

---

## 2 answers

### Answer by username_0 on 2024-01-05. Score: 1 | Accepted answer

I was surprised to find this out as I haven't heard or read anything about this before in any 'calibration instruction' or 'calibration guide'.

However, as I just found out, the mriscoc firmware gladly has a very easy way of changing this from the menu as documented on the [mriscoc GitHub Wiki](https://github.com/mriscoc/Ender3V2S1/wiki/How-to-set-the-home-offsets).

As I already took measurements as shown in the question and as my bed is 235x235 mm. I simply used the LCD menu to go to **Advanced > Physical settings** and then for printer 'Owl' I changed it to:

```
X_MIN_POS = 5
X_MAX_POS = 240
Y_MIN_POS = 5
Y_MAX_POS = 240

```

For 'Fox' I changed it to:

```
X_MIN_POS = 2
X_MAX_POS = 237
Y_MIN_POS = 7
Y_MAX_POS = 242

```

I also set the bed size to 235x235 for both printers. I reprinted the test file on each printer and now it is perfectly and equally aligned for each. The question still remains how this could be so far off the center and off identical printers.

> **Comments:**
> **username_2**: What offsets have you set for each printer? Look at the response of a M503 in a console (in OctoPrint e.g.) to see what is listed behind M206.  
> **username_0**: The only 'offset' that is reported after running M503 is in G-code M851 (not M206). Does that make sense? And it's for Fox `M851 X-41.50 Y-7.00 Z-1.13 ; (mm)` and for Owl `M851 X-41.50 Y-7.00 Z-1.06 ; (mm)`, so except for the Z-offset no difference.  
> **username_2**: Are the 2 printers exactly the same, it sounds like the bed or the endstops are mounted differently.  
> **username_0**: I guess there is too little space in the frame for the bed to be mounted so differently. But I have to do some additional measurements to try to spot differences. It looks not very different to me, but I'll measure it when I get to it.  
> **username_2**: It it a very strange thing happening, it puzzles me. Hope you have some additional information.  
> **username_0**: Me too, and I also want to understand why so I will post more info when I have time to measure more things.  
> **username_0**: I've added endstop measurement photos in the question and they are basically identical for the X-axis and Y-axis of each printer, so is the bed location. So, still in unknown.  
> **username_2**: I never like the way the bed is sized according to e.g. that firmware configuration and others use. Basically, the corner of the bed should be (0,0), not (5,5) for Owl. We used to express the minimum positions with negative values to indicate there is space between the endstop and the origin. If you do this, the bed itself is always 0 to 235 and not 5 to 240. Now that you added measurements, you still need to look into the actual position of the build surface mounting relative to the endstops.  
> **username_0**: That won't be too hard for the X-axis as it is static to the build surface but the Y-axis is a moving bed, how would I measure that relative to the endstops? With the bed at the max. other end?  

---

### Answer by username_3 on 2024-01-07. Score: 3

Perhaps the hot-end or end stops of one of the printers are located in a slightly different location. That's why there is a [calibration guide](https://github.com/mriscoc/Ender3V2S1/wiki/Calibration-Guides) to be able to correct that.

> **Comments:**
> **username_0**: Thanks, I will try to do additional measurements later to try and find out the difference and report here if I found it.  
> **username_0**: I've added endstop measurement photos in the question and they are basically identical for the X-axis and Y-axis of each printer, so is the bed location.  

---

