【转帖】asme y14.5m-920080

yang686526

asme y14.5m-(2008)?
has anyone had the opportunity to look over the new draft for asme y14.5m?  any comments on it?  anyone else have any comments about 1994 that they would like to see changed or added?
matt lorono
cad engineer/ecn analyst
silicon valley, ca
there are some comments here ->
  i know about that thread.  i posted it in myself.  there's not really any content in it.  i figured i'd asked directly about it, now that the draft has been out a while; and also to see if anyone else had comments about 1994 that they hope is changed.
matt lorono
cad engineer/ecn analyst
silicon valley, ca
my understanding is that they've been fighting the sf battle a long time.  looks like the spotfacers won this round.
i did hear that many of the tough decisions where put off until next time, so this update may not be all the much different.  i haven't see it though.
  
matt lorono
cad engineer/ecn analyst
silicon valley, ca
the definition for profile is consistent with 14.41-2003 in that it uses the u modifier instead of phantom lines to define unequal bi-lateral tolerance zones. that a welcome change imho.
powerhound, gdtp t-0419
production supervisor
inventor 2008
mastercam x2
smartcam 11.1
ssg, u.s. army
taji, iraq oif ii
great!  i was hoping that they wouldn't overlook that.
believe it if you need it or leave it if you dare.fff"> - robert hunter

powerhound,
curious, what's the difference between spotface and counterbore according to the proposal?
matt lorono
cad engineer/ecn analyst
silicon valley, ca
cbore has a depth noted, sf is minimum depth to achieve flat surface of noted diameter.
believe it if you need it or leave it if you dare.fff"> - robert hunter

fcsuper,
2008 proposed gd&t tips
summary of changes
by gary whitmire
a proposed new y14.5 geometric dimensioning and tolerancing standard has just been officially released for comments. if past practice is any guide, this draft will become the new standard in a few months. this standard will replace the 1994 gd&t standard. it is expected that all organizations which now use the 1994 standard will eventually switch to this 2008 gd&t standard. the proposed standard itself is 264 pages long, so following is a summary of a few of the changes from the 1994 standard:
a.    there are new symbols and dimensioning conventions for:
?    all over as used in profile control
?    continuous features
?    independency
?    unequally-disposed tolerance zone
?    moveable datum target
?    datum translation
b.    there is a guide to the six degrees of freedom for datums
c.    non-perpendicularity of intersecting surfaces is addressed
d.    there is a change under spotface
e.    basic dimensions are clarified
f.    there is a clarification on limit of size
g.    there is a change to rule 1
h.    tolerance of position has been reformatted
i.    dimensions defined by cad data have been addressed
j.    the effect of datum references in positional tolerances is explained in degrees of freedom
k.    control of coaxial features is addressed
l.    there are new boundary methods
m.    there are a number of new terms, including:
?    maximum material boundary (mmb)
?    least material boundary (lmb)
?    true geometric counterpart (tgc)
?    regardless of feature boundary (rmb)
?    degrees of freedom (dof)
n.    there are twenty (20) new definitions
o.    a contoured surface can be a datum
p.    there is a new datum symbol placement requirement
q.    there is a new leader line symbol

ok, now i'm confused.  i thought a contoured surface could already be used as a datum, as long as it was tied down to the three primary datums (para 4.5.10.1).  is it now going to be allowed as a primary datum?
i am eager to look the new standard over, though i'm not so sure how eager i am in implementing it.
believe it if you need it or leave it if you dare.fff"> - robert hunter