<p>A z-axis homing issue is giving me an ulcer. I'm hoping someone can help with this.</p>

<p>As per usual, after the Z endstop is triggered on my TEVO Tarantula the gantry raises a bit then slowly lowers back down to the z=0 point established by the trigger. However, the gantry is now lowering well past the point triggered by the endstop. It's forcing the hotend to press down into the bed, and I need to reset the printer to avoid any damage.</p>

<p>I'm at a loss to understand why, and it's making re-leveling the bed impossible. Once I have the bed leveled, an auto home grinds the hotend into the bed.</p>

<p>I've done some cable management in the past couple of days but everything is connected where it should be. The endstops are responding, I've even manually triggered them so I know they're working, but the Z refuses to stop where it should.</p>

<p>I've printed at least once since organizing my cables but the bed wasn't level and then I noticed this issue when homing the Z for re-leveling.</p>

<p>For context, I've had several projects print successfully recently so things <em>had</em> been working fairly well. I haven't made any changes to the Marlin software since originally setting it up months ago. I had been poking around in some settings on the unit but I'm quite sure I reverted everything I tweaked. Regardless, I can't seem to find the menu I had accessed before, and I don't think I've ever had the TEVO successfully save any customizations made via the LCD interface anyway.</p>

[{'answer_id': 7182, 'author': 'profesor79', 'author_id': 9730, 'author_profile': 'https://3dprinting.stackexchange.com/users/9730', 'pm_score': 3, 'selected': False, 'text': '<p>The soldering in the Tevo components is very low quality as I replaced/resoldered most of the end-stops.</p>\n\n<p>As the gantry goes down - please ensure that the cable is not pulled over (no contact) and there is contact on the edge of the acrylic and the end-stop, also the small acrylic switch holder could bend/slip a bit. Finally, the sensor connection to the main board could be dragged by wires that are connected to the hot-end.</p>\n\n<p>To validate micro-switch behavior - lift the Z-axis (about 100mm), then set <code>home position</code> and manually trigger the end-stop switch. That shall lift the Z-axis, so then trigger again to see if that works. You will still have a plenty of time to stop the printer if the switch does not work.</p>\n\n<p>If that works, then the reason could be in slipping edge of the black acrylic plate and the micro-switch. Also validate the mechanical connection (if there is a loosening screw (the small on the switch plate)).</p>\n'}, {'answer_id': 7183, 'author': 'Carl Witthoft', 'author_id': 2191, 'author_profile': 'https://3dprinting.stackexchange.com/users/2191', 'pm_score': 2, 'selected': False, 'text': '<p>I\'m not familiar with your particular model, so this may not be directly applicable.</p>\n\n<p>For many printer models, a swing thru thingiverse.com will find you a replacement z-stop switch mount that uses a threaded screw to set the z-height at which the microswitch fires.  It may well be that you simply need to offset that height by a few mm to get your first layer to mate well with the print bed. </p>\n\n<p>Here are three examples, albeit for various models.  <a href="https://www.thingiverse.com/thing:12488" rel="nofollow noreferrer">12488</a>  ,    <a href="https://www.thingiverse.com/thing:1829747" rel="nofollow noreferrer">1829747</a> ,<br>\n  <a href="https://www.thingiverse.com/thing:2856144" rel="nofollow noreferrer">2856144</a></p>\n'}]
['https://3dprinting.stackexchange.com/questions/7179', 'https://3dprinting.stackexchange.com', 'https://3dprinting.stackexchange.com/users/13208/']