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Spline pitch diameter as a datum

Good morning,

We've been asked to measure runout of a hub flange, and position of holes in the hub to A-B. A is a bore at one end of the hub, and B is, it looks like anyway, the pitch diameter of an internal spline. The pitch diameter is 47.625 mm and the spline is situated inside of a tube with a clearance diameter of 59 mm. We are using a global machine, and our soft ware is PCDMIS 2021. We don't think we can do it. We're going to ask engineering if we can use the minor diameter of the spline instead. We thought we'd run it by the big brains, just in case someone has a better idea.

Thanks.

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  • Hahaha I recognize that part!! At night, I double as a spline gage and master gear designer / salesman / inspector.
    Forget the CMM, you're wasting your time and you're going to get erroneous results.
    I would say right up front, based on the feel I get on your description, yeah, you probably don't want to mess with this. At a minimum you'll need a tapered spline arbor to capture the "PD" of the internal spline for one. You cannot use the minor because that is completely independent of the spline itself (they are cut at different times with different tools). You would get the part dialed in with indicators, that spline arbor, and use a height stand to get your hole deviations. Tapered spline arbor for that size runs about $2300 direct form the source if you know where to go.
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  • Hahaha I recognize that part!! At night, I double as a spline gage and master gear designer / salesman / inspector.
    Forget the CMM, you're wasting your time and you're going to get erroneous results.
    I would say right up front, based on the feel I get on your description, yeah, you probably don't want to mess with this. At a minimum you'll need a tapered spline arbor to capture the "PD" of the internal spline for one. You cannot use the minor because that is completely independent of the spline itself (they are cut at different times with different tools). You would get the part dialed in with indicators, that spline arbor, and use a height stand to get your hole deviations. Tapered spline arbor for that size runs about $2300 direct form the source if you know where to go.
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