Eval of a circle and correlation

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  • Eval of a circle and correlation

    Hi guys. What do you think realistic data would look like when you trying to corrolate a ring gage using two different cmm’s @ different locations?

    i know, i know, a lot can go wrong here, but if we take the exact same type of high precision CMMs with exact same programs and measure the inside diameter 3.5000 “ what would you expect to see? Of course temp. Will vary from lab to lab.

    from my personal experience when dealing with two different CMMs the LS or Max inscribed results can range up to .0002 or so. In your experience Is it possible to correlate with in .00005 or less?? Thoughts?

    i am asking if anyone has tried anything like this before and what results looked like.
    Last edited by WolfMan; 08-30-2019, 05:37 PM.
    B&S One
    PC-DMIS CAD v2014

    Romer Infinity

  • #2
    If you truly have a high precision CMM(PMM) you should correlate within .00005", but you should have both in a stable environment.
    If you simply have a very good CMM, e.g. a new Global Advantage, you should correlate within .0001". Again you need to be in stable environments.
    PC-DMIS 2016.0 SP8

    Jeff

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    • WolfMan
      WolfMan commented
      Editing a comment
      Would you say +/- 1 degree is stable?

    • WolfMan
      WolfMan commented
      Editing a comment
      Using Zeiss with Vast XT gold head. I am assuming since i am measuring a diameter, its all about the repeatability of the probe, and linear accuracy doesn’t matter much.

  • #3
    That's a step up from Global Advantage, but not quite in the PMM range. You would need to be linearly accurate for the distance of 3.5"
    If you have two Zeiss CMMs in ±1° F enviroments, they should correlate within less than .0001" for a 3.5" ring gage I believe.
    PC-DMIS 2016.0 SP8

    Jeff

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    • WolfMan
      WolfMan commented
      Editing a comment
      What other gages can be used in order to correlate with in .00005, besides an air gage? Air gage seems to scratch the ID and was hoping to find a gage other than CMM to measure something like that.

    • WolfMan
      WolfMan commented
      Editing a comment
      Would you say that the Max inscribed circle would produce more repeatable results than the LS?

    • RIDER
      RIDER commented
      Editing a comment
      Pratt & Whitney LabMaster or SuperMic are both repeatable in the millionths.

  • #4
    Rider, how about an iD?
    B&S One
    PC-DMIS CAD v2014

    Romer Infinity

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  • #5
    Thanks Rider. Good stuff.
    B&S One
    PC-DMIS CAD v2014

    Romer Infinity

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    • #6
      You should explain a little more what you want and what you do.
      First, is the same ring gauge, or not ?
      What about the uncertainty of the ring gauge calibration (diameter and form) ?
      Then, how do you measure it (vertically or horizontally) ?
      Do you measure it point to point or by scanning ?
      Do you measure the ring gauge at different locations on the same cmm ?
      What is the tolerance of the cmm on 90 mm (3.5"... ) ? for example, a PMM12 10 7 with U= 0.5+L/600 gives .75µm, so 0.00003" of tol.

      Sorry, I've no answer, only questions...

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      • WolfMan
        WolfMan commented
        Editing a comment
        I know Jeffman. I understand that it’s not that simple.

    • #7
      What material is the ring gage? Different materials will have wildly different variations due to temperature.

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