IDEAS Dual Z stepper drivers

Discussion in 'Guides, Mods, and Upgrades' started by Stian Indal Haugseth, Jun 3, 2016.

  1. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    I have been thinking about why we do not use the last driver slot in RUMBA to have dual Z stepper drivers.

    It looks like Marlin has support for this but I'm not sure how it will work with the IR endstop on the x carriage. Ideally it would go for center Y and measure one then the other with a slight offset between them so the second doesn't travel too far.

    Serach for Z_DUAL_STEPPER_DRIVERS here: https://github.com/BigBox3D/Marlin-Direct/blob/RC/Marlin/Configuration_adv.h

    Not sure I get what they mean with M666 and software endstops adjustment.

    And I know someone will ask why. I say because I like the concept and want to know more :)
     
  2. Alex9779

    Alex9779 Moderator
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    This feature is just that you use one driver for each motor. Both get the same signals.
    The setting you can then use would be to have an endstop for each Z motor so the firmware can level the bed be driving each motor different.

    I asked @Greg Holloway about why that is active, he just told he is useing this for a side project and is has no real effect if active or not since it is just that Marlin gives two stepper drivers the same signals.
    If you haven't installed a stepper driver on I think E2, didn't check the PIN setup for this yet, or connected both motors to the Z driver it will work anyways...
     
  3. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    I have curious kids and would not be surprised if they will turn the z couplers one day. With dual homing z this would not be a problem :D
     
  4. Alex9779

    Alex9779 Moderator
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    Yeah that may be a factor, but to actually make use of this you have to mount a second endstop. And as the endstop on the BigBox is not fixed (yeah Greg made an alternative part, you can use that) I have no idea how to make this work.
    Regarding the fixed endstops I am not thinking that way, because I am waiting for the auto mesh bed leveling which needs a movable probe, which is currently the endstop.
    An alternative would be to have the Z probe for leveling and two separate endstops for the general homing of the Z axis...
     
  5. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    Yepp. I have the same thoughts. But I cannot help thinking that this could be solved by moving the x carriage to each side and use the IR sensor. But I see the difficulty with one side being to far off. Both z rods would move for the first homing then just the second. But having enough leeway so it doesn't hit the top.
     
  6. Alex9779

    Alex9779 Moderator
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    You are absolutely right.
    A step further would be to use the moving endstop we have to achieve the same thing.
    But unfortunately I think Marlin is not that far at the moment. Though we could make up a feature request for this...
     
  7. Stian Indal Haugseth

    Stian Indal Haugseth Well-Known Member

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    I have now added a stepper driver and controlling Z with two stepper drivers. So now I have Z and Z2.

    Next step will be looking into adding two optical endstops for leveling Z and Z1.

    Ultimate goal: Auto leveling of Z and Z1 then automatic MBL with inductive Z probe.
    IMG_20160808_155113.jpg
     

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