Drawing from late 80's confusion relating to Concentricity Call-out
Drawing from late 80's confusion relating to Concentricity Call-out
(OP)
Hi All,
Question relating to the concentricity call-out between the .3750 & .250 diameters. .3750 diameter called to be concentric to Datum D but when looking at the Datum D the datum is comprised of both diameters (.250/.3750?).
So i'm confused as to what .3750 needs to be concentric to given this call-out. Is this more of a call-out in reference to the .750 distance where Datum D comes off of and somehow .3750 needs to be concentric to this distance?
Can anyone shed some light as to what exactly is this callout for?
thank you
Question relating to the concentricity call-out between the .3750 & .250 diameters. .3750 diameter called to be concentric to Datum D but when looking at the Datum D the datum is comprised of both diameters (.250/.3750?).
So i'm confused as to what .3750 needs to be concentric to given this call-out. Is this more of a call-out in reference to the .750 distance where Datum D comes off of and somehow .3750 needs to be concentric to this distance?
Can anyone shed some light as to what exactly is this callout for?
thank you





RE: Drawing from late 80's confusion relating to Concentricity Call-out
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drawing from late 80's confusion relating to Concentricity Call-out
thanks
RE: Drawing from late 80's confusion relating to Concentricity Call-out
If the drawing was done in 1989 the standard might be ANSI Y14.5M 1982.... I think. Regardless the datum's are not called out correctly but it is extremely common to see them attached to a center-line. And such is the confusion as to which diameter that center-line belongs to...
lightweight, cheap, strong... pick 2
RE: Drawing from late 80's confusion relating to Concentricity Call-out
What is Engineering anyway: FAQ1088-1484: In layman terms, what is "engineering"?
RE: Drawing from late 80's confusion relating to Concentricity Call-out
So what's wrong?
Of the four datum callouts, only [-C-] is apparently correct.
None of the others is unambiguous. Centerlines are not available for attaching datum feature symbols, for just this reason. I've just looked at a pre-1965 explanation by Lowell Foster and it clearly shows that either the datum callout is applied to the dimension, or to a specific surface; not to centerlines, so it's not as if it was OK in 1965. I don't have a copy of the 1966 version of Y14.5.
The book treats concentricity almost the same as position. While not a copy of the standard, it was a company reference for Honeywell.
Without the tolerance analysis to tell what was supposed to by controlled, this drawing is a lost cause.
**Ignorance in 1965 is hardly unexpected given the likely lack of decent explanation and examples. 40-50 years should have improved things.
Just a weak nit to pick, "comprise" is a synonym for "composed of" so "comprised of" is the same as "composed of of." In particular the past tense "comprised" is a synonym for "used to be composed of" as in "The Soviet Union comprised several republics." from http://www.thefreedictionary.com/comprised. I only know this from resolving the ambiguity in many sentences.
RE: Drawing from late 80's confusion relating to Concentricity Call-out
lightweight, cheap, strong... pick 2
RE: Drawing from late 80's confusion relating to Concentricity Call-out
RE: Drawing from late 80's confusion relating to Concentricity Call-out
thank you everyone else for the input =)
RE: Drawing from late 80's confusion relating to Concentricity Call-out