"TRUE" Meaning
"TRUE" Meaning
(OP)
I've just had a customer ask about the use of "TRUE" with a hole callout. Per ASME Y14.5-1994, it is used when dimensioning a radius in a view which does not show the radius' true shape (para 1.8.2.3). For years, I've also used it for hole callouts, because holes are so closely related to radii. Am I wrong to use it in this way?
Believe it if you need it or leave it if you dare. - Robert Hunter





RE: "TRUE" Meaning
Generally, "true" means theoretical such as true position is the theoretical centres while true profile is the theoretical profile. In both cases, they are usually shown with basic dimensions.
A lot of people use true position when they should be talking about the positional tolerances of holes or pins.
Dave D.
www.qmsi.ca
RE: "TRUE" Meaning
Believe it if you need it or leave it if you dare. - Robert Hunter
RE: "TRUE" Meaning
I see no issues with using it on a hole.
Chris
SolidWorks/PDMWorks 08 2.0
AutoCAD 06
ctopher's home (updated 10-07-07)
ctopher's blog
RE: "TRUE" Meaning
"Art without engineering is dreaming; Engineering without art is calculating."
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RE: "TRUE" Meaning
I feel pretty comfortable about leaving things as they are with regards to "true" holes. It is not a great leap of logic to see how it can apply. What does bother me though, is that the customer actually had engineers asking the meaning. But, then again, seeing how they use GD&T, it isn't all that suprising after all
Believe it if you need it or leave it if you dare. - Robert Hunter
RE: "TRUE" Meaning
Isn't a hole just a continuous rad anyway so I don't see why you couldn't use it.
KENAT, probably the least qualified checker you'll ever meet...
RE: "TRUE" Meaning
Believe it if you need it or leave it if you dare. - Robert Hunter