z probe height offsets in wrong direction.

I made a linear hall effect sensor z probe. The one in this video I printed a rail and spring for the probe attatched to a wire and servo for lifting out of the way. Everything works great except the z probe height modifier seems to be inverted. For example, I set the amplifier to trigger at .3 mm and enter .3 for probe height and the nozzle will instead press into the bed .3 mm. Ive had it work before I just cant figure it out.


  • So your z probe height is 0 and you should increase sensitivity! Consider it is not the distance of bed to probe when it triggers but distance of nozzle to bed when it triggers.
  • Yes I understand that completely. (I meant .3 is height from nozzle to platform) wouldn't you expect that if I added the difference to " z probe height" the nozzle would be at platform level? No, it just goes further into the bed. Could this be because my sensor triggers on high?
  • Did I read somewhere that z probe height is added to max z in eeprom with s2? Because I am subtracting z probe height from max z to get it to work.
  • Maybe my z endstop? I didn't think of that before
  • You are homing to z max? Make sure bead coating is set 0 as this changes result when homing.

    S2 computes new height by adding the difference between old and new z from z probing as this is the change measured.

    Where z probe triggers /high/low) is not important if configured correctly. As long as M119 shows L when not triggered and H when triggered it is used correctly.

    To understand how to change always think when you trigger you are at z probe height for z while it assumes a different height from z used for homing. The difference is the error which gets corrected. So higher z probe height means it thinks it has a higher z at that point so it needs to increase z height so next homing is then really at that z height.
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