Runout, roundnes and concentricity

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  • Runout, roundnes and concentricity

    I have a dumb machinist who doesn't know the difference. I've tried to explain ni lock. Can you guys come up with a simple term explanantion so I can just show him the paper!

    I have concen. callout from one id to another, he took an indicator on the machine rotate the part and shoed it to me. I can't deal with him anymore.

  • #2
    Originally posted by MIKEY View Post
    I have a dumb machinist who doesn't know the difference. I've tried to explain ni lock. Can you guys come up with a simple term explanantion so I can just show him the paper!

    I have concen. callout from one id to another, he took an indicator on the machine rotate the part and shoed it to me. I can't deal with him anymore.
    spin on one indicate off the other sounds like that is what he is doing- If he has a good set-up concen will be as accurate as the spindle bearings
    sigpic

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    • #3
      Originally posted by MIKEY View Post
      I have a dumb machinist who doesn't know the difference. I've tried to explain ni lock. Can you guys come up with a simple term explanantion so I can just show him the paper!

      I have concen. callout from one id to another, he took an indicator on the machine rotate the part and shoed it to me. I can't deal with him anymore.
      If that is the way he wants to check it then tell him he needs 2 indicators 180º apart to compensate for any out of round condition.

      edit: If he chucked on a different dia. then he needs 4 indicators.
      Last edited by lambo; 08-15-2008, 03:07 PM.

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      • #4
        thta doesn't help, he is a moron!

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        • #5
          Originally posted by MIKEY View Post
          thta doesn't help, he is a moron!
          Sorry Mickey.
          If that doesn't help nothing will. You said it he's a moron. Guys like that I just walk away and say "that is my reading you have to proove me wrong!".
          If he's not happy with that then screw him tell him to go see his boss unless you are working in a job shop then may God help you.lol

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          • #6
            the problem is hi BOSS i just like him a moron, he don't know the difference either

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            • #7
              When everything is good, they angry that iam not checking everythin on CMM, when sometging is bad they tell me CMM is bad, junk. They tell me I hve to prove it to them not the other way around

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              • #8
                OK, let’s make it short and simple.
                Concentricity is the distance between axis of datum feature and axis of considered feature multiply by two excluding considered feature shape (roundness) and size (RFS).
                Hope that helps

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                • #9
                  Originally posted by MIKEY View Post
                  I have a dumb machinist who doesn't know the difference. I've tried to explain ni lock. Can you guys come up with a simple term explanantion so I can just show him the paper!

                  I have concen. callout from one id to another, he took an indicator on the machine rotate the part and shoed it to me. I can't deal with him anymore.

                  Concentricity

                  the quality of having the same center (as circles inside one another )

                  Roundness–adjective
                  1. ring-shaped, as a hoop.
                  2. curved like part of a circle, as an outline.
                  3. having a circular cross section, as a cylinder; cylindrical.
                  4. free from angularity; consisting of full, curved lines or shapes, as handwriting or parts of the body.
                  5. brought to completeness or perfection.

                  Runount

                  The composite deviation from the desired form of a part suface of revolution through on full rotation of the part on a datum axis.

                  We always desribed Runout or Total Runout as the concentricity down the full length of a cylinder. Anyway... ...I hope this helps.
                  sigpic:cool:Out of This World:cool:


                  Windows XP; PC-DMIS 4.2MR1; One year tucked away.

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                  • #10
                    IT'S all good, but did I mentioned that he is DUMB. I need simpler terms

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                    • #11
                      Originally posted by MIKEY View Post
                      IT'S all good, but did I mentioned that he is DUMB. I need simpler terms
                      C'mon Mickey.
                      It can't be any simplier than the one I just gave ya.
                      If the guy still doesn't get it, the rock would get jealous of calling him dumb.lol
                      Last edited by lambo; 08-15-2008, 04:57 PM.

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                      • #12
                        Roundness

                        Roundness applies to each cross-section separately on a cylinder surface in a round feature, e.g. in a hole or on a shaft. By means of the roundness tolerance, the radius variation for the form of the cross-section is restricted.

                        Definition of roundness

                        In each cross-section, the outline shall be contained between two concentric circles a distance t apart.


                        Coaxiality / Concentricity

                        These tolerances are special cases of position when the tolerance applies to the centre point or axis of a hole or a shaft and the theoretically exact position coincides with the datum or the extension of the datum.

                        Definition of coaxiality

                        The axis shall be contained within a cylinder of diameter t. The axis of this cylinder coincides with the axis of the datum.


