Find center of cavity (with Z-Probe)

  • Dear Forum,

    I am trying to find the center of a round cavity by using M675 and a Z-Probe (Precision Piezo).

    It is configured like this:

    M558 P1 C"!" H4 F220 T200            
    G31 P520 X0 Y0 Z0    

    My M675 command is:

    M675 Y R4 P0 F600

    This works very well in the minimum direction of the axis (the Z-Probe value is around 515 when idle). As soon as it probes the max direction of the cavity I am struggling to get a trigger bigger than 520.

    I noticed that my Z-Probe value goes down to under 500 when hitting the round cavity in max direction.

    I guess when the piezo disc is being squished when probing into the min direction (causing a Z-Probe value bigger than 520). When probing the max direction, then it seems that because the piezo disk has less pressure on it, thats why the Z-Probe value goes under 500.

    Any idea what I can do about this? Ideally one could also specify a "min trigger value"...

    Thank you kindly.


  • @vollnormal I assume you are using analog output from the PP since you are talking about analog values. In that case you can modify trigger value before the sensing move... e.g. I'm doing this:

    G31 P{sensors.probes[0].value[0] + 8}

    but you need RRF v3 for this to work

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