Creating alignments on cylindrical parts

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  • Creating alignments on cylindrical parts

    Alright, I'm getting alot of layout requests for parts that are basically cylindrical in nature. I do not have much experience with parts like this and I am having a hard time deciding what is the best way to align off of them. Obviously the axis of the cylinder is an alignment feature, but what's the best way to utilize that?

    I am attaching a photo of a part that I am laying out. There are no datum callouts on the print. I'm thinking I can use the keyway in the inner diameter to stop the rotation. Can I use the axis of the cylinder as the plane? Create a line from the center diameter and the keyway and then use the center of the diameter again for a point?

    I guess what is through me off is that I have dimensions for features called out along the length of the cylinder, based off the base of the cylinder. If I use the axis of the cylinder as a plane feature, there's no guarantee the planes on the ends are perpendicular to that axis.
    Attached Files

  • #2
    Measure:

    1) The cylinder
    2) The circle (bore)
    3) The key-way
    4) Measure a plane at the base of the cylinder and intersect the bore and base

    Level to the cylinder
    Rotate to the bore-keyway (center to center)
    Set XY origin to the bore
    Set Z origin to the intersection point of the cylinder and the base plane.
    sigpic
    Originally posted by AndersI
    I've got one from September 2006 (bug ticket) which has finally been fixed in 2013.

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    • #3
      Without datums and/or a drawing there are too many different ways to align. Without datums, you are left to try to 'guess' the part function and which way to align.

      All that being said, I'd probably do it like Matt said.

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      • #4
        Lots of cylinders here. What Matt said, (WMS), but with the foot note that often on long parts, constructing a cylinder will not work properly. In that case you can use a 3D line constructed between two circles and level to that. Works just fine. HTH
        sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

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        • #5
          You'll have to use the dimensions on the drawing to determine what the datums are supposed to be.
          matt's method sounded good, but compare his idea to the dimensions.
          Links to my utilities for PCDMIS

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          • #6
            Originally posted by gcunniff View Post
            Alright, I'm getting alot of layout requests for parts that are basically cylindrical in nature. I do not have much experience with parts like this and I am having a hard time deciding what is the best way to align off of them. Obviously the axis of the cylinder is an alignment feature, but what's the best way to utilize that?

            I am attaching a photo of a part that I am laying out. There are no datum callouts on the print. I'm thinking I can use the keyway in the inner diameter to stop the rotation. Can I use the axis of the cylinder as the plane? Create a line from the center diameter and the keyway and then use the center of the diameter again for a point?
            I will measure:
            1. A plane on the block where part is resting.
            2. An ID in the center bore.
            3. Midpoint at keyway.

            Level and Z to plane.
            Rotate X between center bore and keyway.
            Origin X & Y to center bore.
            sigpicIt's corona time!
            737 Xcel Cad++ v2009MR1....SE HABLA ESPAƑOL

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            • #7
              Even there are no datums on the part there is still a specification. ANSI B17.1 governs keyway alignment and tolerance. Check your machinist handbook.
              <internet bumper sticker goes here>

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              • #8
                Originally posted by Goodluck View Post
                Without datums and/or a drawing there are too many different ways to align. Without datums, you are left to try to 'guess' the part function and which way to align.

                All that being said, I'd probably do it like Matt said.
                A new theory is emerging that we Coordinate Metrologists may be qualified to assign datums to parts. That the basis for the New version of Pc-dmis is to use our quality engineering knowledge thoughout the quality enviroment with many different devices. That seems to concour with my belief that now the other inspectors will be relgated to being operators, because of the compexity of v4.2, only the most skilled programmers will be able to use it.
                G
                sigpic

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                • #9
                  Originally posted by Cumofo View Post
                  A new theory is emerging that we Coordinate Metrologists may be qualified to assign datums to parts. That the basis for the New version of Pc-dmis is to use our quality engineering knowledge thoughout the quality enviroment with many different devices. That seems to concour with my belief that now the other inspectors will be relgated to being operators, because of the compexity of v4.2, only the most skilled programmers will be able to use it.
                  G
                  That's interesting...
                  sigpic
                  Xcel 15-20-10 - PFXcel 7-6-5 - Merlin 11-11-7 - Romer Absolute 7525SI
                  PCDMIS 2012
                  Windows Office XP

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