Position with only 1 basic dimension

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  • Position with only 1 basic dimension

    This will really sound like an elementary question but here it is anyway... I'm trying to "prove" that a position using only 1 basic dimension is simply 2X the deviation in that given axis. They don't believe me. The engineers can't find a formula for that particular equation (because it would be stupid to even go through the exercise...) 2x sqrt of X^2 will always = the deviation X2 so they're freaking out. They've got to have "proof"

    Anyway, can you guys (and gals) point me in the direction where I might be able to find an explanation for this type of position? The guys upstairs thing that the total deviation is the position when in fact it is not. That is just a stupid linear distance and nothing more. I need something to "prove" this to them since evidently I'm to stupid for them to believe what I tell them... I'd really appreciate it any help. Thanks in advance.

    Mike

  • #2
    Tell them Craig from Elmira said they are idiots and to call me if they need to hear it from the horse's mouth (yeh I'll give you my #). Looks like we have a winner for the pet peeve contest in the off-topic side and it is engineers, or should I say looser? Any way you are right, explain it in terms of target zone. If they still don't get it I'm serious about the phone # thing PM me with a number I can call them at and put it on speaker phone. I feel bad for you man, I'm sorry those people are breathing your air right now. Would heart punching one of them be an option?

    Craig
    <internet bumper sticker goes here>

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    • #3
      Well, in two dimensions the position is calculated using the pythagorean theorem x^2+y^2=z^2. Substitute zero for y^2 and you get x^2=Z^2! Simple geometry.

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      • #4
        explain it as a slot ,one direction or axis
        DR Watson shut me down again !!!! :mad: Smoke break:eek:

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        • #5
          You don't need to look up a new formula use it just as you would with 2 axis just input "0" for the other one.

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          • #6
            The reason you double the deviation is because the T.P. tolerance zone is Diametrical. What you have with the deviation of the 1 axis is the Rad of that Diametrical tolerance zone.
            Badges..... We don't need no stinkin badges.

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            • #7
              True Pos.

              I agree with Sean, thats what were calculating True Pos
              in one direction here.

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              • #8
                This may be somewhat helpful...

                http://www.bitsworkshop.org/archive/...ot%20gd%26t%22
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                • #9
                  Position with a Square Symbol? Measuring Position on Square Features?

                  I took a few GD&T courses at the Chrysler Technology Center (C.T.C.) with this guy. He is on the ASME commitee and has written several books on GD&T over the years. Look at "Position with a Square Symbol? Measuring Position on Square Features?" on this link. It may also help explain the single axis position dilemna...http://www.geotolmeadows.com/newslet.../april2005.htm
                  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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                  • #10
                    Good site Ranger thanks
                    sigpic
                    if you had soap on a rope it would be tied to yer ankle

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                    • #11
                      Mike,
                      One thing that I find helpful in explaining the results is: "Just what is the results telling us?"
                      Try explaining that - what you see is the tolerance zone it would take to encompass said feature. Being that you have a "bi-directional" position requirement - the tolerance zone shown in your report (the TP results) will grow, or shrink depending on the feature (Each side of the zone), hence the deviation x's 2. You are showing just what size tolerance zone it takes to make the feature "good" - and then relating that result back to your drawing specification(s). 1 side of the tolerance cannot move independatly. They move together.

                      Remember to also explain: That basic dimensions locate the tolerance zone, and the tolerance zone is in equal distrabution about the theoretical center (located by those basic dimensions).

                      It's along the same lines of profile of a surface....

                      Kev
                      RFS Means Really Fussy Stuff

                      When all you have is a hammer - everything looks like a nail....
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                      • #12
                        You guys have been a big help. Thanks for all of your input and thanks for the links to some great information. I really appreciate your feedback. It's nice to get advice here because when I go talk to them today I feel as though I now have backup. Thanks!

                        Mike

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                        • #13
                          A very simple excell calculator

                          This is an easy way to quickly demonstrate what your folks are having trouble with.

                          Last edited by John Riggins; 08-24-2007, 01:52 PM.
                          Lately, it occurs to me
                          What a long, strange trip it's been.

                          2017 R1 (Offline programming)

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                          • #14
                            A basic dimension??

                            Basic, as in established to be correct?

                            Therefore, the deviations on the remaining axes, used in a positional calculation are the key.

                            BTW, are you working on the axial position reactional makeupathinginator from the space station?

                            Numbers are our friends, that doesn't make us enemies.
                            -Baggy


                            http://baggy3.info/signani3.gif
                            http://baggy3.info/signani3.gif
                            Excercise your mind,..... muscle works better than fat!!

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                            • #15
                              There is a symbol used to indicate two axis POS as opposed to one Axis POS. It has always been called the Diametric symbol as far as I know - that's what everyone I know call it. Without it the POS is the same as a Linear Dimension and basically plus and minus hals the positional tolerance. Engineers should know this as THEY are the ones who put it on the print in the first place. LOL

                              Bill
                              Bill Jarrells
                              A lie can travel half way around the world while the truth is putting on its shoes. - Mark Twain

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