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tangential plane - ISO and ASME

aversario_aaaversario_aa Member Posts: 3
edited June 3 in Drawings
Hi,

I'm working with ISO. Why wouldn't let me choose tangential modifier on a plane for true position?


edit: changed thread title to include ASME too. But be sure to read through comments.

Best Answer

  • PeteYodisPeteYodis Posts: 360
    edited June 3 Accepted Answer
    @aversario_aa I have created a ticket and tied you to a bug I filed for us to make this correct for the newer ISO standard needs.  Thanks for pointing this out.  We'll get it supported.  

    ASME Y14.5 at least as of 2009 did have support for the tangential plane modifier, but there seems to be some uncertainty about what it can apply to.  I have quite an extensive reference that mentions it is appropriate for parallelism, perpendicularity, and angularity.  In general we try not to block users from doing something that is not clearly wrong.  Sometimes we do block annotations that would be clearly wrong.  Some areas get to be a bit gray and we try to accommodate as best as possible without creating additional un-desired complexity if we can avoid it.  

Answers

  • PeteYodisPeteYodis Moderator, Onshape Employees Posts: 360
    edited June 3
    @aversario_aa I'm not sure that tangential plane is a correct modifier on true position tolerances, or at least not explicitly stated in reference materials I have been using.  If it is a correct use of that modifier in this case then we can certainly adjust the GDT tool to suit. 

    I suspect in this case you are really wanting a parallelism tolerance control with a tangential plane modifier.  We support tangential plane modifiers on parallelism, perpendicularity, and angularity.  If you decide parallelism is correct, then the 30 dimension will not be basic but indeed need a defined tolerance on it.  It's certainly possible the dimensional tolerance along with the parallelism control will give you what you need.  

    Let me know your thoughts.  
  • aversario_aaaversario_aa Member Posts: 3
    Hi Pete,

    thank you for you attention on this one.
    The latest for now is ISO 1101:2017 which will describe the use case of such modifiers. It is in paragraph 8.2.2.2.2. and is applicable to true position also.
    Thank you for suggesting the way with parallelism, it sure can be done in combination with some other characteristic, but I can't see why I wouldn't use TP (at least in this case), if it's clearly allowed in ISO.
    I don't have access to ASME, but I don't think that ASME even allows to put a TP on a plane if it's parallel to the datum plane. Someone please confirm.
  • PeteYodisPeteYodis Moderator, Onshape Employees Posts: 360
    edited June 3 Accepted Answer
    @aversario_aa I have created a ticket and tied you to a bug I filed for us to make this correct for the newer ISO standard needs.  Thanks for pointing this out.  We'll get it supported.  

    ASME Y14.5 at least as of 2009 did have support for the tangential plane modifier, but there seems to be some uncertainty about what it can apply to.  I have quite an extensive reference that mentions it is appropriate for parallelism, perpendicularity, and angularity.  In general we try not to block users from doing something that is not clearly wrong.  Sometimes we do block annotations that would be clearly wrong.  Some areas get to be a bit gray and we try to accommodate as best as possible without creating additional un-desired complexity if we can avoid it.  
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