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eServ

New member
Anyone know how to create a composite tolerance (in 2001), so that when you select the datum reference Secondary, they Primary datum reference does not show in the tolerance as well?
 

eServ

New member
It's been a while, but I think when I asked the question I was referring to True Position. I wanted to put a Secondary Datum reference ONLY, and when you select Secondary, Pro/E puts the Primary and the Secondary. I was converting a drawing to Pro and that is what the drawing specified.
 

Tunalover

New member
The drawing is not specifying a composite positional tolerance correctly. A primary datum must be specified as a mininum in the bottom entry (in-pattern tolerance).



As composite pt feature control frames go, the top entry is pattern-locating and should specify enough datum references to prevent the part from translation (e.g. states a specific way the part must be held for the tolerances, pattern-locating and in-pattern, to apply). In the pattern-locating segment, the first datum reference appearing from left to right is the primary. The second is the secondary. The third is the tertiary. (If a datum reference is a hole, then that datum reference will provide two datums thus constraining translation in two directions at once. In that event, only two datum references are required.)



The bottom segment is the in-pattern tolerance, sometimes called the feature-relating tolerance. Its tolerance value MUST be less than the pattern-locating tolerance. That tolerance is usually presented with only one datum reference, typically the same datum reference as used as the primary in the top segment.



Knowing nothing about the design, we can't determine if the drawing is calling out the right hole size, datum references, and positional tolerances to insure fit, however. If you can fully define what the part(s) is(are) that fit with the feature pattern then we could fix the dimensioning and tolerancing. I would help with that at no charge.



Tunalover
 

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