Hello Ron,

There is certainly some merit in your standard symbols, for the reasons you
state.
However, as you are finding, it's hard to have enough clearly different
symbols to accommodate all possible drill sizes.
We do not use standard drill symbols and the software I use (Protel)
doesn't support this.
We do of course minimise the number of different drill sizes in a design,
and our software automatically generates a legend of symbols for our master
drawings. Our engineers are happy with this, and I've had no problems with
our manufacturers. Rarely do I see the number of different drill sizes in a
given design go above 10, so having to cross check to the legend is no
great hassle. In fact, it makes you look closer.

regards,

Phil.

At 14:13 7/03/00 -0500, you wrote:
>      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


Phil Dutton C.I.D.
Senior CAD Technician
IPC Certified Interconnect Designer

Vision Abell Pty Ltd
Second Avenue, Technology Park,
Mawson Lakes.  SOUTH AUSTRALIA  5095
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