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Thread: Bolt circle pattern w.r.t datym

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    Bolt circle pattern w.r.t datym

    Hello highly skilled engineers. I am trying to clock and center a flange to a crankshaft w.r.t. a feature on the crankshaft. How do I cajole that sentence in to this new language?

    I have a primary datum as the face of the crank, secondary datum as the centering counterbore, and a tertiary on a crankpin on the axis.

    1 Do i apply RFS rules?
    2 How do I ensure bolt hole mating pattern gives me enough clearance to let the boss do the centering, as well as the dowel pin to give me precise angular orientation wrt to a crankpin?


    I am trying to do something Similar to page 6 of this 1980's on crankshaft re-drawing.

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    Technical Fellow Kelly_Bramble's Avatar
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    cranksahft.PNG

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    Last edited by ggucci3; 04-06-2022 at 11:35 PM.

  4. #4
    Technical Fellow Kelly_Bramble's Avatar
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    Quote Originally Posted by ggucci3 View Post
    Hello highly skilled engineers. I am trying to clock and center a flange to a crankshaft w.r.t. a feature on the crankshaft. How do I cajole that sentence in to this new language?

    I have a primary datum as the face of the crank, secondary datum as the centering counterbore, and a tertiary on a crankpin on the axis.

    1 Do i apply RFS rules?
    2 How do I ensure bolt hole mating pattern gives me enough clearance to let the boss do the centering, as well as the dowel pin to give me precise angular orientation wrt to a crankpin?


    I am trying to do something Similar to page 6 of this 1980's on crankshaft re-drawing.
    The datum reference frame defined in the attached crankshaft image is not typically used with modern crankshaft. I would suggest that the method is an academic example.

    Typically, crankshaft DRF's are specified with the primary datum being the main journals collectively (A-B-C-D) and the secondary datum being the harmonic balancer orientation feature (keyslot) or one of the piston journals though a clock hole on the crankshaft bolt pattern can be used.

    'Hello highly skilled engineers. I am trying to clock and center a flange to a crankshaft w.r.t. a feature on the crankshaft. How do I cajole that sentence in to this new language?" It already is with the DRF specified, Datum feature "C' is the clocking feature.

    "Do i apply RFS rules?" If utilizing ASME Y14.5-2018 - nothing as the absence of a modifier on a datum indicates RFS.

    "How do I ensure bolt hole mating pattern gives me enough clearance to let the boss do the centering, as well as the dowel pin to give me precise angular orientation wrt to a crankpin?" You'll need to do the math and assign tolerances for the type of fits required to achieve the functional mating and alignments you require. This cannot be answered with an extensive discussion on tolerance analysis as well as limits and fits.
    Tell me and I forget. Teach me and I remember. Involve me and I learn.

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