Ross,

One thing I have learned over the years is keep it simple.  Put what you need to put on the print and always try and be as specific as possible. I think you will find that most board shops have a very good understanding GDT.  Another thing you should consider is your receiving inspection area.  Don't forget, that whatever you put on your drawing, your own personnel will have to work with as well.  Just my thoughts...

Ed Cosper
Director Quality Assurance and Engineering
Graphic Electronics Inc.
Tulsa OK

----------
From:  Ross A. Eskite[SMTP:[log in to unmask]]
Sent:  Monday, April 13, 1998 3:36 PM
To:  [log in to unmask]
Subject:  [TN] Geometric dimensioning & tolerancing

Greetings-

We are currently in the midst of a lively discussion
in our CAD department over the pros and cons of
geometric dimensioning and tolerancing (GDT) when
used on PWB fabrication drawings.  From what I've seen:

Pros:
  More accurate (potentially)
  Provides maximum producibility in achievement of
    desired fit (when competently applied)
  "Encouraged" by IPC

Cons:
  Poorly understood by many draftsmen
  Poorly understood by some board shops (this bothers me)
  Takes longer to produce a drawing
  Many consider it "overkill"

I'd like some feedback from other designers, board shops,
ME's, etc., on this issue.  Has anyone had any compellingly
positive or negative experiences with GDT?  Would you write
it into *your* PWB CAD process?

TIA,
--
Ross Eskite
"Though I fervently recite the Mass in perfect Latin to the cannibals,
somehow I always end up in the big black pot with the carrots" - me

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