This will probably get me into trouble, but as a fabricator I have to
throw my two cents in.

I beleive the objection they have is 'to be within .003 of pad
center' - not to  the intended true position of the hole. Modern drill
 equiptment will generally give you less than .001" drill wander.
Artwork and layer registration issues will be greater, hence the
 huge layer to layer registration tolerances in 55110 and other specs.
These specs generally allow the pad to be off-location,  but not the hole.

What you need is registration to the true position. It's a fine
distinction, but sometimes us fab guys have to really analyze what
the designers are saying and what they really mean.




 You wrote;

>      Hi All,
>
>      Here's the issue:
>
>      We specify in our fab spec that all holes are to be within .003" of
>      their corresponding pad center (true position of .006"). We are being
>      told by our fab house that this tolerance is unreasonably tight.
>
>      Any comments???
>
>      Thanks,
>      Rick

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