Install Z-Probing WITHOUT a Z Max end switch?

I have an Anet A8, the controler board does not have a free connector for a Z-Max switch.

What would would be the proper way to install Repetier Firmware with Z-Probing enabled, without this switch? 
I have read as much as I could, and tried, but it seems I am unable to make this work properly, without it. Is there a way to give a Z Max value in a config file, rather than via a switch?

Thanks for your help.


  • You can use the probe as the Z-min switch AND for z probing, no need for a Z-max switch.

  • MartinH said:
    You can use the probe as the Z-min switch AND for z probing, no need for a Z-max switch.

    Thanks, I missed that. I'll check the config file more carefully, then.

  • edited August 2017
    Well, I have spent 2 days searching, redid a full configuration with the online tool, and I am still not getting what I expect!

    I am following this document ( as well as I can, but it looks like, no matter how I look at it, I need a Z-MAX switch in ADDITION to the probe. Problem is, I have no way to add a sensor, my board has no room for it.

    So, questions: Is it possible, YES or NO, to have a proper Z-Probing AND Z-Homing with only a probe?
    If yes, what are, in clear language, the steps and settings to have?

    Here is my current Configuration.H
    Hum, looks like I have problems to attach my file...

  • Yes, it is no problem with dev firmware.

    Most important is to select same pin for z homing and z probing so firmware can detect this special case.

    Then for homing it uses same z probe height for correction, but you might need to set a position to z home since z probes have an offset and need to be above bed. So slect homing sequency with preheat and set preheat temperature to 0. This sequence allows setting a homing position for z homing. Thats all.
  • edited August 2017
    Thank you! I have been able to make this work, finally! One of my mistake was that definition for the matrix points was totally wrong, so each time I was getting an error while doing a G32 measure.

    But now I have another question: I did a G32 measure on a 5 x 5 matrix, and the measurement goes well, I see differences on Z for each point, inside 1 millimeter, even a bit less.

    But If I do G33 L0, I get a list of points, where ALL Z are Z-0.003 !

    So what should I do to see the corrections that are going to be applied? Or, to rephrase it, what am I missing?
  • G32 and G33 are completely different tools.
    G33 L0 lists the result of last G33 run. The 5x5 from G32 are ignored here. Only for measuing the tilt from G32 is used to measure G33 since G33 should only fix the remaining unevenness from bed or delta geometry.
  • Thanks, did not realize that! So, is there a way to see the matrix built by G32?

  • No, G32 does not store the matrix. The points are only used to find the best plane going through all measured points. So for a total planar type only 3 points are necessary. If you have more small errors get averaged giving a better rotation approximation, but more then 4x4 points is pure overkill here for normal beds. Bump mapping is done by G33 where the number of points counts and where you can list them with G33 L0.
  • Thanks, I got it, I have been using G33 at last, and it seems to work well. 
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