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Can a Datum feature reference itself in Y14.5M (GD&T)?

Can a Datum feature reference itself in Y14.5M (GD&T)?

Can a Datum feature reference itself in Y14.5M (GD&T)?

(OP)
If I have a part with two datums, datum B - a hole and datum C - the width of a slot and I want to tolerance the length of the slot can I use a positional tolerance that references A|B|C or can I only use A|B because the slot is C?

Thanks,

RE: Can a Datum feature reference itself in Y14.5M (GD&T)?

Some misinformation provided.  You state there are only 2 datum features, B and C.  Later you mention A.  Whis is true?

You could make use of the width C in positioning the length feature.  

RE: Can a Datum feature reference itself in Y14.5M (GD&T)?

(OP)
Sorry,  datum a is the surface that datum B & C are passing through.

RE: Can a Datum feature reference itself in Y14.5M (GD&T)?

I agree with ringman.  Datum C is the width of the slot, not the slot itself, so you could reference the length of the slot to A, B and C.  

RE: Can a Datum feature reference itself in Y14.5M (GD&T)?

(OP)
Physically, what would that mean?  How could the length of the slot vary, positionally, with respect to the width of the  slot?

RE: Can a Datum feature reference itself in Y14.5M (GD&T)?

Physically it does seem meaningless.  It would appear to control the perpendicularity of the length of the slot relative to the width of the slot.

RE: Can a Datum feature reference itself in Y14.5M (GD&T)?

  ASME now controls the standard, not ANSI.  Try asking this question in the Drafting Standards & GD&T forum, and you may get a better answer.  

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