GD&T Question

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  • GD&T Question

    How do I use the basic [4.39] with total run-out or do I somehow add it with the concentricity? I am lost with how to measure the 4.39". I can do it with a true position but that is not an option here.

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  • #2
    One thing is for certain the 4.39 has nothing to do with the total runout callout or concentricity. The total runout is to A only same with concentricity.

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    • #3
      I would assume that, on the right side image, the right end of the part should be a datum - let's call it B. Position of radial groove to B should be specified to control that 4.39 dimension.

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      • JGRIFFIN
        JGRIFFIN commented
        Editing a comment
        incomplete print. Unless there is something up in the notes like a profile to tolerance it.
        Last edited by JGRIFFIN; 12-04-2019, 08:35 AM.

    • #4
      I don't know about ISO world but the drawing is non-compliant per Y14.5. Datum A is a planar feature. You need an axis about which to rotate to evaluate the total runout. I would kick this one back to the customer.
      153010 Global Advantage w/ LSPX1H_T Analog Probe
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      • RIDER
        RIDER commented
        Editing a comment
        How is it cylindrical? The black triangle is resting on a planar surface. What am i missing here VinniUSMC?

      • VinniUSMC
        VinniUSMC commented
        Editing a comment
        Well, what does a cylinder look like when you look at it from the side? Look at the view on the left. Everything is concentric circles. If it's not a cylinder, I'd be very surprised. And, the view on the left is looking at the part from the smaller end (Datum A is facing us in the view on the left.)

      • Rich P
        Rich P commented
        Editing a comment
        There is an extension line coming off the cylinder, looks like A is pulled off of that surface
        Poor drawing but only way that concentricity to A makes sense to that FCF but confusing and not sure legal because it is on surface extension not diametrical
        Total run out to A then makes no sense to surface that is pointing to

        Very poor drawing

    • #5
      That 4.39 is only useful if there is a Profile callout for that groove, and the far right end of the part is a datum. Or it could be a gage circle location, but then there should be a size or other dimension associated with that also. If there is no other dimension for that groove somewhere else, then the 4.39 is meaningless.
      "This is my word... and as such is beyond contestation."

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      • #6
        Thank you all for the replies, I will try to get this print updated to reflect the current Y14.5 standard.

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        • #7
          I have been informed today that "Basic dimensions can be used with profile, position, and runout too." I was asked to review some books.
          Last edited by Zeros; 12-11-2019, 10:40 PM.

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          • JacobCheverie
            JacobCheverie commented
            Editing a comment
            Your 4.39 BASIC is tied back to the right hand side, where there is no datum. As already stated here, unless there is something stated in a note or on the print elsewhere, that basic dim should be connected to a datum feature with a corresponding geometric control somewhere on the print. The statement that you were given "Basic dimensions can be used..." is an attempt to circumvent the issue that this print is incomplete as we have been presented it here.

            As kingsld says, there is also nothing wrong with enhancing your GD&T knowledge on company time.

          • CMM_ENG21
            CMM_ENG21 commented
            Editing a comment
            Zero,
            BASIC dimensions almost always correlate back to a feature control frame....so things like "profile", "position",and "runout" are directly related to BASICS if the engineer knows what he/she is doing....rough example FEATURE CONTROL FRAME: POS|Ø.015|A ....this roughly correlates to ±.0053 So if you have a basic relating to a specific feature connecting any 2 axis' the tolerance on both would roughly be ±.0053..this works for hole locations....profile if it is bilateral...example profile( bilateral) of .020 ....means ±.010 ....runout is found using dial indicator usually ......when checking runout the most accurate way is with a dial indicator with proper graduations...i.e.; .001 or .0005, or .0001...etc....

        • #8
          Originally posted by Zeros View Post
          I have been informed today that "Basic dimensions can be used with profile, position, and runout too." I was also instructed to review some books. How do I answer this without causing further animosity?
          Agree that Basics can be used with profile and position. Make at least semi serious effort at reviewing the books. Then ask to be shown where that information came from. Worst that could happen is that your g,d & t knowledge can be expanded on company time

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          • #9
            Ask them to show you how that 4.39 basic relates the feature to A.

            Imagineers... Making sh** up as they go.
            "This is my word... and as such is beyond contestation."

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            • #10
              Originally posted by Zeros View Post
              "Basic dimensions can be used with profile, position, and runout too."
              Wait, what?

              Sure, it can be used on a drawing having both basic dimensions and GD&T, but basic dimensions (TED) - as far as I know - does not control runout (i.e. you do not need basics to check runout - unless at a specific position on the feature).

              I might be stepping out on a limb here.
              Last edited by vpt.se; 12-10-2019, 11:25 AM.
              PC-DMIS CAD++ 2o19 R1 SP5

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              • #11
                Thank you all for your support, this issue has been advanced to a higher-ranking individual. Fingers crossed this gets fixed moving forward.

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