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DRO Scale parallelism

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  • DRO Scale parallelism

    I am mounting the x and y scales on my mill and the installation manual is barely readable It says to make sure
    the scales are mounted parallel to the table. I put an indicator on the x axis scale that is bolted to the front of the
    table and I get about -.001" on the ends and 0 in the middle of table travel. Is that good enough ? The ends are
    bolted to the table so I guess that's why I have a bulge in the middle ???

    Also I ran an indcator on top of the x axis scale and have about +/- .002"
    along the length of the scale. The table is 32" long with about 22" travel on x.

    Are these OK or do I need to get more parallel ? It is a Sino Glass Scale DRO.


  • #2
    Dro = Ok

    An error or 0.001" per inch in parallelism gives a potential error of the DRO reading of 0.0000005" which is so close to zero that it doesn't matter as the accuracy of most/many DRO's is +/- 0.0002".

    But that said, there may be mechanical reasons within the DRO that require as good as you can reasonably get.

    I'd say that your set-up is OK.


    • #3
      The Accurite manual and the Mitutoyo manual I have both say +/-.0025"IIRC.The reader heads do have some float,just not much.

      Did you run a file or oil stone across the surface they are mounted too before installing? Sometimes the least little ding or nick will throw things off that much.
      I just need one more tool,just one!


      • #4
        If the brackets have any provision for adjustment, you could tighten them only slightly and run the table back and forth as you continue to tighten. That should automatically align them.

        If not, I would try for +/- 0.001 or better.

        I am doing the same thing at the present time. I am using a 6" and an 8" caliper with a 24" Grizzly scale on mine. Have to make my own brackets for the calipers.
        Paul A.
        SE Texas

        Make it fit.
        You can't win and there is a penalty for trying!