Alignment of Gear part

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Alignment of Gear part

    Daer all,

    I am new guy for this user forum, currently I am using PC-DMIS in Camio 8.3. (Nikon Make)
    Recently, I found a problem with a alignment issue for my product. It is about a alignment of [ A-B I C I D-E ] of part. Please refer to attached file for details. In that A & B are the circles through which we are going to construct a 3S line as a primary datum, then moving ahead C is plane as a secondary datum and lastly D & E are tooth width, from which we need to construct a line through theirs mid points. As in that I don't understand how to do alignment of this part ?
    Because there are 2 lines and 1 plane. and mostly unluckily axis of 3D line and Plane is same. Its conflicts my alignment. CAMIO is not allowing to add 2 line 1 plane alignment anyway.

    Any help would be greatly appreciated.


    Thank you in advance.

    Best Regards,​​​​​​​
    Atul N
    Attached Files

  • #2
    Maybe...

    A-B as primary (level)
    D-E as secondary (rotation)

    A-B as X,Y origin
    C as Z origin

    Which would give you a [ A-B | D-E | C ] alignment... yes, the order of the datums in the original DRF does not compute.
    PC-DMIS CAD++ 2o18 R2

    Comment


    • atul01011992
      atul01011992 commented
      Editing a comment
      Thanks for your prompt reply.

      I agree on your thoughts. But It is fine if we origin C plane in Z...? Like it is not following 3-2-1 alignment structure(Plane-Line-Point) and also DRF?

      awaiting for your support.

      Thanks

  • #3
    A-B - cylinder, locks two directions and two coordinates
    C - plane, can't lock direction as it's the same as A-B, locks the final coordinate
    D-E - line, locks the final direction (rotation)

    I don't see the problem?

    Code:
    A1         =ALIGNMENT/START,RECALL:STARTUP,LIST=YES
                  ALIGNMENT/LEVEL,ZPLUS,CYL1
                  ALIGNMENT/TRANS,XAXIS,CYL1
                  ALIGNMENT/TRANS,YAXIS,CYL1
                  ALIGNMENT/TRANS,ZAXIS,PLN1
                  ALIGNMENT/ROTATE,XMINUS,TO,LIN1,ABOUT,ZPLUS
                ALIGNMENT/END
    Last edited by AndersI; Yesterday, 04:16 AM.
    AndersI
    SW support - Hexagon Metrology Nordic AB

    Comment


    • atul01011992
      atul01011992 commented
      Editing a comment
      Thanks @andersl for your prompt reply.

      As you said,
      If we lock C plane in Z axis without locking its direction, then how we supposed to lock its rotation after leveling?

      Also for D-E line, how it possible to follow 3-2-1 then?

      I am confused though.

      It would be great if you can suggest idea.

      Thanks

  • #4
    You can't create an alignment that is compatible with the primary, secondary and tertiary datums, because the DRF is wrong. Datum C and A-B is controlling the same rotation...

    A more "correct" DRF would be [ A-B | D-E | C ] instead of [ A-B | C | D-E ].
    PC-DMIS CAD++ 2o18 R2

    Comment


    • VinniUSMC
      VinniUSMC commented
      Editing a comment
      A-B|C|D-E and A-B|D-E|C are exactly the same alignment, in this particular case. A-B in both cases constrains 4 degrees of freedom. C in both cases is only able to constrain 1 DOF, and D-E in both cases is only able to constrain 1 DOF. Changing the order has no effect.

  • #5
    Well, as the datums lock as many degrees of freedom they can (that are not already locked), but no more, I don't see the problem (see my edit above), C is only locking the coordinate. Ninja said the same thing as answer to a duplicate post. There is no law that the datums should be in the order level, rotate, origin - here we have level and part origin, origin, rotate.

    Remember that the C plane should be measured/constructed as "tangent plane, perpendicular to A-B" (I.e. all we need is the Z coordinate of the "high point" of the plane).

    @atul01011992 - it is not a good idea to post the same question in a lot of threads - people will waste their time answering something that has already been answered/discussed elsewhere.
    Last edited by AndersI; Yesterday, 04:34 AM.
    AndersI
    SW support - Hexagon Metrology Nordic AB

    Comment


    • #6
      I'm with Anders - I don't see a problem.


      I don't think it's technically correct in how it's drawn, but in this instance I think the intention is clear.

      I think what's maybe throwing you is it's attempting to show the combined datums (A-B and D-E) as datums in their own right - it's not necessary and just confusing (the A-B in the top left view makes sense, the A-B in the top right view is just wrong.)

      A-B is your primary - Level to this (3D line generated from A and B) and set two origins on in
      C sets the origin in the remaining direction
      Generate / Construct line D-E and rotate to that.

      I'm not clear from your post what software you're using? Is it Camio or PC-Dmis?


      Further to that, I think I understand what your issue is (and what VPT says) but if you follow the Can-May-Must way of thinking it's not a problem.


      If a datum CAN control a degree of freedom, and it MAY (i.e. that degree of freedom hasn't been controlled by a preceding datum) then it MUST.


      In the instance of Datum C, it MAY NOT control the leveling because it's been controlled by a previous datum, it CAN NOT control the rotation (because it's vector is co-linear with the primary datum). Hence it only controls what it can, which is an origin.
      Automettech - Automated Metrology Technology

      Comment


      • #7
        @ vpt.se - Thank you. It does works.
        @ NinjaBadger - Thanks for more clarification (for understanding my concern as well).
        I think it is working on (alignment discussed above like A-B for levelling, D-E for rotation and C for origining at Z).
        Below is the snap of same.
        I am working on CAMIO its version of PC-DMIS.