                        Coaxiality is used when two cylinders are to be in line with each other and where one constitutes datum for the other. It should be noted that the tolerance applies to the axis of the abstract feature and not to the actual cylinder surface. This is what distinguishes coaxiality from radial run-out.

                        Definition of concentricity

                        The point shall be contained within a circle of diameter t. The centre point of this circle coincides with the centre point of the datum.


                        In principle, concentricity is the same as coaxiality but is used when the tolerance applies to the centre point of a cross-section and not to an entire axis. If what you measure is a cross-section, the tolerance zone will be a circle instead of a cylinder.

                        Circular run-out (radial)

                        The run-out tolerances are a type of “mixed tolerances” where different types of deviations are limited by one and the same requirement. They can be divided into run-out in the radial orientation and run-out in the axial orientation. Both of these types can be divided into circular runout and total runout respectively. The difference between circular and total runout tolerances is that circular runout tolerances only apply to each cross-section separately while total runout is measured over the entire feature.

                        Runout tolerances are usually applied to parts that rotate around an axis of rotation which
                        constitutes datum and can generally be described as a tolerance for how much a surface may vary during one revolution.

                        Definitions of circular run-out (radial)

                        The outline in any cross-section shall be contained between two concentric circles a distance t apart. The centres of the tolerance circles coincide with the datum.


                        The actual form of the tolerance zone is the same as for roundness. The difference is that at runout, the tolerance zone must be concentric with a datum shaft. At roundness, the tolerance zone may be moved along if the toleranced feature is moved from the centre of the datum. Circular runout (radial) thus sets a limit for out-of-roundness since the appearance of the tolerance zone is the same as for roundness, but it also sets a limit for eccentricity since it must be centred with a datum feature.


                        Phew...
                        PC-DMIS CAD++ 2o16.0

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                        • #13
                          Originally posted by vpt.se View Post
                          Roundness

                          Roundness applies to each cross-section separately on a cylinder surface in a round feature, e.g. in a hole or on a shaft. By means of the roundness tolerance, the radius variation for the form of the cross-section is restricted.

                          Definition of roundness

                          In each cross-section, the outline shall be contained between two concentric circles a distance t apart.


                          Coaxiality / Concentricity

                          These tolerances are special cases of position when the tolerance applies to the centre point or axis of a hole or a shaft and the theoretically exact position coincides with the datum or the extension of the datum.

                          Definition of coaxiality

                          The axis shall be contained within a cylinder of diameter t. The axis of this cylinder coincides with the axis of the datum.


                          Coaxiality is used when two cylinders are to be in line with each other and where one constitutes datum for the other. It should be noted that the tolerance applies to the axis of the abstract feature and not to the actual cylinder surface. This is what distinguishes coaxiality from radial run-out.

                          Definition of concentricity

                          The point shall be contained within a circle of diameter t. The centre point of this circle coincides with the centre point of the datum.


                          In principle, concentricity is the same as coaxiality but is used when the tolerance applies to the centre point of a cross-section and not to an entire axis. If what you measure is a cross-section, the tolerance zone will be a circle instead of a cylinder.

                          Circular run-out (radial)

                          The run-out tolerances are a type of “mixed tolerances” where different types of deviations are limited by one and the same requirement. They can be divided into run-out in the radial orientation and run-out in the axial orientation. Both of these types can be divided into circular runout and total runout respectively. The difference between circular and total runout tolerances is that circular runout tolerances only apply to each cross-section separately while total runout is measured over the entire feature.

                          Runout tolerances are usually applied to parts that rotate around an axis of rotation which
                          constitutes datum and can generally be described as a tolerance for how much a surface may vary during one revolution.

                          Definitions of circular run-out (radial)

                          The outline in any cross-section shall be contained between two concentric circles a distance t apart. The centres of the tolerance circles coincide with the datum.


                          The actual form of the tolerance zone is the same as for roundness. The difference is that at runout, the tolerance zone must be concentric with a datum shaft. At roundness, the tolerance zone may be moved along if the toleranced feature is moved from the centre of the datum. Circular runout (radial) thus sets a limit for out-of-roundness since the appearance of the tolerance zone is the same as for roundness, but it also sets a limit for eccentricity since it must be centred with a datum feature.


                          Phew...
                          Haha! good luck with this one.

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                          • #14
                            hahaha, very funy. He could be right that his parts are good since my relationship is off from probe to probe, but still he is DUMB moth...er

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