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Noob to gd&t needing guidance
First off i would like to say hello to everyone..So hi :o
I'm new to gd&t as a inspector and have done some basic jobs which call for gd&t but some things have been holding me up in my progression. Iam based in the uk and work to iso9001 standards and wondered if someone could help me out with the drawing attached?
As i understand hole position tolerance is measured from the datums stated in the feature control frame. The drawing i have attached is from a customer who use's there own datum reference frame to take measurments from and restrict 12 degrees of freedom,Which i understand.
The part i'm confused about in the upper drawing arrowed is the positional tolerance that use's hole(Datum) "c" as the tertiary. Do use hole(Datum) B for dimensions left to right of itself and then C for dimensions above and below? So basically if i ran a line through B and a line through C (perp to each other)the point at which the two meet would be my coordinate system?
Also the same applys to the drawing below it where profile tolerance which calls up datums ABC. Where would my measurments come from? I have measured from the red line highlighted as it is parallel but is this correct?
Any feedback is greatly appreciated
Nick