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how do I align this to match GD&T so it can be correctly dimensioned?

I've inserted a snippet of a part I'm currently working with its not the entire print. can someone explain in the simplest of terms how I need to align this part so when I measure my dimensions it does so correctly? also can someone explain why you chose the methods that you used to align the part. I'm very new to this world I've got some experience but mostly self taught I'm familiar with the software. but very unfamiliar with the terminology and when and where to use the best practices. for instance when is a best fit better then a iterate alignment. or when to construct a feature in order to measure/align vs a measured feature or a constructed point vs a vector point? please help me I need a mentor here and unfortunately I'm the only cmm operator at my facility. 

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  • Datums A & B are using datum target areas so the easiest way to do it would be to measure auto planes for A1, A2, B1 & B2.  You can set the XYZ centre co-ordinates, switch the hit pattern to radial instead of square, and then use the spacer to define the Ø10 area (spacer = 5).  Once you've measured them all, you need to construct BFRE planes using the hits, datum A plane from the hits of A1 & A2 and datum B plane from the hits of B1 & B2.  You can then open the datum definition dialog (insert>dimension>datum definition), pick the constructed datum A plane for datum A, the constructed datum B plane for datum B and then click the "common datum" checkbox and pick A & B to define common datum A-B.  For datum C, you would need to measure the 3xØ6.6 holes (ideally as cylinders rather than circles).  and In the datum definition dialog, you would pick all 3 holes when defining datum C.  The same approach would be required for the 3xØ4.79 datum D holes.  You can then measure the rest of the part and add geometric tolerance commands for the various callouts.

    If you wanted to create alignments that replicated the datum reference frames it would be a little harder.  For example, to do you would need to construct another BFRE plane for datum A-B from all of the hits of A1, A2, B1 & B2 - assuming they are all at the same height - this would be your LEVEL.  You would then need to add a 2D rotate & translate best-fit of the 3x datum D holes.

  • if I were to try to align but A and B are NOT on the same work plane, would you use a midplane for the level of the alignment?

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