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Re: Rotary axis offset for XYZAC system

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  • Michael
    Hi Jeff, The offsets for the A & C axes are the distance from the tooltip to the pivot of each respective axis. If your C axis pivot is directly above the
    Message 1 of 4 , Jun 1, 2011
      Hi Jeff, The offsets for the A & C axes are the distance from the tooltip to the pivot of each respective axis. If your C axis pivot is directly above the center of your tooltip when C is at zero, then your offset is 0. The distance from the A axis pivot to the tooltip would be the offset for the A axis. This is because the XYZ coordinates define where the pivot centers will be and the A & C angles specify what direction the tooltip will be pointing. There's a trigonometric function occuring in that post that takes that offset number & uses it as the hypotenuse of the triangle that has as its legs, the X & Y or the X & Z components of the tool position, these X & Y or X & Z components have to be compensated in the X,Y, & Z coordinates of the machine so that the tooltip is surfing your shape.

      I hope that helps.

      --- In CNC_Toolkit@yahoogroups.com, "jialeungmar" <jeff@...> wrote:
      >
      > Hi,
      >
      > In the e-book, it says the offset for axis is for when the cutting tool is mounted on rotary axes. I am trying to generate some test g-code for an application on a 5 axis system with 3 axis on the tool and 2 rotary axis via turn table on a trunnion, which the ebook mentions as XYZAC.
      >
      > In the ebook examples for XYZAC, why are there offsets for the rotary axes? To me, it seems the cutting tool is not mounted on rotary axes. Thanks.
      >
    • jialeungmar
      Hi Mike, Link I roughly drew this diagram of that XYZAC system. I don t think there is a C
      Message 2 of 4 , Jun 1, 2011
        Hi Mike,

        Link <http://imageshack.us/photo/my-images/27/5axismilltrunnion.jpg/>

        I roughly drew this diagram of that XYZAC system. I don't think there
        is a C offset, the C axis offset is not fixed in relation to the tool.
        Is that a valid A offset? Since the A axis is below the tooltip, that
        would be a negative offset, but when I try to set a negative offset, it
        just goes to zero instead. Please let me know what you think. Thanks.

        -Jeff


        --- In CNC_Toolkit@yahoogroups.com, "Michael" <mike@...> wrote:
        >
        > Hi Jeff, The offsets for the A & C axes are the distance from the
        tooltip to the pivot of each respective axis. If your C axis pivot is
        directly above the center of your tooltip when C is at zero, then your
        offset is 0. The distance from the A axis pivot to the tooltip would be
        the offset for the A axis. This is because the XYZ coordinates define
        where the pivot centers will be and the A & C angles specify what
        direction the tooltip will be pointing. There's a trigonometric
        function occuring in that post that takes that offset number & uses it
        as the hypotenuse of the triangle that has as its legs, the X & Y or the
        X & Z components of the tool position, these X & Y or X & Z components
        have to be compensated in the X,Y, & Z coordinates of the machine so
        that the tooltip is surfing your shape.
        >
        > I hope that helps.




        [Non-text portions of this message have been removed]
      • Michael
        Sorry Jeff, I thought you said your machine had a 2 axis head. What you re talking about does not have any offset for the C and as for the A axis, I would
        Message 3 of 4 , Jun 2, 2011
          Sorry Jeff, I thought you said your machine had a 2 axis head. What you're talking about does not have any offset for the C and as for the A axis, I would think you could use a spacer or a block under your material as a sacrificial layer & make a thickness to get zero to be on the A axis pivot, then the offset is zero. Or just in Gmax, set the material so that the A pivot is at that point in the material, then the offset is zero again. Someone else maybe can confirm this thought. Either way, the offset would be zero because the offsets only adjust the position of XYZ to account for the axes being on the head.

          Hope this makes some sense.
          -Mike.


          --- In CNC_Toolkit@yahoogroups.com, "Michael" <mike@...> wrote:
          >
          > Hi Jeff, The offsets for the A & C axes are the distance from the tooltip to the pivot of each respective axis. If your C axis pivot is directly above the center of your tooltip when C is at zero, then your offset is 0. The distance from the A axis pivot to the tooltip would be the offset for the A axis. This is because the XYZ coordinates define where the pivot centers will be and the A & C angles specify what direction the tooltip will be pointing. There's a trigonometric function occuring in that post that takes that offset number & uses it as the hypotenuse of the triangle that has as its legs, the X & Y or the X & Z components of the tool position, these X & Y or X & Z components have to be compensated in the X,Y, & Z coordinates of the machine so that the tooltip is surfing your shape.
          >
          > I hope that helps.
          >
          > --- In CNC_Toolkit@yahoogroups.com, "jialeungmar" <jeff@> wrote:
          > >
          > > Hi,
          > >
          > > In the e-book, it says the offset for axis is for when the cutting tool is mounted on rotary axes. I am trying to generate some test g-code for an application on a 5 axis system with 3 axis on the tool and 2 rotary axis via turn table on a trunnion, which the ebook mentions as XYZAC.
          > >
          > > In the ebook examples for XYZAC, why are there offsets for the rotary axes? To me, it seems the cutting tool is not mounted on rotary axes. Thanks.
          > >
          >
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