RE: [PROTEL EDA USERS]: Drill Drawing

[Abd ul-Rahman Lomax <marjan@vom.com>]

<x-flowed>
At 11:26 AM 9/27/00 -0500, Michael Biggs wrote:
>I just looked and I have always checked the box -"center plots on film"
>option when generating
>Gerbers. Why is this a problem? (using Protel98)

At the risk of beating a dead horse -- awful image, that --

If you are not going to check the drill files, and would never need to 
import the data back from gerber (hard to predict what will happen ten 
years from now) it won't create a problem for *you*, and it might or might 
not create a problem for whoever is going to drill the board. If they have 
a manual system for coordinating the drill information with the board 
image, there will be little or no additional problem, since they will 
already need to make a manual adjustment.

But if they will be using some kind of automated system, it might be a 
problem; manual intervention might be necessary to bring the holes into 
register with the copper image.

Further, a small registration error might be introduced in the process. 
Maybe. Depends.

If you don't center plots, and have the board set with absolute origin, the 
gerbers and drill file will share the same origin; otherwise the origin 
will need to be shifted for the drill.

However, to give the other side, if you are going to make checkplots from 
the gerbers, using a gerber editor, it might be a little more convenient 
that they will already be centered on a film size. Maybe.

But if you don't center them, you can set your film size to some large 
value and never have to think about it again. Centering is useless unless 
the film size is correct.... But if the file is not centered, "film size" 
has no effect on the plots except to give you an error if you plot outside 
the limits (Protel will abort the plot in this case).

marjan@vom.com
Abdulrahman Lomax
P.O. Box 690
El Verano, CA 95433



</x-flowed>