TP question

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  • TP question

    First , My name is Mark, and i am a newbee to this forum. i would like to say i have been looking around it a bit here and you all are very helpful. Nice forum you folks have here

    I am trying to find the answer to a question i have about an inspection print-out i am gathering data from. It may be GD&T issue as well. I do understand some of it but not all.

    My question is:

    My TP has a tolerance of .004
    i understand that i have a bonus and i know how to figure this.
    my question is: On some of my data the measurement of the TP appears to go
    out of tolerance, is this normal. ? i tried to get a scan of it but my scanner is down. basically i reads

    TP....MMC....004....+.004....-.000......0047(????) OUT OF TOLERANCE 0.000

    i hope i have made this at least somewhat clear. can any give me a pointer or two?


    thanks in advance

    mark

  • #2
    Hi Mark,
    Welcome to the forum. What kind of a feature is this tp callout applied to? It must be a feature of size for there to be an MMC or LMC "bonus". The amount the feature deviates from it's Maximum Material Condition, (within size tol) can be added to the tp tol. So if you have a hole that is dia. .250 +.001/-.000 and tp.004 and it checks dia .2508 and tp. 0047 it would be in tolerance because your total tp tolerance for that hole is .0048. HTH

    p.s. try to get some GD&T training or at least a good book to help you learn the basics, they are essential to this field.
    sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

    Comment


    • #3
      Also, if you are using a version prior to 4.0 (don't use 4.0 btw) pc-dmis will not accurately report position if you try to apply a modifier (mmc, lmc) to a datum.

      Tell us more about your callout. i.e. |TP|Ø.004M|A|B|C|

      Comment


      • #4
        Thanx for responding people.
        the call out is a true position of .004 MMC to A B
        the feature is a .251 ±.0005 hole

        m concern is what is being reported on the printout and where does the number come from under the deviation column?

        in my example above the bonus is .0008.



        here is another example


        NOMINAL +TOL -TOL MEASURE DEV DEVANGLE OUTOFTOL BONUS
        MMC --- .004 --- 0 --- 0 --- .0041 --- 90. --- 0 --- .0003


        here the deviation is .0041 the thing is out of 181 reports i only have 3-5 that are reading like this..


        mark

        Comment


        • #5
          Originally posted by myouden View Post
          Thanx for responding people.
          the call out is a true position of .004 MMC to A B
          the feature is a .251 ±.0005 hole

          m concern is what is being reported on the printout and where does the number come from under the deviation column?

          in my example above the bonus is .0008.



          here is another example


          NOMINAL +TOL -TOL MEASURE DEV DEVANGLE OUTOFTOL BONUS
          MMC --- .004 --- 0 --- 0 --- .0041 --- 90. --- 0 --- .0003


          here the deviation is .0041 the thing is out of 181 reports i only have 3-5 that are reading like this..


          mark

          Under the DEV heading it reports double the actual deviation from the nominal location. Because of the bonus added through mmc, it is determined to be in tolerance and as such does not display any value for the OUTOFTOL column.

          I am guessing that you are worried about reporting .0041 as the measured and .004 as the tol. because without knowing the amount of additional bonus you can't tell if it is in tol. or out of tol.

          I get around this issue with notes. In this example I would report .0041 and make a note that says "The departure from MMC for this hole allows .000X additional bonus tolerance. The total tolerance is .004X."

          Comment


          • #6
            Originally posted by myouden View Post
            Thanx for responding people.
            the call out is a true position of .004 MMC to A B
            the feature is a .251 ±.0005 hole

            m concern is what is being reported on the printout and where does the number come from under the deviation column?

            in my example above the bonus is .0008.



            here is another example


            NOMINAL +TOL -TOL MEASURE DEV DEVANGLE OUTOFTOL BONUS
            MMC --- .004 --- 0 --- 0 --- .0041 --- 90. --- 0 --- .0003


            here the deviation is .0041 the thing is out of 181 reports i only have 3-5 that are reading like this..


            mark
            Deviation is the amount your actual measurement differs from the nominal. In the case of true position, nominal is always zero so deviation could also be read as "total true position", if this number is larger than your tolerance, there will be a value in the "out of tolerance" column showing the amount deviation exceeds tolerance. HTH
            sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

            Comment


            • #7
              Originally posted by Wes Cisco View Post
              Deviation is the amount your actual measurement differs from the nominal. In the case of true position, nominal is always zero so deviation could also be read as "total true position", if this number is larger than your tolerance plus any bonus, there will be a value in the "out of tolerance" column showing the amount deviation exceeds tolerance. HTH
              You forgot about bonus there Wes.

