[To...] Posted September 19, 2019 Share Posted September 19, 2019 Does anyone have an issue with this position call-out? In particular, the basic dimension location from a feature that is not a datum feature. Do you disregard the basic dimension and calculate the nominal position from Datum A? . . Link to comment Share on other sites More sharing options...
[Za...] Posted September 19, 2019 Share Posted September 19, 2019 I always argue the DRF supersedes any contradictory basics. Even if it doesn't quite make sense. But in the real world it depends on what the customer wants, they are the ones paying for the inspection. Link to comment Share on other sites More sharing options...
[Aa...] Posted September 19, 2019 Share Posted September 19, 2019 If the basic dimensions are intended to be queried from the CAD model, then where they put the basic dimensions on the print doesn't really matter. Otherwise, they should at least include enough basic dimensions on the print for you to do the math to determine the distance between the controlled feature and the datum. There's no requirement in the ASME standard that the basic dimensions go directly from the datum to the controlled feature without passing "Go" or collecting $200. Link to comment Share on other sites More sharing options...
[Aa...] Posted September 19, 2019 Share Posted September 19, 2019 I agree with Zach. The position is controlled in relation to the DRF. Link to comment Share on other sites More sharing options...
[An...] Posted September 19, 2019 Share Posted September 19, 2019 Please sign in to view this quote. Link to comment Share on other sites More sharing options...
[Br...] Posted September 19, 2019 Share Posted September 19, 2019 It is possible to chain the basic dimensions through multiple features as long as they end up at the Datum features referenced. Although that probably doesn't make sense in this case. Say that plane had a profile tolerance applied to it, and it had a basic back to -A-, that would effectively get your diameters with the position tolerance basically located to the DRF as well. ASME Y14.5-2009 para 7.2 states: Please sign in to view this quote. In other words, they have to come from the Datums. This makes sense becouse its the Datums that are controlling the location. Link to comment Share on other sites More sharing options...
[An...] Posted September 19, 2019 Share Posted September 19, 2019 Is this a legal callout? Is this a callout that gives the operator the chance to add three valus? Or is this something that no one understands? See attached.Contribution_19_09_2019.pdf Link to comment Share on other sites More sharing options...
[Aa...] Posted September 19, 2019 Share Posted September 19, 2019 Please sign in to view this quote. Interesting question. This might not be the line of thinking you were looking for, but no, that doesn't jibe with Y14.5. For one thing, a directly toleranced quantity can't be substituted for a basic dimension. For another, position tolerances can only be applied to features of size. For planes, profile needs to be used. Link to comment Share on other sites More sharing options...
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