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Z travel is going wrong way.


plamelter
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Posted · Z travel is going wrong way.

Hi All,

I built my own printer a while ago, Cartesian with fixed bed. Have printed several items successfully. Used other 3d slicing programs that had cura engines included and they printed fine. So, I wanted to try Cura 3.6 software. Have custom printer profile setup. It homes correctly, but second line of code that says Z15 lower build plate, well that tries to send my hot end through my fixed plate. Not Good.

When using Pronterface, Repeiter, or Craftware they know Z needs to go up , not down. I sure its simple, But so am I  Want something non fiddley Don't want to correct G-code Pre run every time I print..

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    Posted · Z travel is going wrong way.

    So.... The hardware is Ramps 1.4,

    0.9 stepper motors

    DRV8825 drivers

    1.75 E3D Clone

    Bowden tube

    300x300 heated bed

     Marlin 1.3.6

    Linear rails for X and Y

    Z is trapezoid screw x 4

    Looks like a Core XY machine, but X and Y gantry move up from bed.

    Would like to know how to get Cura traveling in right direction,

    As in Z15 should be 15mm above my fixed bed

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    Posted · Z travel is going wrong way.
    On 1/9/2019 at 10:55 PM, plamelter said:

    It homes correctly, but second line of code that says Z15 lower build plate, well that tries to send my hot end through my fixed plate.

     

    Well... the gcode that is generated by the slicer only contains the target coordinates, no moving directions. The comment ("lower build plate") is only valid for printers where the buildplate moves down though... but comments don't matter.

     

    Printers usually don't support negative coordinates, so there is no way to move the z axis "through the buildplate" to a negative coordinate - but your device may be different?

    How does the homing sequence and the calibration of the z-position work e.g.?

     

    If your custom printer needs a different start script: you can modify it in the machine settings (in Cura).

     

    Everything else is a task of the firmware / hardware of your printer.

    If your issue is different - you have to explain a bit more - i guess...?

     

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    Posted · Z travel is going wrong way.

    You need to set up the printer such that Z=0 means the nozzle touches the build plate and Z=10 means the nozzle is 10mm away from the build plate.  Period.  It's okay for the homing position to be at Z=200 if that's what you need to do but it's NOT okay for Z to ever go negative.

     

    Z=10 does NOT specify if something is moving up or down.  It specifies the distance between nozzle and bed.

     

    So Z=20 may be "higher" or "lower" than Z=10.  But Z=20 is definitely "nozzle farther from bed".

     

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    Posted · Z travel is going wrong way.
    On 1/9/2019 at 11:55 PM, plamelter said:

    Hi All,

    I built my own printer a while ago, Cartesian with fixed bed. Have printed several items successfully. Used other 3d slicing programs that had cura engines included and they printed fine. So, I wanted to try Cura 3.6 software. Have custom printer profile setup. It homes correctly, but second line of code that says Z15 lower build plate, well that tries to send my hot end through my fixed plate. Not Good.

    When using Pronterface, Repeiter, or Craftware they know Z needs to go up , not down. I sure its simple, But so am I  Want something non fiddley Don't want to correct G-code Pre run every time I print..

    Hello. im having the same issue. My setup is also ramps but but the bed moves up and down. I put a spring between the end stop so it doesnt break the limiter screw off again and sure enough layer by layer, its going more negative. Prints fine with Slic3r.

    This must be a box to tick to invert or something easy. Help Please!

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    Posted · Z travel is going wrong way.

    There's a discussion about this here that may give you some clues:

     

    https://github.com/Ultimaker/Cura/issues/7630#issuecomment-624543492

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