2 Datum Alignment

Can someone please help me figure out the best way to set up an alignment with only 2 datums? The print I am working off only has a datum A plane and a datum b diameter and is wanting some gd&t position information just using A & B instead of the A, B and C that I am used to.

Thanks

KIRBSTER269 over 7 years ago

First of all the diameter is it parallel or perpendicular to plane? If diameter is perpendicular to the plane, It's quite simple. Datum A, lets say is Z and Diameter would be X and Y, you would have to try to find a straight edge on the part to clock it to. That way it locks the part down, just make sure it is a good edge. If its Parallel to Plane, that will be a problem then you only account for 2 axis.
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bfire85 over 7 years ago

I agree with Kirby above. Find a straight edge to clock the rotation to. If it's a round part, sometimes I will use something on the fixturing to clock to, just to get all 6 DOF locked down.
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JEFMAN over 7 years ago

I would say : construct your alignment as you want (with 6 DOF !), then use FCF with 2 datums, and it should work...
(I'm not at the cmm to check it...)
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bigtallanddopey over 7 years ago

I would say : construct your alignment as you want (with 6 DOF !), then use FCF with 2 datums, and it should work...
(I'm not at the cmm to check it...)

I would do this also, creating the FCF in exactmeasure is the only way to achieve this as it is written on the print.
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