【转帖】revision

yang686526

revision
question in regards to revisions of drawings. i won't get into the details concerning why these are issues. i can't find anything in asme y14.35 or y14.100 that covers these situations.
issue 1:
sometimes we have drawings on which a single feature has undergone multiple revisions. it is our practice to leave all revision letters on the drawing. for instance, a single dimension could have revision indicators a,b, and c all attached if it has been revised 3 times. should only the most recent revision level be shown? i tend to think so but we do not have a clear cut policy on this.
issue 2:
when removing a dimension or specification it is our "sop" to leave all revision indicators behind. i think we should remove them as this can leave a bunch of non-associated revision indicators behind = messy drawing. this can tie into issue 1 when multiple revisions are made to a single spec. what do other folks out there do?
thanks for your help!
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neither place i've worked has used revision indicators.  in my opinion they rapidly lead to a messy drawing.
at my first place the amendments (ecos) were very detailed so no information was lost or missing, it just didn't clutter the drawing.
at my current place the level of detail in ecos is minimal, the justification being that we keep the old revs of drawings.  i don't whole heartedly agree with this as sometimes it's more convenient to have a list of what's changed than have to compare the 2.
if i did do it i'd be inclined to do what you say.  i assume you'd leave the latest rev indicator at the removed dimension though to record removal?
kenat, probably the least qualified checker you'll ever meet...
issues 1&2:
from my perspective, the revision indictates are a communication to the vendor as to what areas of the drawing have changed from the previous revision.  i dislike them, but i understand they do sometimes have a place.
it is important to let the vendor know what's changing from the last time they saw a drawing.  if the part is made often, then only the last revision need indication.  however, if the part is made less often then the drawing is being revised, i can see how it might be important to leave all indicators.  
at any rate, i don't like using them at all, and we don't use them where i'm at.  if a vendor questions what has changed, we send them a vendor friendly ecopy of the eco, which is usually very descript about the changes occuring (id's before and afters, and zones affected).  this is better than any old messy tags on a drawing any day.
matt
cad engineer/ecn analyst
silicon valley, ca
i am used to leaving them on. every company i worked at left them on. but, the descriptions were minimal, then detailed on the eco.
understanding major and minor revs will lessen revision updates.
chris
solidworks 07 4.0/pdmworks 07
autocad 06
just to clarify, i was referring to revision indictors on the body of the drawing, not the detail of revisions in the revision block.   y14.35 allows for the removal of revisions from the revision block to make room for newer revisions.  if a revision is removed from the revision block, then its indentifiers on the drawing should also be removed.
matt
cad engineer/ecn analyst
silicon valley, ca