3

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

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.

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.

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.

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.

For context, I've had several projects print successfully recently so things had 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.

Trish
  • 22,760
  • 13
  • 53
  • 106
dugost
  • 111
  • 1
  • 1
  • 8

2 Answers2

5

The soldering in the Tevo components is very low quality as I replaced/resoldered most of the end-stops.

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.

To validate micro-switch behavior - lift the Z-axis (about 100mm), then set home position 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.

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)).

profesor79
  • 2,002
  • 1
  • 11
  • 24
4

I'm not familiar with your particular model, so this may not be directly applicable.

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.

Here are three examples, albeit for various models. 12488 , 1829747 ,
2856144

Carl Witthoft
  • 3,073
  • 1
  • 12
  • 18