Homing in Z moves away from switch

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  • December 31, 2016 at 10:29 am #10152
    macgenjason
    Member

    Hi All and thanks in advance.
    I bet this is simple but I am not seeing it.
    I have only one homing switch so far in the Z
    mounted at the top wired in the NC way.

    So it works perfectly but only if I set the $3po to 0.
    This makes my Z moves down to the table in a + direction.
    I want my Z moves to be in the Z- direction from the home switch.
    So when I set the $3po to 1 and execute G28.2 X0 the Z head moves away from the switch.
    I have tried swapping the $ztn and $ztm signs but that did not work.
    $$Dump

    December 31, 2016 at 5:04 pm #10153
    cmcgrath5035
    Moderator

    Reference

    Z axis homes (up) to to Z=0.
    Or perhaps I should say that when Zaxis homes, it moves positive until it hits switch, and that is set to 0.0.

    Not sure why you chose these values
    [ztn] z travel minimum -12.700 mm
    [ztm] z travel maximum 38.100 mm

    If your really want that range for Z, try $ztm=0.0, $ztn = -50.8

    December 31, 2016 at 9:59 pm #10154
    macgenjason
    Member

    Thank you for taking the time to respond.
    After looking again at all the settings I see that I had the zsn zsx swapped.
    And I needed to wire the switch to zmax instead of zmin.
    Love this TinyG. Wicked fun.

    This worked as documented.

    [zsn] z switch min                0 [0=off,1=homing,2=limit,3=limit+homing]
[zsx] z switch max                1 [0=off,1=homing,2=limit,3=limit+homing]
    January 9, 2017 at 10:29 am #10157
    Gaylord
    Member

    Sort of related…I have set up a 3040CNC with a TinyG V8 controller. I use Fusion360 for design. TinyG/Wiki suggested the Z axis limit be installed at the top of travel (Z0). This means all Z moves need to be – (Negative). F360’s post processor commands are all + (Positive). I’m guessing that the top of the work piece needs to be registered, but there doesn’t seem to be any instruction on the best way to do this. Creating the set up and cutting paths appears to work okay. And I did set Z0 to the work piece. But Z just skims over the surface, right path but no cutting. What am I missing? Can someone help me please. Thank you in advance.

    January 9, 2017 at 10:29 pm #10160
    cmcgrath5035
    Moderator

    I am a bit confused – I am not familiar with 360 but many tinyG users use it successfully. Are you sure you are using the correct backend?

    You may also be confusing limits and homing. By design, a Z axis homing cycle moves up (positive) until the switch activates (can be set for homing or homing and limit) and that position is set to Z=0. You are correct that moves into material are in – direction

    Some users jog down to the material surface and set Z=0, many use touch plates or in the case of pwb milling, there is a probe cycle that will find the top layer of the pcb material.

    I’d dig more into your 360 configuration.
    Hopefully someone with 360 expertise will stop by here.

    What CAM solution do you use to send and manage your Gcode?

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