              Oh boy, I've never really thought about it but... Lets say you have two that are called out |TP|Ø.004M|A|B|C| and one measures .0042 and the other .0047. Now, with the first lets say you get .0001 bonus. It will show OOT .0001. Now, the second lets say you get .0006 bonus. It too will read as only .0001 OOT

              Comment


              • #8
                ok but then,but in the both the examples i have posted there is nothing on the OOT column. in other word the reported deviation reads zero for my examples.

                also is HTH an acronym or is that your signature?

                Comment


                • #9
                  HTH hope this helps
                  sigpic
                  if you had soap on a rope it would be tied to yer ankle

                  Comment


                  • #10
                    Originally posted by Goodluck View Post
                    You forgot about bonus there Wes.

                    Oh boy, I've never really thought about it but... Lets say you have two that are called out |TP|Ø.004M|A|B|C| and one measures .0042 and the other .0047. Now, with the first lets say you get .0001 bonus. It will show OOT .0001. Now, the second lets say you get .0006 bonus. It too will read as only .0001 OOT
                    Nope, I did not forget about the "bonus", but I had already explained how deviation in size added to tp tolerance in a previous post and did not see the need to repeat myself here. (apparently I was mistooken.) I have seen exactly what you list as an example many times.

                    If there is nothing but goose eggs in your "out of tolerance" column, then the software thinks you have enough tolerance to cover the amount over .004 based on the size of the feature. If your hole is .251+/-.0005 and it checks .2513 then you add .0008 to your tolerance of .004.

                    HTH = Hope This Helps
                    sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

                    Comment


                    • #11
                      Got it...thanx to all who took a couple of minutes to help out.


                      mark

                      Comment


                      • #12
                        Originally posted by Wes Cisco View Post
                        Nope, I did not forget about the "bonus", but I had already explained how deviation in size added to tp tolerance in a previous post and did not see the need to repeat myself here. (apparently I was mistooken.)
                        C'mon Wes, you know I'm a bit dense when it comes to certain things - cough scroll lock cough.

                        I did not mean to offend but thought it important to note that as I thought the confusion was in the fact that his measured value was greater than the tolerance and the OOT column was showing zero.

                        Comment


                        • #13
                          Originally posted by Goodluck View Post
                          C'mon Wes, you know I'm a bit dense when it comes to certain things - cough scroll lock cough.

                          I did not mean to offend but thought it important to note that as I thought the confusion was in the fact that his measured value was greater than the tolerance and the OOT column was showing zero.
                          No offense taken. You are correct, that appears to have been the source of his confusion. As I said earlier, you really need to master at least the basics of GD&T for this line of work.
                          sigpic"Hated by Many, Loved by Few" _ A.B. - Stone brewery

                          Comment


                          • #14
                            Sorry to bother you folks with such elementary questions and i certainly hope that you fellas go out and have a beer together after a long day.
                            I do understand that you get to add the bonus tolerance to the positional tolerance. MY question was more in what the software was doing with the numbers. You fellas have helped my understand that

                            Like i said
                            Thanx for Helping me out

                            mark

                            Comment


                            • #15
                              Originally posted by myouden View Post
                              Sorry to bother you folks with such elementary questions and i certainly hope that you fellas go out and have a beer together after a long day.
                              I do understand that you get to add the bonus tolerance to the positional tolerance. MY question was more in what the software was doing with the numbers. You fellas have helped my understand that

                              Like i said
                              Thanx for Helping me out

                              mark
                              You are welcome. I'd go for a beer but Wes likes whiskey. How about you?

                              Comment

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