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Bed leveling and homing w Z-min

boonspboonsp
in Extruder & Bed
Hello,`

I just build an hypercube printer which is a core xy system with a bed moving in the Z_direction.
I am experiencing an issue with bed leveling with an inductive sensor with is also configured as an endstop at Z_MIN.

The problem is that while printing the first layers the auto leveling seems only to work in one direction.
At the lowest layers the probe is constantly active due to the compensation by Z_PROBE_HEIGHT.
So so as long as the bed compensation moves the bed away (Z+) from the endstop it is ok. But in the opposite direction (Z-)  the still active endstop seems to prevent the movement. So instead of leveling the bed the systeem is gradually building up an offset. 
I do not seem to be able to find out what I configured wrongly.
Or is this a limitation of the Repetier FW? 
In order to confirm the above I disabled the endstop and homed manually. Then the autobed leveling works in both directions Z- and Z+. 
But I do not like this set up. I also want to have a homing function. Homing to Z max would be an option but I do not like that very much either.
So, can it be fixed to use an inductive sensor for Z_min and stop an bed leveling together.

Any help is appreciated!

Thanks in advance,
Peter
 

Comments

  • RepetierRepetier
    ALWAYS_CHECK_ENDSTOPS 0
    should do the trick. That way end stops are only checked during homing.
  • boonspboonsp
    Thanks.
    That did the trick.
    A bit a pity that I mounted end stops at both sides. The Max sensors are somewhat useless now.
    But what the heck. The system is working properly now and the printing performance is pretty good if not excellent, thanks to the bed leveling.

    Thanks again,
    Peter
     


  • RepetierRepetier
    YOu can add a sensor at z max and home z max. Then z probe is not a end stop and is only used for probing.
  • recoushrecoush
    Repetier said:
    YOu can add a sensor at z max and home z max. Then z probe is not a end stop and is only used for probing.
    No hijack intended, can you elaborate?
    This is this may come in handy.
    Thanks
    Recoush
  • RepetierRepetier
    Just think bed is rotated 10° right side down so effect is easier to see. z min stops any z move so a real z min endstop needs to stop at the lowest point - here right side. If homing z is done at x min it would press nozzle some 35mm into the bed on the left side until it triggers. Not useful. On the other side a z min z probe moves with extruder so measuring a x=0 it just stops earlier and can then put in the rotation it knows to keep that level.

    Homing to z max has no obstacles to hit so it is save. All you need to set is a move back after hitting endstop so you still get go up/down at z max according to bed correction requirements.
  • recoushrecoush
    edited February 2019
    lets see if i am following this correctly, essentially the end stops switches are reversed Zed max for me 660mm down in my case is now zed Min and Zed max becomes Zed Probe at the top to stop the Overshot and the real Z home is zed Max seems like the new Zed min would be going the wrong way? (my setup is a Large frame CoreXY) roughly 400x400x660
  • RepetierRepetier
    No need to use zmax for z probe. Well pin names are just names so it only matters for what you use it. You cal also put ymax pin on zmax endstop if you like. Important is when you have zmax homing that you have no zmin endstop defined. You only define z probe connected to whatever you want. And of course set homing direction to 1.
    #define ENDSTOP_Z_BACK_ON_HOME 2
    is also required so result is always valid and xy moves at zmax do not hit zmax endstop during moves with bed correction active.
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