Z endstops and Z probe questions

Having read all I can find on the topic Im still left with many questions.
If I have a Z probe do I need a Z endstop? If not needed is one recommended? I see that a Z MAX endstop is recommended but it would take a long time to go the the Z max and back again so I hope to avoid this.
If I fit a Z MIN endstop should this be set to nozzle-bed touch height.

If I dont have any Z endstops how does the Z zero and what is the safest way to ensure the probe is deployed before any probing action.
For a normal print (without z endstops) what is the startup sequence needed when first powered up to print start.

Sorry for so many questions but the penny still has not dropped for me with this.



  • edited May 2016
     dont know what for printer you have but with the command G32 and G29 it wil go to the probing action. G32 homing + probing and G29 only probing. i use only G32 because i want to home first before probing.

    on my printer i have the following 
    z-probe trigger signal >>> z-max endstop pin (5volt and digital pin) (could also be any other digital pin)
    servo motor  >>> x-max endstop pin (5volt, digital pin and ground) (could also be any other digital pin)

    With the probe start script and finished script u can tell the firmware what to run when going into probing. So even before probing actualy happens it wil run the start script first. in my start script i lower the probe first with M340 P0 S500 and when it has done probing, finsished script, i let the probe go up to its original position M340 P0 S0   

    because i have the probe on the z-max i can use m119 it wil show the status of al the endstops and that of the z-probe. dont know when you use a other digital pin than that of the endstops that the m119 gcode still works.

    what i did before i even started was trigger the z-probe and use m119 to see if the status of the z-probe changed, if not than i new i configured it wrong. also i used the m340 gcode like m340 P0 S50 to see if the servo would move 

    hope this helps a bit 

  • Juulius
    Thanks for reply. I still dont know if you are using a separate Z endstop of some sort or just the z probe (wherever it may be connected).
    so a G32 does homing then probing. How is z homed without a dedicated z endstop. If I try a Z home it just goes crashing through the (working) z probe without stopping.

    My printer is my own design, large-ish Cartesian using RAMBo 1.3
  • so you have configured something like this?
    Z homing in negative direction direction (towards min endstop). (Z_HOME_DIR)

    i think that it has something to do with configuring the z probe also as z-endstop that it doesnt like 

    here is my setup, i have a delta bot 

    so i have 3 ensdstops for homing 
    X axis on x-min
    y axis on y-min 
    z axis on z-min 

    my probe z pin z-max 

  • OK so you do have a normal z min endstop.

    My new printer is the first one Iv fitted a z probe to and I thought you could get away without a z endstop .I think I read you can but it seems complex.

    I understand I can add 'probe start script' to lower the probe but I don't think the probe will drop for a z homing.

    Anyway, I thik to get it running I will just fit a z min endstop in the normal way, then experiment with the probe later.

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