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What kind of rods are used as X-axis

Discussion in 'Requests and Suggestions' started by polylac, Aug 17, 2014.

  1. polylac

    polylac New Member

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    I ask because I'm thinking about upgrading my Printer and doing some research and found out that for a linear motion a hardened rod should be used, when using ball bearings.
    I looked at the robo X-axis and saw a lot of scratches on the surface.
    The Diameter seems also a bit to much under 8mm (I guess they should be 8mm) about 7.9 to 7.95. *Edit maybe i just measured not so exactly the first time, now i get 7.98 to 8.00, so I'm not so sure)*
    The sledge (the thing that holds the ball bearings with the print head) also has a lot of backlash (moves around while the belt is not moving).

    Does anyone know something about this?
     
    #1 polylac, Aug 17, 2014
    Last edited by a moderator: Aug 17, 2014
  2. Kevyn Watkins

    Kevyn Watkins New Member

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    Yes, hardened steel, precision ground rods are what you are chasing. Replace your bearings at the same time. Robo's ship with cheap steel rods, which helps keep them at an entry level price point.

    As for your X Carriage slop, have you tensioned the belt?
     
  3. polylac

    polylac New Member

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    thank your for the information

    it's not from the belt, the belt is tensioned, its the carriage that moves on one side if i push it a bit from left to right, about 0.4mm (the nozzle will move about the halv amount of that).
    but the reason is now clear, they use cheap rods an bearings which have a bigger tolerance so they allow a bit more movement than one would wish.
     
  4. Mike Kelly

    Mike Kelly Volunteer

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    The rods on the robo 3d are all 5/16 aka .3125", not 8mm (.315in)
     
    #4 Mike Kelly, Aug 17, 2014
    Last edited by a moderator: Aug 17, 2014
  5. polylac

    polylac New Member

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    So they should be 7.94mm, seems like my first measurement was not that much wrong...
     
  6. polylac

    polylac New Member

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    hi again, a bit strange that they use LM8UU linear barings, when they don't use metric rods...
     
  7. Mike Kelly

    Mike Kelly Volunteer

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    2.5 thou isn't exactly a detrimental amount of slop. But yes, it's kinda disappointing.
     

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