<p>If the cad model was imported from Solidworks into Simplify3D. Push "Center and Arrange" button to place the model in the middle of the Heat Bed. There might be a gap between the object and bed level that is hard to see. </p>

CC BY-SA 4.0
2018-12-07T10:37:01.817Z
2018-12-07T10:37:01.817Z
2012User
<p>I've built a DIY 3D printer similar to Prusa i3. It does <em>homing</em> and <em>bed leveling</em> very well with a PNP Lj12a3_4_Z_BY sensor using <code>G28</code> and <code>G29</code>.</p>

<p><a href="https://i.sstatic.net/E9Cag.jpg" rel="nofollow noreferrer" title="Lj12a3_4_Z_BY"><img src="https://i.sstatic.net/E9Cag.jpg" alt="Lj12a3_4_Z_BY" title="Lj12a3_4_Z_BY"></a></p>

<p>However, when I push the print button on Pronterface or Simplify3D, Z axis goes up about 20mm and starts printing in air. I can't figure out what is going wrong.</p>

<z-axis><bed-leveling><simplify3d><z-probe><pronterface>
Why does my DIY printer start printing in air?
2012User
# Why does my DIY printer start printing in air?

(Asked by: username_0 on 2018-12-05)

I've built a DIY 3D printer similar to Prusa i3. It does *homing* and *bed leveling* very well with a PNP Lj12a3\_4\_Z\_BY sensor using `G28` and `G29`.

[![Lj12a3_4_Z_BY](https://i.sstatic.net/E9Cag.jpg "Lj12a3_4_Z_BY")](https://i.sstatic.net/E9Cag.jpg "Lj12a3_4_Z_BY")

However, when I push the print button on Pronterface or Simplify3D, Z axis goes up about 20mm and starts printing in air. I can't figure out what is going wrong.

**Tags:** z-axis, bed-leveling, simplify3d, z-probe, pronterface

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## 1 answers

### Answer by username_0 on 2018-12-07. Score: 3 | Accepted answer

If the cad model was imported from Solidworks into Simplify3D. Push "Center and Arrange" button to place the model in the middle of the Heat Bed. There might be a gap between the object and bed level that is hard to see.


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