[SH...] Posted July 26, 2020 Share Posted July 26, 2020 I just go through the ASME Y14.5 2018 standard instead of tolerance of location used in 2009 standard, it talking about tolerance of position and also it does not discuss about concentricity and symmetry tolerance. Is it true that 2018 governing committee terminated concentricity and symmetry?? Link to comment Share on other sites More sharing options...
[He...] Posted July 26, 2020 Share Posted July 26, 2020 Yes, it's gone! Good riddance. Hope it never comes back. Link to comment Share on other sites More sharing options...
[SH...] Posted July 27, 2020 Author Share Posted July 27, 2020 So, true position will fire in all cylinders!!! Link to comment Share on other sites More sharing options...
[Da...] Posted July 27, 2020 Share Posted July 27, 2020 Does that mean that 2018 also wouldn't allow to form "symmetry plane" datums? Link to comment Share on other sites More sharing options...
[SH...] Posted July 27, 2020 Author Share Posted July 27, 2020 Please sign in to view this quote. Definitely not.I think instead of symmetry we have used midplane for true position.but I can understand why concentricity is not using. Using true position for circle the circle is better than Concentricity?? Link to comment Share on other sites More sharing options...
[Cl...] Posted July 27, 2020 Share Posted July 27, 2020 Correct me if I'm wrong, but isn't the formula for calculating concentricity and diametric true position the same? If that's the case, why have both in the first place? Link to comment Share on other sites More sharing options...
[De...] Posted July 27, 2020 Share Posted July 27, 2020 Clarke, true position and concentricity are (were) different. True position is the boundary wall of a feature. Concentricity was calculated by generating the mid point of symmetrically opposed points, and validating this point fell within a cylindrical tolerance band. My favorite question for engineers/designers who wanted to use concentricity was, can you check the concentricity of a 6 pointed bolt head to the thread centerline? By definition, you can, but most thought it was not possible. Link to comment Share on other sites More sharing options...
[Ch...] Posted July 27, 2020 Share Posted July 27, 2020 ISO concentricity is same as position. This is how calypso calculates concentricity. In ISO, concentricity is basically a special case of position where both features have the same axis. ASME concentricity is/was totally different. The only way to get Calypso to report ASME concentricity is to make your own strategy or used that cool macro from Ryan Stauffer. All that being said. I'm glad the powers that be killed ASME concentricity. Link to comment Share on other sites More sharing options...
[Cl...] Posted July 27, 2020 Share Posted July 27, 2020 We make a part for brain surgery. It is a step cylinder about 6" long. One OD is .309 for about 3.5". Tthe smaller diameter is .158 for the remaining length. It has a sharp point on the .158 dia end. This part is robotically guided into the scull. There is a true position callout for the sharp .158 tip back to the large OD. With that in mind, is the true position callout correct, or should it be concentricity, or even runout? Link to comment Share on other sites More sharing options...
[Ch...] Posted July 27, 2020 Share Posted July 27, 2020 From my limited GD&T understanding. I think position is a legit callout. Position to one datum can control location(ISO concentricity in this case) as well as angularity. I tend to like that more designers are using position to control more that just location. For example, position and angularity. Link to comment Share on other sites More sharing options...
[Ky...] Posted July 28, 2020 Share Posted July 28, 2020 What is really bad is the customer can call out to an older ASME Y14.5 spec and you have to hold it to that spec. We have a part that has been built since 2011 and just had the Rev rolled. The customer still calls for ASME Y14.5M-1994. So it's great that the spec was changed but legacy parts won't change standards from what I was told. Because that is what the machines were certified with. Link to comment Share on other sites More sharing options...
[Ke...] Posted July 28, 2020 Share Posted July 28, 2020 Please sign in to view this quote. No, what's *really* bad is when you see the statement on a print that says "...to the latest version of Y14.5", which means that whenever the standard changes, then you have to figure out which parts/programs need to be revised. Can someone clarify if this type of a statement s even "legal"?? Link to comment Share on other sites More sharing options...
[Ky...] Posted July 28, 2020 Share Posted July 28, 2020 Man that is worse then mine. Mine don't change. I would hate to have to go thru and figure out which programs I have to change because of that statement!!! Link to comment Share on other sites More sharing options...
[Ke...] Posted August 18, 2020 Share Posted August 18, 2020 Please sign in to view this quote. Any chance you have that macro handy? Link to comment Share on other sites More sharing options...
[Ri...] Posted August 18, 2020 Share Posted August 18, 2020 Please sign in to view this quote. viewtopic.php?f=13&t=575&start=10 Link to comment Share on other sites More sharing options...
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