If I understand you correctly, you will need to edit the drill rack file 
(.drl) to list only the sizes you want to be drilled.  When you run the CAM 
processor, it will complain of a missing drill size, so you need to specify a 
drill tolerance so that it will find a close enough drill from what's 
available.  In the example you listed, a -1% should be enough.

When you get the gerber outputs, examine them carefully to ensure the affected 
holes/pads are acceptable in terms of size, annular ring, etc.  Also, the 
.dri file will report the substituted drills.

Yes, the central position will be the same, but the diameter will be 
different.

BTW, I would think that you would specify a tolerance *above* any missing 
drills, so the components will fit, unless you've verified otherwise.

Cheers,
-Neil.


On Wednesday 11 May 2005 05:06 pm, wayne scribbled:
> I have a circuit produced in eagle, with rather weird drill sizes... 0.60mm
> and .61mm for instance. Can I edit the drill rack file when producing
> gerbers to take these both to .60mm???. I'm assuming the central position
> of the drill will remain constant, but the size will change... am I right?
> Or should I do something else....
>
> Wayne


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