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Hello Guys
here is one question haunting in my head for months. please help see the attached image: [IMG]http://www.engineersedge.com/engineering-forum/attachment.php?attachmentid=1259&stc=1[/IMG]
so can I remove the MMC modifier in the feature control frame.how can I imagine two holes's simulator (if I remove the MMC modifier) adjusting in the same time or not?
Without the modifier specified for Datum B the Datum is established at RFS.. With a CMM, one would establish several circle starting at the top of the as-built hole features as well as several locations spaced along the length of each Datum B hole feature. From these circle measurements the CMM would establish a Datum axis.
To establish Datum B at RFS in a fixture -- one would design the fixture with two expanding precision dowel pins or similar feature located at the basic dimension location and/or orientation. The as-built part is placed in the fixture with the expanding dowel pins collapsed and then the Datums are established and maintained in the order of precedence specified.
[IMG]http://www.engineersedge.com/engineering-forum/attachment.php?attachmentid=1260&stc=1[/IMG]
Expanding Pin Example
[B]"[COLOR=#333333] the Datums are established and maintained in the order of precedence specified." [/COLOR][/B][COLOR=#333333]but for hole Dia17.2, two holes of B are its reference, which one will be the primary one , which one will be the secondary one, OR is it possible to change diameters for two references simultaneously?[/COLOR]
[QUOTE=lucien tian;10220][B]"[COLOR=#333333] the Datums are established and maintained in the order of precedence specified." [/COLOR][/B][COLOR=#333333]but for hole Dia17.2, two holes of B are its reference, which one will be the primary one , which one will be the secondary one, OR is it possible to change diameters for two references simultaneously?[/COLOR][/QUOTE]
The primary datum is "A", which is established and maintained while establishing Datum "B". The Datum B holes features are established simultaneously.