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PC-DMIS 2020R2 – Profile ISO 1101

Aaron Baldauf
Hi & neil.challinor

I would like to ask you about your opinion about this issue.

We often have profile callouts similar to this |ꓵ|0.1 UZ -0.1| on our customer drawings,
where both tolerance “borders” are on one side of the nominal geometry.
I have seen these callouts since a few years from customers in the automotive industry as well as other industries.
I was looking forward to the new GeometricTolerance command to finally measure these callouts.


​​
Now it looks like the new command doesn’t support this kind of evaluation (at least I can’t get it to work).
PC-DMIS only allows me to put a value of maximum half the tolerance after the UZ modifier.
So I can’t have both “borders” on one side of the nominal geometry.

​

In my opinion these callouts are valid according to ISO 1101 as the standard doesn’t prohibit,
that both tolerance “borders” are on the same side of the nominal.
For me they would serve the same purpose as ISO Code fittings (egg. g6).

Furthermore as you also support the OZ modifier the calculation should already be supported by PC-DMIS.

What is your opinion on this?
Is this a valid callout but is not supported by PC-DMIS?
Do I understand the standard wrong?

Has anybody else these kind of callouts? What is your opinion about this?

Thank you for the answer.
  • Hi Aaron,

    I agree with your comment and currently PC-DMIS is too restrictive for the offset tolerance value (currently 1/2 the total tolerance). ISO and ASME are not clear regarding a maximum value as you have indicated. We plan to change the rule for the max offset value to be equal to or larger than the total tolerance value for ASME and ISO in a 2020 R2 SP. I would like your feedback on this (ISO perspective), please e-mail me if you would like to discuss this further and can share some example callouts we need to support.

    Thanks,

    Rob
  • This has been an issue for many people for a long time. I don't use 'profile', I dimension individual points, and you can do this using the "T" axis. Been some lively conversations about this 'elsewhere', but there is nothing in either standard forbidding having both limits on one side of nominal. I've been dealing with that for years.
  • T value splitting the profile tolerance, never go wrong!

    In your case, you tol only goes one way but you already know that


  • Thank you for the answer.

    At the moment I have a part that calls for |ꓵ|0.0095 UZ -0.00975|. So greater than one time the total tolerance value.
    Unfortunately, I don’t have access to the old drawings as I changed the company recently.

    I personally would prefer to have no max. offset rule at all but maybe a warning when the offset is greater than two times the total tolerance value,
    which the user would have to accept? I think with a hard cap the same problem can occur again in the future. As you said the standard doesn't rule out big offsets. One time the total tolerance value it definitely too small, as I have seen bigger offset values before.

    What about the OZ modifier in PC-DMIS? Is there a max. offset value in the calculation behind the scene?

    If I will find any more drawings I will send you an email, could you send me the address in a PM?
  • in reply to Aaron Baldauf
     , you already have my email so you can send them to me if you like - I can forward things to Rob if necessary.
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