Middle Assembly / Z Wobble

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This topic contains 4 replies, has 2 voices, and was last updated by Profile photo of Ryan Ryan 3 weeks, 3 days ago.

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  • #32896
    Profile photo of Kris
    Kris
    Participant

    MPCNC question for you all… I noticed yesterday that I have some play in my middle assembly. If I grab the z at the top by the stepper and the bottom and push/pull I get wobble – or whatever the correct term is….. I am thinking I should not be able to do this and not sure how I solve for it.

    Thoughts?

    #32898
    Profile photo of Ryan
    Ryan
    Keymaster

    How long is your z axis? How long are your X and Y axes?

    Is it moving exactly up and down (backlash), or like you can bend it?

    #32899
    Profile photo of Kris
    Kris
    Participant

    These were the tube measurements:

    PCs Inch Description
    3 35.4 1 od x .049w 304 s.s.weld tube A269
    3 29.4 1 od x .049w 304 s.s.weld tube A269
    2 12.5 1 od x .049w 304 s.s.weld tube A269
    4 4.5 1 od x .049w 304 s.s.weld tube A269

    Not really up and down.. more so back and forth pivot.. maybe I can try to shoot a video show what I am talking about.

    It’s cutting ok but just not sure if I should be concerned about it or not.

    #32901
    Profile photo of Ryan
    Ryan
    Keymaster

    Cutting is kind of all that matters?

    This is exactly why I say not to attach things on the z axis motor mounts. It is a torque multiplier, with a linear increase. Any force on the top translates directly to the bottom. half the length 2 times the rigidity, every single mm matters. So you shaking it is like using a breaker bar on the lug nuts of your car, instead try and move it from the very tip of your cutting bit, this is all we care about. For every half the distance to the carriage it will be two times harder to move the bit.

    #32902
    Profile photo of Ryan
    Ryan
    Keymaster

    Plus a little extra for your x and y flex, but it should be minimal even though those are kinda long axes.

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