<p>That it triggers when the nozzle is about 1 mm from the build plate is how it is supposed to work. The <a href="http://www.geeetech.com/wiki/index.php/3DTouch_Auto_Leveling_Sensor" rel="nofollow noreferrer">installation manual</a> describes how to setup the sensor.</p>
<blockquote>
<p>The mount needs to be adjustable so that the distance between the bottom of the sensor (not the pin) needs to be 8.3mm above the tip of the nozzle.</p>
</blockquote>
<p>When taking the above distance into account, the probe should be hitting the build plate first when it is extended. When the probe triggers, it triggers at a certain distance from the nozzle. It is this distance that you need to add as an offset so that the printer knows where the actual Z=0 is. To determine the offset, you home the printer, make sure the Z-offset is zero (with command <code>M851 Z0</code>), then lower the head until a piece of paper gives a little drag when pulled under the nozzle. From the display you can read the offset, e.g. -1.4. With command <code>M851 Z-1.4</code> you set the offset between level and trigger point. Use <code>M500</code> to store the new settings.</p>

CC BY-SA 4.0
2022-04-16T13:58:37.527Z
This is good advice. I'll add that I have found that I get better results if I do a `M851 Z0` to clear the previous offset before I start the homing process. Otherwise, you have to do some math. But I have found that the math never results in an accurate offset. Starting from `M851 Z0` always does. I even bought a feeler gauge because I thought variability in paper thickness might be throwing me off. Oh yeah, make sure you add in the thickness of your paper/gauge. Teaching Tech has a great video. https://www.youtube.com/watch?v=BV11-VOQjMc
Bruno Bronosky
CC BY-SA 4.0
2022-04-16T14:01:53.513Z
This is the best Z offset calibration video in my opinion because they do everything in pronterface making it printer/firmware universal. https://youtu.be/y_1Kg45APko?t=66
Bruno Bronosky
CC BY-SA 4.0
2022-04-16T14:10:40.230Z
@BrunoBronosky Only purists take the paper thickness into account, you generally shouldn't or have a need to do that.
0scar
CC BY-SA 4.0
2022-04-17T13:20:47.223Z
Oscar, in most slicers if you have a layer height of 0.2, the first layer height is 0.3. Paper is about 0.2 also. So, if you don't account for the paper, you are getting a first layer of 0.5 (or 166%) which is pretty excessive. If you are not extruding above 100% to compensate for that, you are likely to have adhesion problems.
Bruno Bronosky
CC BY-SA 4.0
2022-04-17T15:31:12.240Z
@BrunoBronosky Paper thickness is closer to 0.05-0.1 mm, so that is pretty neglectable, if you use 0.2 mm thick paper or a thick feeler gauge I can imagine you might want to compensate, but standard copy paper is not that thick. If you are a purist, compensate, if not don't. I think about 99.5 % of the people with printers don't compensate for the paper thickness. In all my years I've never done this, besides, I never use a 0.3 mm first layer, even not with PETG and never have adhesion problems. You also forget that default extrusion for the first layer is always out of the box more than 100%.
0scar
CC BY-SA 4.0
2022-04-21T03:05:27.647Z
@0scar that would explain how I gouged my bed when I was using paper! I wish I knew which YT video I watched so I could comment on it. #sigh
Bruno Bronosky
CC BY-SA 4.0
2018-09-18T21:26:14.383Z
2022-04-17T15:44:38.123Z
2022-04-17T15:44:38.123Z
0scar
<p>Today I finished building and adjusting a Prusa-Clone printer. The brain is a 32-bit board with Smoothieware on in. To run the auto bed leveling routine I installed a 3DTouch (BLTouch clone, sorry low on cash).
After many headaches, I got everything working fine and I'm happy with the result. Except for one thing...</p>
<p>When the 3DTouch is probing, it is triggered when the nozzle is about 1 mm from the bed. If I set the probe higher, the nozzle crashes onto the bed. If I set the probe lower, the probe would be on the same level of the nozzle, not so good for print time.</p>
<p>Anyone with similar experience or how to sole it?</p>

CC BY-SA 3.0
2018-01-15T14:00:38.040Z
So guessing from your story, you are running Marlin? Have you changed the Z-offset on the printer itself?
Granny
CC BY-SA 3.0
2018-01-16T14:41:54.920Z
No, actually I'm not. I'm running on a Smoothieware powered board (no flag found about that). The question is not about the software, which I know how to manipulate with the offsets, but regarding the hardware, the 3DTouch (also no flag)
Felix Hauser
CC BY-SA 3.0
2018-01-17T07:36:39.240Z
I installed a 3D touch yesterday on my Anet A8 and i had 0 problems setting it up. Are you sure you wired it correctly? And also set it up correctly in the firmware? How are you sure its not firmware related?
Granny
CC BY-SA 3.0
2018-01-20T13:03:05.580Z
The probe works ok and it does what it's supposed to do, it justs triggers way too late. The pin has to be introduced quite a bit before it triggers.
Felix Hauser
CC BY-SA 3.0
2018-01-22T07:40:16.920Z
Probably something wrong with the probe itself then. Cause i have a clone aswell and it touches very lightly.
Granny
<heated-bed><calibration><z-probe><3dtouch>
3DTouch triggers way too close
Felix Hauser
# 3DTouch triggers way too close

