Re: [PROTEL EDA USERS]: Drill Drawing

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

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At 11:43 AM 9/27/00 -0400, HxEngr@aol.com wrote:

>Never, ever, turn on the "center plots on film" option when generating
>Gerbers.

Since this was explained in an earlier post in this thread, perhaps it is 
appropriate to detail what this option does.

It gives an offset to the gerber data such that the plot will be centered 
on the film. Thus such a plot will not match the drill file, which has no 
offset.

I think that "center plots" is turned on by default. Whoever set that was 
thinking of making matters more convenient for the photoplotting people; 
but I would assume that any photoplotter worth its kilobucks would already 
center plots automatically, or at least move them out to provide a margin 
if necessary; or this could be done by the CAM software when the gerbers 
are reviewed by the fabricator before the plots are made. Since it is not 
at all uncommon that the fabricator will want to tweak the files in some 
way, I'd be surprised to see a fabricator try to plot gerber without 
previewing it.

As a design set, however, the drill and films should have the same origin, 
which *requires*, with Protel, that absolute origin be set in PCB and that 
centering be turned off in the gerber setup. It's one of the options on the 
last tab of the properties dialog for a CAM Manager gerber output file.


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



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