I am a creature of habit. Since tape-up days, I have always created a fab
dwg. It is a handy reference dwg for in-house use to double-check hole and
board size. Our fab dwgs include the dimensions and hole count table, the
layer stack and assignment, and any special notes that differ from our
standard specs. I thought all board houses would require a fab dwg for
reference to the data they have received. Or do a lot of them assume and go
with the data at hand and if made wrong, it is the clients fault! I work
very closely with my board houses, so that we both do not cause any

Bob Bauer 
Sr. Designer
Cardinal Scale Mfg. Co.
Webb City, Missouri

-----Original Message-----
From: Abd ul-Rahman Lomax [mailto:[EMAIL PROTECTED]]
Sent: Friday, February 22, 2002 10:54 AM
To: Protel EDA Forum

At 08:18 AM 2/22/2002 -0600, Bob Bauer wrote:
>I hear ya! The same problem with graphic symbols. Is there a cure?

The cure will leave you in better condition than before you got the disease.

The cure is to have Protel print the drill size on the drawing. If one 
stops and thinks about what a drill drawing is actually used for -- which 
is not much nowadays, unless one has used the layer for all fab notes, not 
a bad idea -- I think one will realize that the purpose is better served 
with the actual drill size being plotted rather than letters or symbols, 
both of which slow down the reader because they must reference a table.

Yes, the drill symbols can interfere with each other, so one must, to make 
the drawing intelligible, make the symbols small enough that a 1:1 plot 
would not be readable. But there is no need to *ever* make a 1:1 plot of a 
drill drawing. The fabricators will use the drill file, not the drill 
drawing (except for outline and reference locations), which has become, 
almost completely, only a tool that we can use to visually check what sizes 
have been assigned.

Protel could help us by making drill size display a view option, along with 
pad numbers and nets.

(By the way, drill size accuracy is pretty gross; it is typical that the 
fabricator has at least 2 mils of deviation from nominal for acceptance. So 
rounding of drill sizes would be preferred. The fabricator is going to do 
it anyway, matching the drill sizes in stock. A more sophisticated tool 
would choose drill sizes by default, taking them back into the PCB 
database, I won't go into details at this time.)

Abdulrahman Lomax
Easthampton, Massachusetts USA

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