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ASME - Datum Translation


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Interesting. What is the allowable movement for the gauge pin? Is it the Position tolerance of C to A B?

Marc, I've read that. What I got out of it is that they are trying to assure that the tertiary is only controlling the degree of freedom that it is allowed to. In this case it would be the rotation about the Z. The standard is saying though that without this modifier on the datum you aren't truly gauging the part correctly. Calypso is already taking care of this for you because it follows the Can/May/Must rule.

I just thought that this was an interesting one.
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I have never seen this on a print for an actual part. I admit that my understanding of the translation modifier is lacking, but I don't see it being better than the true position and an MMB modifier.
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That is the Datum Translation symbol. Back during the Y14.5-1994 days there was a debate about how to interpret a datum reference frame where the secondary and tertiary datum features are Cylinders. Technically, the datum simulators would be fixed at their basic location from one another, then expanding (or contracting or external features) until they make contact with surfaces of the datum features. This often led to some undesired effects with how the tertiary datum constrains the final rotational degree of freedom because the datum simulator when it expands doesn't make full contact on the surfaces. The datum translation modifier unlocks the datum simulator from the basic location of its preceding datum and allows it to slide back and fourth to allow maximum contact of the datum simulator on the surfaces. This better aligns with the functional design of certain assemblies, most notably when you have a configuration of dowel pins that fasten into a hole-slot configuration.

This is sort of hard to explain in text. So If that doesn't make sense, check out this video from Tec-Ease.
https://youtu.be/fYbu-lPSTlk
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Lol.

In all seriousness, I see how the gauge is supposed to work in principle.

Question though, how would this look where the tertiary datum is is not on the same axis line? In all of the cases that I've seen it, the tertiary datum is either parallel to the x or y axis. How would this work if it is canted at say 45°? The example drawing that I supplied is defined this way.

Maybe I'm over thinking this whole situation.
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All new stuff to me, so forgive the dumb question. Would the sliding datum -E-
simulator be restricted from moving less than 65.95 and no more than 70.05?
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