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DRO loosing position

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  • DRO loosing position

    I'm curious. Do some DROs loose position when vibration caused by insufficient rigidity causes the table to vibrate. I believe all the DROs have specification on maximum travel speed, but nothing about vibration that will fail the tracking.

    In other words, does the DRO reading ever drifting in on direction when really it's just vibrating at a high frequency and not moving.


    [This message has been edited by Rotate (edited 04-23-2002).]

  • #2
    Biggest problem is making sure you loctite everything properly. Barring a failed electrical connection, loss of back up power for the readout units memory (capacitor backup, i.e. 1F 5.5v), or total failure of the scale it should never turn up.

    [This message has been edited by Thrud (edited 04-24-2002).]


    • #3
      I believe the display on commercial units are averaged so no flutter is displayed at lower resolutions. When more (in)significant digits are used the flutter would show up at the tail end like in digital meters.

      [This message has been edited by Thrud (edited 04-24-2002).]


      • #4
        When I get my cheapy DRO's I was planning on mounting them between squeegee rubber using two plates. Blue Loctite on all screws. Bond one plate if I have to. Use the data outputs to feed the signal to a PIC micro. Love them PIC's. Software will use a rolling buffer which is basically a low pass filter.This should take out flutter, I hope. I will have to see when they arrive next week


        • #5
          Most common probllems with dro's is guys blowing chips in the scales with compressed air, or not having limit switches set right and too short a scale.

          Keep your air blast away from the ways slides and dro scales.

          Don't depend on limit switches, they WILL fail sooner or later.

          Air dosen't clean anything, it just relocates it somewhere else. The floor, your eye, hair, inside machine components.

          I mounted one on a shear backgage once for a guy (d.r.o).
          That dro lost position every time the machine cycled.



          • #6
            metal mite:
            Mitutoyo ABS capacitive scales are used on production woodworking gear with success.

            Shears have a great deal of physical shock - especially large plate shears. They are an extreme example - most shear have a mechanical DRO.


            • #7
              I haven't heard of this particular problem with dro's. You would have to check the specs of the scale to see what the tolerance on alignment is. If the maschine is in fact moving at all. I had to refuse a job mounting some scales on presses because the machine moved more than the specs of the scale allowed. A problem could be that the cable from the head has been stressed and you are getting noise from poor grounding.