<p>You must invert the logic of the endstop Z_min.</p>
<h1>define Z_MIN_ENDSTOP_INVERTING true</h1>
<p>To</p>
<h1>define Z_MIN_ENDSTOP_INVERTING False</h1>

CC BY-SA 4.0
2019-02-03T05:22:46.880Z
@lukaspanic If your table is colliding with the nozzle, you must invert the Z motor cables
3D TECH BRASIL
CC BY-SA 4.0
2019-02-03T23:45:31.953Z
Nope, that didn't change anything. It's still doing the exact same thing. If the BLTouch would be extended it would probably be fine but it doesn't seem to know it's supposed to do anything.
lukaspanic
CC BY-SA 4.0
2019-02-03T05:19:39.720Z
2019-02-03T05:19:39.720Z
2020-06-18T08:29:41.667Z
3D TECH BRASIL
<p>I have an Anet A8 with Marlin Firmware 1.1.9 and I installed a BLTouch sensor. When I start the system the BLTouch does its self test (extend and retract the probe twice) and then lights up red. When I "Auto Home", it homes X, then Y and then extends and retracts the probe and moves up a few millimeters. Then with the probe retracted it moves down until the nozzle crashes into the table. The same happens when I select "Level bed".</p>

<p>Safe Homing is active.</p>

<p>What am I doing wrong?</p>

<p>My current Configuration.h can be found <a href="https://drive.google.com/open?id=1yaL3DLFM5z6QeZ-q0CUa1X6bw25cdVWK" rel="nofollow noreferrer">here</a>.</p>

<z-axis><anet-a8><bltouch><homing>
Anet A8 & BLTouch not homing Z
lukaspanic
# Anet A8 & BLTouch not homing Z

(Asked by: username_0 on 2019-02-03)

I have an Anet A8 with Marlin Firmware 1.1.9 and I installed a BLTouch sensor. When I start the system the BLTouch does its self test (extend and retract the probe twice) and then lights up red. When I "Auto Home", it homes X, then Y and then extends and retracts the probe and moves up a few millimeters. Then with the probe retracted it moves down until the nozzle crashes into the table. The same happens when I select "Level bed".

Safe Homing is active.

What am I doing wrong?

My current Configuration.h can be found [here](https://drive.google.com/open?id=1yaL3DLFM5z6QeZ-q0CUa1X6bw25cdVWK).

**Tags:** z-axis, anet-a8, bltouch, homing


---

## 1 answers

### Answer by username_1 on 2019-02-03. Score: 1

You must invert the logic of the endstop Z\_min.

# define Z\_MIN\_ENDSTOP\_INVERTING true

To

# define Z\_MIN\_ENDSTOP\_INVERTING False

> **Comments:**
> **username_1**: @username_0 If your table is colliding with the nozzle, you must invert the Z motor cables  
> **username_0**: Nope, that didn't change anything. It's still doing the exact same thing. If the BLTouch would be extended it would probably be fine but it doesn't seem to know it's supposed to do anything.  

---

