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Carey Ryerson · Guest

This isn't related to Pro/E as much as it is to general drafting, but what
the hey...
1. In my copy of ASME Y14.5M-1994 Standards (reaffirmed 1999), I do not see
any references made to "ordinate dimensions". Does anyone know if these are
covered in any update or where I might find some best practice information?
2. I have seen it done, but I don't know if it is a best practice to have
ordinate and linear dimensions on the same view. Any thoughts?

Thanks,
Carey

NOTE: when replying, remove "DELETE" from email address

Jeff Howard · Guest

David Janes · Guest

: "Carey Ryerson" <careyrDELETE@coloradotime.com> wrote
: This isn't related to Pro/E as much as it is to general drafting, but what
: the hey...
: 1. In my copy of ASME Y14.5M-1994 Standards (reaffirmed 1999), I do not see
: any references made to "ordinate dimensions". Does anyone know if these are
: covered in any update or where I might find some best practice information?

Ordinate dimensioning is just a variety of coordinate dimensioning. Whatever Y14.5
says about this method of dimensioning applies to ordinate. It would not be
covered under best practices of any kind the only 'best practice' system involves
the use of geometric dimensioning and tolerancing, Six Sigma and other 'variation
management' techniques.

: 2. I have seen it done, but I don't know if it is a best practice to have
: ordinate and linear dimensions on the same view. Any thoughts?

The use of a linear dimension, with the rest in ordinate, is simply a way of
'chaining' dimensions to allow the dimensional relation between two feartures to
be specified with greater precision and more tightly toleranced than the default
tolerance would if the second feature were ordinate dimensioned with the rest.
Take a series of holes pattened an inch apart and default toleranced to
±.005. This would allow a maximum variation of .020 between the closest and
furthest spacing between any two holes. Let's say you wanted holes 3 and 5 to vary
no more than .002 between each other. How would you accomplish this with ordinated
dimensions. Well, you'd have to change the tolerance on each hole's location to
±.0005 or ten times the precision of the default. Another way is to chain the two,
letting the first vary by the default and giving a linear dimension to hole number
5 of ±.001 or merely five times the precision on only one of the holes.

David Janes

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