Z Probing, Understanding Max Z-probe -bed distance


Having great difficulty setting up skeinforge using repetier firmware and host. Will be posting to reprap forum in regards to skeinforge in a moment but would like to try and understand this better too.
Trying to probe Z Min with inductive sensor to Aluminum heated bed.

I have set my z probe height to around 1.5 that is a positive value, and that is the value that after homing Z sets the probe head just slightly off the bed where a piece of paper can slide between with slight resistance. I have also set max z-probe -bed distance to 5. when that happens probe keeps just above bed (like .2mm) while moving from point to point autoleveling, I set this to -3 and have a nice clearance of 2-3mm above bed.  When I set the value negative I appear to have a massive problem with z being that after 3 layers at .2 each I have a thickness of 2.6mm or so of printed part.  I realize I am having issues setting flowrate as well.  Setting z steps per mm to calculate 4000 and measure the mechanics of 100mm z move and it measures correctly within 1mm.

In short for z min probing bed, should probe height be positive?  Should Max Z probe - bed distance be positive?  What is bed distance? Max z height is 160.

Thank you for your time and efforts!!


  • Probing height is our preferred height for measuring and MUST be positive (otherwise it makes no sense). z probe bed distance is distance to nozzle when it triggers. For inductive sensors always positive.

    Remember to disable bed when measuring!
  • Thanks for the explanation.  Your dedicated support is much appreciated!!!

    Have been struggling since downloading repetier firmware 12-27-2015 (just saw tonight that you released an update about firmware on 1-3-2016 regarding bed correction method).

    In short I believe my problem configuring skeinforge is not skeinforge but related to z axis...I cross referenced using repetier firmware, matter control host, and matter slice problem repeats.  I move to X90 Y90 and home Z, set Z probe offset touch off on a piece of paper and good to go, when I home at bed before start repeats and is just above of the surface of the bed.  But the problem is that when it starts to print, first layer thickness should be .15mm and by canceling the print and using feeler gages the nozzle is 1.01mm off of the bed, taking into consideration it is within 5mm X and Y of part center aka Z delta should be relatively small.  So in short even when I got the first layer set the layer height of .2mm was larger than it should be. I have checked Z calibration with steps per mm and that is spot on, had used a value of approx. 3900 when 4000 should be nominal.  Turns out plugging in 4000 and moving Z up 100mm I am within 1mm (measured with a ruler), so 1 mm over 100 does not equate to 1mm over .2mm layer.  Not trying to over explain, was trying to keep this brief, I know you have a lot to read.

    Will the bed correction method take care of this?  I will find out in about 18hrs when I get to try this again, but wanted to get your thoughts. Any other parameters that I should look at/modify?

    Thanks again for the help!
  • Sorry, I could not really follow your problem. Not sure what you do and expect. Maybe a more log like description would help more including commands and returned answers.

    One thing you should be aware of is setting #define ENDSTOP_Z_BACK_ON_HOME 10 or higher. Only that way you do not touch too fast the endstops since deltas have after homing 0mm play to the sides and must move down. Printable radius grows with decreasing z so going directly down a bit helps preventing illegal moves from the top, also you still can not go to the fully sides.

  • Appears, after updating to the newer firmware things are much closer.  When performing G32 S2 (9 point 3x3 grid) the light on the inductive sensor is only triggering at some spots, which I would presume is not providing the most accurate plane.  Z probe height would not be the parameter to change.  Would I decrease Z bed height - probe height??

    Will play with Z probe height to offset for proper first layer adhession.  
  • This solved the issue described directly above...#define ENDSTOP_Z_BACK_ON_HOME 10

Sign In or Register to comment.