hexagon logo
Register Sign in
  • Replies 6 replies
  • Subscribers 221 subscribers
  • Views 66 views
  • Users 0 members are here
Options
Related

Spline pitch diameter as a datum

Flintstone
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.
Attached Files
  • On a conventional CMM, probably not. On a 'spline analyzer' you could create a proper holding fixture that would enable you to perform said evaluations.
  • If the major or minor of the spline is made by the same tool (if shaved), you can use that instead.
    If it was a full broach, you can't do that... technically, unless you KNOW the OD of the broach matches the pitch.

    Otherwise, you can get a mating spline with a shank coaxial to the spline and use it. Put the plug in the spline and measure off the shank. Like those thread things they sell, just a LOT more expensive.

    If this is something you sell to a customer that is going to inspect it, ask that inspector how they do it, and mimic it.
    At least that way you are both getting the same answer.
  • Thanks guys,

    Some of this is kind of what we were already thinking. We actually make this part in house and it's assembled into our own product. Apparently, we haven't been checking runout to A-B, just checking diameters and such. Someone decided to outsource it, and now by our own rules, we are forced to check a sample from the vendor. We did find a go-no gage for the spline, but it won't work to check runout. The vendor sent us results they said they got with a CMM, I'm almost afraid to ask them how they did it. Slight smile This is going to be an adventure.

    Appreciate your help.
  • 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.
  • Not a CMM Job , check on plate using indicators and Gage Blocks or similar.
  • I'd try using a stylus the size of the pin called out to measure pitch diameter, and autofeature vector point with the self centering option. Then construct a circle from those.
© 2024 Hexagon AB and/or its subsidiaries. Privacy Policy | Cloud Services Agreement