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Thread: Measuring tolerance of +/- 0.0003"

  1. #1
    Associate Engineer
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    Nov 2014
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    Measuring tolerance of +/- 0.0003"

    Hi All,

    I am a new member and having difficulties in measuring a cross drilled hole in a shaft. The requirement is to measure a hole with a +/- 0.0003", nominal dia on 0.1883 Any suggestion of how to measure this other than investing in a Air gauging equipment?

    Thanks

  2. #2
    Administrator Kelly Bramble's Avatar
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    I'm not aware of any alternative technology that has the resolution you need.

    How many measurements do you need to make? Can you send the part out to a capable shop?

  3. #3
    Associate Engineer
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    Nov 2014
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    Hi Kelly,

    Its for First Article, means that we will make about 10 parts. The problem with Air gauging method is that you will need a special Air Plug which has a nominal diameter for a specified hole. I doubt any shop will have the same exact dimension as required.

    Thanks.

  4. #4
    Senior Engineer
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    Jan 2014
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    Gauge pins can be used as go/no-go gauges. Even if you have a custom go/no-go gauge made, it is cheaper than air gauging.

    Timelord

  5. #5
    Project Engineer
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    Michigan
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    But with a go/no-go method, wouldn't that physical gage also need tolerance of its own? Using the 10% rule, that means this gage would have a total tolerance of .00006, which might be another problem in itself.

  6. #6
    Associate Engineer
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    First i m confused because the way you have mentioned sizes is kind of non-std (0 before decimal). are these limits in inch or mm?
    .1883" = 4.78 mm i think TRI-O-BORE can be used to measure such size or if u have access to advanced tools like Mic-Trac, having accuracy below 1 micron

  7. #7
    Administrator Kelly Bramble's Avatar
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    Quote Originally Posted by mhk665 View Post
    First i m confused because the way you have mentioned sizes is kind of non-std (0 before decimal). are these limits in inch or mm?
    .1883" = 4.78 mm i think TRI-O-BORE can be used to measure such size or if u have access to advanced tools like Mic-Trac, having accuracy below 1 micron
    Yes, SI (Metric) units are normally illustrated with a leading zero before the decimal and Imperial units (inch) are illustrated without a leading zero before the decimal.

    However, notice that the number was given with a " following.

    " = inch units

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