(Asked by: username_0 on 2018-01-14)

Today I finished building and adjusting a Prusa-Clone printer. The brain is a 32-bit board with Smoothieware on in. To run the auto bed leveling routine I installed a 3DTouch (BLTouch clone, sorry low on cash).
After many headaches, I got everything working fine and I'm happy with the result. Except for one thing...

When the 3DTouch is probing, it is triggered when the nozzle is about 1 mm from the bed. If I set the probe higher, the nozzle crashes onto the bed. If I set the probe lower, the probe would be on the same level of the nozzle, not so good for print time.

Anyone with similar experience or how to sole it?

**Tags:** heated-bed, calibration, z-probe, 3dtouch
> **Comments:**
> **username_1**: So guessing from your story, you are running Marlin? Have you changed the Z-offset on the printer itself?  
> **username_0**: No, actually I'm not. I'm running on a Smoothieware powered board (no flag found about that). The question is not about the software, which I know how to manipulate with the offsets, but regarding the hardware, the 3DTouch (also no flag)  
> **username_1**: I installed a 3D touch yesterday on my Anet A8 and i had 0 problems setting it up. Are you sure you wired it correctly? And also set it up correctly in the firmware? How are you sure its not firmware related?  
> **username_0**: The probe works ok and it does what it's supposed to do, it justs triggers way too late. The pin has to be introduced quite a bit before it triggers.  
> **username_1**: Probably something wrong with the probe itself then. Cause i have a clone aswell and it touches very lightly.  

---

## 1 answers

### Answer by username_2 on 2018-09-18. Score: 3

That it triggers when the nozzle is about 1 mm from the build plate is how it is supposed to work. The [installation manual](http://www.geeetech.com/wiki/index.php/3DTouch_Auto_Leveling_Sensor) describes how to setup the sensor.

> The mount needs to be adjustable so that the distance between the bottom of the sensor (not the pin) needs to be 8.3mm above the tip of the nozzle.

When taking the above distance into account, the probe should be hitting the build plate first when it is extended. When the probe triggers, it triggers at a certain distance from the nozzle. It is this distance that you need to add as an offset so that the printer knows where the actual Z=0 is. To determine the offset, you home the printer, make sure the Z-offset is zero (with command `M851 Z0`), then lower the head until a piece of paper gives a little drag when pulled under the nozzle. From the display you can read the offset, e.g. -1.4. With command `M851 Z-1.4` you set the offset between level and trigger point. Use `M500` to store the new settings.

> **Comments:**
> **username_3**: This is good advice. I'll add that I have found that I get better results if I do a `M851 Z0` to clear the previous offset before I start the homing process. Otherwise, you have to do some math. But I have found that the math never results in an accurate offset. Starting from `M851 Z0` always does. I even bought a feeler gauge because I thought variability in paper thickness might be throwing me off. Oh yeah, make sure you add in the thickness of your paper/gauge. Teaching Tech has a great video. https://www.youtube.com/watch?v=BV11-VOQjMc  
> **username_3**: This is the best Z offset calibration video in my opinion because they do everything in pronterface making it printer/firmware universal. https://youtu.be/y_1Kg45APko?t=66  
> **username_2**: @BrunoBronosky Only purists take the paper thickness into account, you generally shouldn't or have a need to do that.  
> **username_3**: Oscar, in most slicers if you have a layer height of 0.2, the first layer height is 0.3. Paper is about 0.2 also. So, if you don't account for the paper, you are getting a first layer of 0.5 (or 166%) which is pretty excessive. If you are not extruding above 100% to compensate for that, you are likely to have adhesion problems.  
> **username_2**: @BrunoBronosky Paper thickness is closer to 0.05-0.1 mm, so that is pretty neglectable, if you use 0.2 mm thick paper or a thick feeler gauge I can imagine you might want to compensate, but standard copy paper is not that thick. If you are a purist, compensate, if not don't. I think about 99.5 % of the people with printers don't compensate for the paper thickness. In all my years I've never done this, besides, I never use a 0.3 mm first layer, even not with PETG and never have adhesion problems. You also forget that default extrusion for the first layer is always out of the box more than 100%.  
> **username_3**: @0scar that would explain how I gouged my bed when I was using paper! I wish I knew which YT video I watched so I could comment on it. #sigh  

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