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Can I establish a compound datum?

Question asked by Kevin Hawkinson on Nov 18, 2009
Latest reply on Apr 22, 2010 by Kevin Hawkinson

In one of one of my GD&T books, they mention "Compound (multiple) datums" i.e. a part mounted between centers, which is the way my part will be made.

They show datum A and B being the center drill spot on each end of a shaft, with runout callouts referencing datum A-B.

I have not been able to reproduce this in SW for several reasons.

 

When I am selecting datums for the Auto Dimension Scheme:

1- SW is not accepting a conical surface (i.e. a center drill spot) for a datum.

2- I can't create a compound hole (or I can't get SW to recognize a compound hole).

 

It seems backwards to turn a part between centers, with a cylindrical boss as datum, and then specify runout on the center drills.

 

Any ideas, or is it  just a case of "you can't get there from here"?

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