"Wolfe, Robert" wrote:
> Ron,
> It depends on whether in your specific process it would make sense. In my
> opinion vendors would see so many variations
> from different companies that I do not see how it would help them any to
> make it standard, unless it where an industry standard,
> and I don't think we will see that happen. So using your particular software
> do it in the most automated fashion would be my vote and I would think it
> would be the most accurate.
> Executone Inter-Tel Business Information Systems, Inc.
> Robert M. Wolfe C.I.D.
> Lead PCB Designer
> 478 Wheelers Farms Road
> Milford, CT 06460
> Phone: 203-882-6405
> Fax: 203-882-2727
> Email: [log in to unmask]
>
> > -----Original Message-----
> > From: Ron James [SMTP:[log in to unmask]]
> > Sent: Tuesday, March 07, 2000 2:13 PM
> > To: [log in to unmask]
> > Subject: [DC] Drill symbol standardization
> >
> > I would like to take an informal poll of other designers on the lists
> > to see how many companies use standardized drill symbols on
> > fabrication drawings. (i.e. always use the same symbol for .021
> > holes, etc, on all fab drawings for all designs.)
> >
> > We changed from PCAD to Orcad a couple of years ago. In PCAD we
> > built
> > the padstacks to include the symbol, so by default used a standard
> > symbol for each size. Orcad handles drill symbols by automatically
> > assigning them and creating a chart in the database (a very nice
> > feature from my point of view.) The symbol/size association will be
> > different from one design to another. Also, Orcad is limited to 46
> > different symbols, and we are already pushing that number of drill
> > sizes for our entire library. This means that if we want to use
> > standard symbols across all designs, we will have to bypass Orcad's
> > automatic symbol assignment and come up with a very manual process.
> >
> > This question is being prompted by engineers who really liked the
> > standardized symbols, and feel that their ability to check drawings
> > is
> > made significantly easier by that system. They have been burned in
> > the past by hole size issues and feel that such errors will be more
> > difficult to catch if they can no longer compare drawings at a glance
> > (new vs old revisions, or two unrelated designs that use the same
> > parts, etc.)
> >
> > To sum up my questions:
> > 1) Does your company use standard hole size symbols across all
> > designs?
> > 2) If so, does your software accommodate this, or is it a manual
> > process for you?
> > 3) If so, do your end users (design, manufacturing or process
> > engineers) find this to be valuable?
> >
> >
> > Thanks for any and all assistance. Please pardon the duplication
> > between lists.
> >
> > Ron James, CID
> > UT Electronic Controls
I agree with Robert Wolfe. We fill our drill table and select our drill
symbols
automatically with one button and even include special tolerances. We have
25 drill symbols that are automatically read into the database and the software
automatically selects which one to put on which drill size. In this day of
surface
mount parts, we hardly ever have more than 15 drills. We don't consolidate
drills either. Let the board vendor do that if he wants. Our librarians try
to
use standard drill sizes but if it is necessary to have an odd size they will
use it.
The only time engineers even look at drill sizes is at the beginning of the
process
when the board profile is checked by the mechanical engineer against his
model.
My vote is for automating the process as much as possible so that there is less
chance of human error. If an error is found, it can be fixed once so it doen't
happen again. To automate the process easily though, some of the old thinking
about drill size consolidation and assigning drill symbols to certain drills
could
make it harder to do. We dropped those requirements to get the automation
done quickly and with less complexity.
John Bradley
Alcatel USA
Plano, TX
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