Detla probing adice - inconsistent correction still on delta

@repetier - could you point me in the right direction on this damn delta of mine? I've read the guide for z probing, and think i've followed it properly.

I'm getting inconsistent results and correction on my delta after a G32 s2.

the probe on the delta is using the allen key method which activates a microswitch on the effector.

probe tip sits at 8.5mm from the tip of the nozzle when it's deployed, so this is the value i put into the configurator (Z_PROBE_HEIGHT).

whats happening is that it goes and probes happily and computes a rotation matrix for correction - but the nozzle sits right on the bed during a G1 z0, and autolevelling while printing either pushes the nozzle too far down in some areas or sits about right in others - as if the matrix is either inversed or the probe is measuring incorrectly ?

Do i need to enter a value into Z_PROBE_SWITCHING_DISTANCE to compensate for the travel of the probe to change the switch state ? (this is currently set to a value of 1.2mm which is the best i can measure).


  • Z_PROBE_HEIGHT is not distance when deployed but distance when triggered which is normally less.
    Z_PROBE_SWITCHING_DISTANCE is for repetitions and you will get an error message if it does not untrigger (at least with dev version).

    You should also note that especially for deltas z=0 is not the same over the bed. This depends much on geometry defects and values entered as correction. So what you normally do is using Repetier-Host, make G32 S2, go down to Z= z probe bed distance and start measuring height map. You will see how much it goes up/down and if there is a pattern and correct geometry correction to reduce the errors if required. As a last resort you would use G33 to make first layer stick better.
  • edited January 2017
    Gotcha. So i've been setting the probe height wrong - it should actually be 7.3mm.
    probe height from nozzle (8.5) - switch movement(1.2)).

    I will set the Z_Switch_distance to 1.5.

    As always - thank you ;-)
  • @Repetier - i'm happy the probe is set right now - but the correction rotation still seems to be not applying - i'm watching the nozzle gap during a print and it's not staying consistent, resulting in the 1st layer being very inconsistent in height and extrusion width.

    Could I have missed something ? Does the sampling grid need to be orientated specifically on a delta ?

  • @RhinoRap Here is what I have found that seems to work for me. With autolevelling disabled, I G28 and then do a G30. Then I do a M114. That should equal Max Z-proibe bed dist. + Z-probe height +- 0.02 or 0.03 depending on how accurately the switch changes state. I repeat a couple of times to check. If its off I adjust Z-probe height rehome and check again. Then I do a G32
  • @roko - i'll give that a shot in a bit, cheers dude.

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