Novice ? about true position tolerance

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  • Novice ? about true position tolerance

    We are using Pcdmis 3.5
    Most prints callout true position as total tolerance eg. .01
    The dimensioning window for tp asks for + and - tolerance.
    Should we enter +/-.005 or +/-.01?
    Also, does the "display as radius check box affect this?

  • #2
    Use the drop down and select TP, then just enter the .010 in the plus tolerance area.

    HTH
    Mark Farren

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    • #3
      In the true position window do not select either. Pick your features then create your true position. Then in the edit window tab over to the tolerance location next to the TP and enter in .010
      Time for the Trolls to leave.

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      • #4
        Don't let the menu overwhelm you. You've been given the keys to a fighter jet with all the bells and whistles and you'll find that half of the time you just need a lift down the street. First off, Is your T.P., say relative to datum axes?
        Like say a hole from some edges? Let's keep this simple.

        If you say for example have a hole located from datum axes (controlled by basics I assume), then let's start at the tolerancing pulldown. You can set your tolerances for every d*mn thing you need right here. For the TP, just put in your total tolerance as "plus." TP has no negative tolerance, it's just a number based on an equation set up by your "actuals" vs "basics or theorheticals." The diameters of your measured feature as well as any mmc features can also be established here as well. You also have mmc and rfs modifier menu callups as well. Here you can add in any mmc tolerance allowed by your print callout by defining other features already measured. You must be sure to click on the measured feature as you call them in for mmc. As far as your deviation menu, it too is a specialized tool. The radial callout if checked will allow you to display your diametric features & datums (if circles) as radii, depending again on your print callout. The perpendicularity checkoff is a deviation callout that tells PCDMIS if you wish to evaluate the center of your measured feature based on it's actual centerline to your leveling and datum setup vs the theorhetical centerline based your locational inputs. What it basically does is give the option of basing the location on the center right where you take your measurment in the cylindrical hole or compensating for possible taper in the centerline of the bore based on your XYZ system. Don't get blown away by this....if you're not measuring in microns and taper hasn't got tolerances in minute amounts it can be overkill. Feel free to play around with the settings and get a "comfortable zone" established on which ones you deem you really need for the task at hand. Some jobs I've done called for me to use the most technical settings the menu offers...just besure you know what your measuring is actually what you need and require.......B
        Physics dictates to man why his world acts the way it does....Chemistry tells him why it smells the way it does.

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        • #5
          FYI -

          TP has had issues since v3.207. Relative axes does not work well.

          If you have a callout to datums not in your current alignment, do a temporary alignment to those datums, then another TP. Also, if you are sending it through datapage, the secondary dimensioning has to be to a feature with a different name for both to appear. This may mean remeasuring the feature.
          http://baggy3.info/signani3.gif
          Excercise your mind,..... muscle works better than fat!!

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          • #6
            No, do not remeasure the feature. The measurements will vary slightly and if someone back calculates the TP it will not jive with your x,y values. This is how I do my TP stuff. Let's say Item10 is a TP, I first dimension the xy values calling them ITEM10_XY direct these to go only to STATS (not BOTH). Then dimension out the TP calling it ITEM10_TP (have this dimension go to BOTH). This way you have a direct correlation between you TP and xy axis'. They both are useable by DATAPAGE but the report only shows the TP for ITEM10. Make sense? I hope so. Any ?? just ask.
            Last edited by JamesMannes; 08-25-2006, 09:08 AM.
            sigpic

            James Mannes

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            • #7
              First time posting.

              I have taken the level 1 class two week ago and I am really struggling with TP. Say you have a round cap with a center hole .500" that is Datun A. The Top surface of the cap is datum B. There is 3 holes equely speced on a 2.0" bolt circle. The three holes have a .25 Dim. The FCF is TP/.010"MMC/A(MMC)/B. This FCF is located on the 3x .250" holes.

              How is the best way to go about getting the TP.

              My alignment is Level to the plane Datum B. Constructed a line from the .500" hole and one of the .250" hole. Using the line to roate arounf the Z+ Axes and using the .500" hole as the origin.

              Thanks for your help...

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              • #8
                Yourcontrol frame says -A- primary. Measure as a cylinder and level to that.

                B&S CHAMELEON/PCDMIS CAD++ V2011

                There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

                sigpic

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                • #9
                  How is the best way to go about getting the TP.
                  do you know what "TP" is? I mean what it really is ? My first suggestion would be.... thats right, you guessed it, TP training.

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                  • #10
                    Originally posted by Ironhoe View Post
                    do you know what "TP" is? I mean what it really is ? My first suggestion would be.... thats right, you guessed it, TP training.
                    TP is toilet paper?

                    B&S CHAMELEON/PCDMIS CAD++ V2011

                    There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

                    sigpic

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                    • #11
                      Originally posted by dph51 View Post
                      TP is toilet paper?
                      so with that as a reference, would TP training be about learning how to stop pooping in your jeans?

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                      • #12
                        Originally posted by Ironhoe View Post
                        so with that as a reference, would TP training be about learning how to stop pooping in your jeans?
                        That would require Potty Training then!

                        B&S CHAMELEON/PCDMIS CAD++ V2011

                        There are no bugs, only "UNDOCUMENTED ENHANCEMENTS!"

                        sigpic

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                        • #13
                          IT'S The ATACK OF THE OLD THREAD!!!!!
                          im gonna miss you bob....

                          sigpic

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                          • #14
                            WOW that was a lot of help. Thanks guys

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                            • #15
                              Originally posted by Dcoker View Post
                              WOW that was a lot of help. Thanks guys
                              Best bet is to start a different thread. Reviving one that's 5 years old is just foolish and creates confusion.

                              You took classes in PC-DMIS, but do you understand how to measure Postion on a surface plate?
                              Same principles apply.

                              As for measuring TP, I use a micrometer for thickness and roll diameter. Caliper for sheet width and length.
                              When in doubt, post code. A second set of eyes might see something you missed.
                              sigpic

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