z-leveling again...

Comments

• Repetier

  April 2017

  Looks like you have a z min endstup and a z probe. That is a combination that does not work. You need to always home z min using z probe in that case. Otherwise you measure something using z probe and for homing you ignore everything and you use the not calibrated z min endstop whcih stops at a compületely different and unknown height and you can go lower even if rotation would require that.
• HenryLoenwind

  April 2017

  Repetier said:

   not calibrated z min endstop whcih stops at a compületely different and unknown height

  Isn't that exactly what z-leveling is supposed to do? Measure the offset between the endstop and bed surface?

  
  

  I had a quick look, and to me it seems this may not too hard to implement, in Printer::HomeZAxis():

  
  

  currentPosition[Z_AXIS] = 0;

  
  

  needs to be either replaced with bedleveling height at the current xy, or the axis needs to be moved up that far. And obviously this offset needs to be remembered so the next leveling can undo it to work from real coordinates.

  
  

  On the other hand, putting that value into

  
  

          Printer::zBabysteps = 0;
  

  
  

  may be the even simpler solution. No need to worry about side effects.Other than the detail that leveling compensation most probably ignores it so the bed may be out of of compensation range (only 1mm by default, I think). Also, this needs to be updated after running the leveling, but for the "detachable probe" case you do this manually and then run a print job that does homing, so it isn't that important.

  
  

  I'm willing to try this out, what would be the best way to get the computed bed height? (Probably whatever G30 does, I'd guess )
• Repetier

  April 2017

  It is not so easy. z min endstop is where moves stop - no more down from that height. Soit must be at a position below bed surface (you hear the problem) otherwise you might need to go below z min trigger depending on rotation of bed. So going below bed surface means bed needs some not too hard springs or you might damage something.

  
  

  This can be completely avoided by using z probe for z min. All it needs to know is x and y position so it compute backwards from known rotation what height is.

  
  

  In your solution you could use bed coating to fix the gap. You need to set it manually since autoleveling levels surface but does not compute an offset to z min as this is a unsupported combination.