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Thread: Concentricity on the thread

  1. #1
    Associate Engineer
    Join Date
    Dec 2017
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    4

    Concentricity on the thread

    can someone help me solve onging discussion wihin Engineering dept. I enclosed the example of Concentricity marked on the thread realted to two smaller diameters located before the thread itself.
    I've been trying to find a standard which expressly explains if its according to GD&T rules.

    1) Is this annotations by the thread correct to the GD&T rules ?

    2)It is possible to measure the minor diameter of the thread and its position to other holes to establish the concentricity, but is it possible somehow to measure the thread concentricity ot it would be enough med minor diameter of the thread ?

    Explanations will be more than appreciated as basically there is a war going on !

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  2. #2
    Technical Fellow Kelly_Bramble's Avatar
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    Feb 2011
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    Bold Springs, GA
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    If the drawing is to the ISO 1101 standard - the Concentricity is interpreted like Position tolerance.

    If the drawing is to the ASME/ANSI standards - it would be an incorrect application. ASME/ANSI Concentricity tolerance is the condition where the median points of all opposed points or surface elements of a feature of size are contained within a circular tolerance boundary defined about the specified datum axis. Which a thread feature cannot be measure to.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

  3. #3
    Principle Engineer
    Join Date
    May 2015
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    217
    You could make a gauge that centers in the 18 mm hole that could measure thread runout.

    I'm not sure how you check the finish on the 15 mm back bore.

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