        @ AndersI - I apologise. I really did not have any intend to do ask repeated question. I joined this forum day before yesterday and I was not known this before. "it is not a good idea to post the same question in a lot of threads - people will waste their time answering something that has already been answered/discussed elsewhere."


        Thanks Ninja , andersl and VPT again.

        Have a great day !
        Attached Files

        Comment


        • #8
          You can do it exactly as the drawing says, just remember that the C plane should be measured/constructed as "tangent plane, perpendicular to A-B" (I.e. all you need is the Z coordinate of the "high point" of the plane).
          AndersI
          SW support - Hexagon Metrology Nordic AB

          Comment


          • atul01011992
            atul01011992 commented
            Editing a comment
            Thank you andersl.

            I will follow same.

        • #9
          Originally posted by atul01011992 View Post
          I think it is working on (alignment discussed above like A-B for levelling, D-E for rotation and C for origining at Z).
          Below is the snap of same.
          I am working on CAMIO its version of PC-DMIS.
          According to the screenshot you are rotating to D-E line which is fine, but you're also setting the Y origin on it.
          A-B should be X,Y origin.

          Camio version of Pc-dmis? I think the CMM was retrofitted from Pc-Dmis to Camio?
          sigpicIt's corona time!
          737 Xcel Cad++ v2009MR1....SE HABLA ESPAÑOL

          Comment


        • #10
          Shouldn't [ A-B | C | D-E ] be [ A-B | D-E | C ] to comply with the 3-2-1 rule?
          PC-DMIS CAD++ 2o18 R2

          Comment


          • VinniUSMC
            VinniUSMC commented
            Editing a comment
            There is no 3-2-1 "rule" that I am aware of.

        • #11
          Is it a rule?
          AndersI
          SW support - Hexagon Metrology Nordic AB

          Comment


          • #12
            Not a rule as far as I was aware.

            A lot of people take it to mean 3 points (plane) 2 points (line) 1 point (point) but was told it actually refers to number of degrees of freedom locked.

            But this in itself is rubbish as I'd consider aligning to a cylinder as the primary datum as a 3-2-1 type alignment, even though leveling and setting origin on a cylinder locks 4 dof.





            Automettech - Automated Metrology Technology

            Comment


            • #13
              Well, if the DRF states [ A-B | C | D-E ] then A-B is primary datum, C secondary and D-E tertiary. Comparing this to the plane-line-point (3-2-1) method, datum C can't be used as rotation (which the secondary datum should control) as it clashes with the primary datum and D-E is a bad choice as a point, these two should swap places in the DRF?

              I feel (from the posts above) that simply disregarding the order of the datums in the DRF is okay, like "these are your datums, use them as you wish"?

              It's my first day back from vacation, so I might be a little more thickheaded than usual...
              PC-DMIS CAD++ 2o18 R2

              Comment


              • AndersI
                AndersI commented
                Editing a comment
                CAN - MAY - MUST is the rule. Not arbitrary selection!

              • NinjaBadger
                NinjaBadger commented
                Editing a comment
                I understand where you're coming from by the way, I'd prefer to see it as you've listed it, but I read that [ A-B | C | D-E ] constrains the DRF exactly the same as [ A-B | D-E | C ].

              • atul01011992
                atul01011992 commented
                Editing a comment
                NinjaBadger - Are you sure [ A-B I C I D-E ] constrains the DRF exactly the same as [ A-B | D-E | C ] ?
                Because C (plane) is not helpful for controlling any of translation except rx, ry & tz, which would already controlled by A-B. (We can origin C in Z but with no axis and D-E is helpful for controlling rz as it is line, we can able to define its axis only if we consider D-E as secondary)

            • #14
              The axis constrains 4 dof.
              plane constrains 1
              line constrains 1

              4-1-1 alignment.

              Alignment must use features in order of constrainments. (Is that a word?)
              AXIS - 4
              then Plane - 1 or Line - 1
              then remaining feature.

              PCDMIS seems to permit either Axis-Line-Plane or Axis-Plane-Line and gives identical results.

              B&S CHAMELEON/PCDMIS CAD++ V2011

              There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

              sigpic

              Comment


              • #15
                3-2-1 Is 1) level, 2) origin, 3) rotate. They teach that in the basic class.
                -Bill

                PC-DMIS 4.2 MR1 - Global Image 7107 - PH10MQ - SP600M

                Comment


                • VinniUSMC
                  VinniUSMC commented
                  Editing a comment
                  That doesn't make any sense. 3-2-1 in reference to level-rotate-origin means minimum 3 features to level, minimum 2 features to rotate, minimum 1 feature to origin (or, analogously, plane-line-point).

                • vpt.se
                  vpt.se commented
                  Editing a comment
                  This is exactly what I mean and with the "features" it can be local points taken on a surface (three points on one plane, two points on another and one point on a third).

                  I think what you guys are trying to tell me is, that the "rule" I spoke of earlier (the order), isn't a rule ("MUST be 3-2-1") but the order might as well be 3-1-2 as long as it is three features/two features/one feature?
                  Last edited by vpt.se; Today, 02:33 AM.

                • AndersI
                  AndersI commented
                  Editing a comment
                  Two cylinders at right angles lock all dof, that would be a 4-2
                  Three spheres lock all dof, that could be a 1-2-3
                  And so on...
              Working...
              X