Please help. Z Axis no longer Homes after random crash



  • check the wiring of the endstops. unless they are triggering them at the moment they should show not stopped.



  • I have just moved the axes off the Home position X and Y are not stopped, Z is at max stop:
    Capture M119 #2.PNG



  • Did something get bent or damaged on your Z axis that is preventing it from travelling in both directions?

    If you use G92 Z10 to set the position of the Z axis while it's in a safe location are you able to manually jog the Z axis both up and down?



  • z showing triggerd all the time would explain why you cant home z.

    check the wiring of the endstop with a multimeter.



  • @Phaedrux yes, I can jog in both directions



  • @Veti showing my stupidity here but how should the multimeter respond if the switch is no good/good? Thanks 🙂



  • If you measure for continuity on opposite sides of the switch it should have no continuity if the switch isn't depressed. But it would seem that it has failed as a closed circuit, so your test would show continuity even though the switch isn't being pressed.



  • depends on the switch type.

    set multimeter to ohm.
    connect red and black probe to wires with signal and ground of the endstop

    Normaly open switch.
    infinite when not triggerd.
    some value close to 0 when triggered

    Normally closed switch
    some value close to 0 when nottriggered
    infinite when triggerd.



  • @Phaedrux Ok, thanks! I'll do this as soon as I can and let you know what results I get (most likely tomorrow).



  • @Veti Thanks. I'll let you know how I get on.



  • Ok, so I tested all three limit switches with a multimeter this evening. On both the X and Y switches I get a constant value of 1 when the switches are triggered/depressed. When I release them, I get a variable reading much closer to zero. When I test the Z switch - regardless of whether the switch is open or triggered - the value is a constant 1. Does this indicate that the Z limit switch has failed? I presume so but I have very little/no experience with this kind of thing 😄 The guys who supplied my cnc are shipping out a replacement anyway.



  • @Bags said in Please help. Z Axis no longer Homes after random crash:

    Does this indicate that the Z limit switch has failed?

    it could be the switch has failed, or the wiring to the switch.
    see if you can connect the probes to some exposed metal on the endstop itself where the wires go in and test again



  • @Veti Thanks. I will try although it is fixed in an extremely difficult place to access.



  • @Bags
    well you have to take it out anyway to replace it if its broken.
    this might give you a chance to fix it yourself and be ready before the replacement arrives.


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